RESUMEN

A QTL for host response to porcine reproductive and respiratory syndrome (PRRS) was identified in a previous study. The SNP WUR10000125 (WUR) is used as a tag SNP for this QTL. The favorable (B) allele at this SNP is in low frequency in commercial populations, possibly because this allele is unfavorably associated with an important trait under nonchallenging conditions and, therefore, may have been selected against. Therefore, objectives of this study were to estimate the effect of WUR on traits under selection in commercial lines under nonchallenging conditions and to estimate the effect of WUR genotype of parents on performance of crossbred progeny in a commercial-like environment. Data were collected on 4 purebred lines: a Landrace dam line (D1), a Large White dam line (D2), a synthetic sire line (S1), and a Pietrain sire line (S2). Traits analyzed included total number born, number stillborn, farrowing survival, lactation survival, litter mortality, daily feed intake (DFI), backfat, average test daily gain (TGR), average lifetime daily gain (LGR), and Topigs Norsvin selection index (TSI) value, indicative of overall economic value. Deregressed EBV were calculated for each trait (except TSI) and analyzed within line. In the S1 line, AB and BB pigs had significantly lower TGR ( = 0.002) and LGR ( = 0.001) than AA pigs but also lower DFI ( = 0.004). Conversely, AB and BB pigs had significantly higher DFI ( < 0.001) and AB pigs had significantly higher TGR ( = 0.03) than AA pigs in the S2 line. The effect of WUR on TSI was not significant for any line ( ≥ 0.15). Analyses of phenotypic records collected on crossbred progeny of S1 sires and D1 × D2 F females showed no significant effect of parent WUR genotype on DFI, backfat, TGR, or LGR ( ≥ 0.07). In conclusion, the effect of WUR was nonsignificant for most traits but the magnitude and direction of the effect differed by trait and by line. The favorable allele for host response to PRRS was associated with greater DFI and a tendency for greater TGR in the S2 line, but the opposite direction of effect was detected for the S1 line. Regardless of the effect on individual traits, no significant effect of WUR on TSI was detected for any line. Therefore, selecting for the B allele is expected to result in progeny with increased resistance to PRRS without compromising overall economic value under normal, nonchallenging conditions.

Asunto(s)

Síndrome Respiratorio y de la Reproducción Porcina/genética , Virus del Síndrome Respiratorio y Reproductivo Porcino/inmunología , Alelos , Animales , Ingestión de Alimentos , Femenino , Genotipo , Lactancia , Masculino , Paridad , Fenotipo , Síndrome Respiratorio y de la Reproducción Porcina/inmunología , Embarazo , Mortinato , Porcinos

RESUMEN

Seasonal infertility is often observed as anestrus and a lower conception rate resulting in a reduced farrowing rate (FR) during late summer and early autumn. This is often regarded as an effect of heat stress; however, we observed a reduction in the FR of sows even after correcting for ambient temperature in our data. Therefore, we added change in photoperiod in the analysis of FR considering its effect on sow fertility. Change in photoperiod was modeled using the cosine of the day of first insemination within a year. On an average, the FR decreased by 2% during early autumn with decreasing daily photoperiod compared with early summer with almost no change in daily photoperiod. It declined 0.2% per degree Celsius of ambient temperature above 19.2°C. This result is a step forward in disentangling the 2 environmental components responsible for seasonal infertility. Our next aim was to estimate the magnitude of genetic variation in FR in response to change in photoperiod and ambient temperature to explore opportunities for selecting pigs to have a constant FR throughout the year. We used reaction norm models to estimate additive genetic variation in response to change in photoperiod and ambient temperature. The results revealed a larger genetic variation at stressful environments when daily photoperiod decreased and ambient temperatures increased above 19.2°C compared with neutral environments. Genetic correlations between stressful environments and nonstressful environments ranged from 0.90 (±0.03) to 0.46 (±0.13) depending on the severity of the stress, indicating changes in expression of FR depending on the environment. The genetic correlation between responses of pigs to changes in photoperiod and to those in ambient temperature were positive, indicating that pigs tolerant to decreasing daily photoperiod are also tolerant to high ambient temperatures. Therefore, selection for tolerance to decreasing daily photoperiod should also increase tolerance to high ambient temperatures or vice versa.

Asunto(s)

Fertilidad/fisiología , Variación Genética , Calor , Fotoperiodo , Estrés Fisiológico , Porcinos/fisiología , Animales , Femenino , Inseminación , Embarazo

RESUMEN

Robustness is an important issue in the pig production industry. Since pigs from international breeding organizations have to withstand a variety of environmental challenges, selection of pigs with the inherent ability to sustain their productivity in diverse environments may be an economically feasible approach in the livestock industry. The objective of this study was to estimate genetic parameters and breeding values across different levels of environmental challenge load. The challenge load (CL) was estimated as the reduction in reproductive performance during different weeks of a year using 925,711 farrowing records from farms distributed worldwide. A wide range of levels of challenge, from favorable to unfavorable environments, was observed among farms with high CL values being associated with confirmed situations of unfavorable environment. Genetic parameters and breeding values were estimated in high- and low-challenge environments using a bivariate analysis, as well as across increasing levels of challenge with a random regression model using Legendre polynomials. Although heritability estimates of number of pigs born alive were slightly higher in environments with extreme CL than in those with intermediate levels of CL, the heritabilities of number of piglet losses increased progressively as CL increased. Genetic correlations among environments with different levels of CL suggest that selection in environments with extremes of low or high CL would result in low response to selection. Therefore, selection programs of breeding organizations that are commonly conducted under favorable environments could have low response to selection in commercial farms that have unfavorable environmental conditions. Sows that had experienced high levels of challenge at least once during their productive life were ranked according to their EBV. The selection of pigs using EBV ignoring environmental challenges or on the basis of records from only favorable environments resulted in a sharp decline in productivity as the level of challenge increased. In contrast, selection using the random regression approach resulted in limited change in productivity with increasing levels of challenge. Hence, we demonstrate that the use of a quantitative measure of environmental CL and a random regression approach can be comprehensively combined for genetic selection of pigs with enhanced ability to maintain high productivity in harsh environments.

Asunto(s)

Cruzamiento/métodos , Ambiente , Selección Genética , Sus scrofa/genética , Sus scrofa/fisiología , Animales , Cruzamiento/normas , Femenino , Análisis de Regresión , Reproducción/fisiología , Porcinos

RESUMEN

A method was developed and tested to estimate challenge load due to disease outbreaks and other challenges in sows using reproduction records. The method was based on reproduction records from a farm with known disease outbreaks. It was assumed that the reduction in weekly reproductive output within a farm is proportional to the magnitude of the challenge. As the challenge increases beyond certain threshold, it is manifested as an outbreak. The reproduction records were divided into 3 datasets. The first dataset called the Training dataset consisted of 57,135 reproduction records from 10,901 sows from 1 farm in Canada with several outbreaks of porcine reproductive and respiratory syndrome (PRRS). The known disease status of sows was regressed on the traits number born alive, number of losses as a combination of still birth and mummified piglets, and number of weaned piglets. The regression coefficients from this analysis were then used as weighting factors for derivation of an index measure called challenge load indicator. These weighting factors were derived with i) a two-step approach using residuals or year-week solutions estimated from a previous step, and ii) a single-step approach using the trait values directly. Two types of models were used for each approach: a logistic regression model and a general additive model. The estimates of challenge load indicator were then compared based on their ability to detect PRRS outbreaks in a Test dataset consisting of records from 65,826 sows from 15 farms in the Netherlands. These farms differed from the Canadian farm with respect to PRRS virus strains, severity and frequency of outbreaks. The single-step approach using a general additive model was best and detected 14 out of the 15 outbreaks. This approach was then further validated using the third dataset consisting of reproduction records of 831,855 sows in 431 farms located in different countries in Europe and America. A total of 41 out of 48 outbreaks detected using data analysis were confirmed based on diagnostic information received from the farms. Among these, 30 outbreaks were due to PRRS while 11 were due to other diseases and challenging conditions. The results suggest that proposed method could be useful for estimation of challenge load and detection of challenge phases such as disease outbreaks.

Asunto(s)

Brotes de Enfermedades/veterinaria , Síndrome Respiratorio y de la Reproducción Porcina/epidemiología , Virus del Síndrome Respiratorio y Reproductivo Porcino , Reproducción/fisiología , Enfermedades de los Porcinos/epidemiología , Enfermedades de los Porcinos/virología , Animales , Peso Corporal/fisiología , Canadá/epidemiología , Femenino , Modelos Logísticos , Países Bajos/epidemiología , Porcinos , Carga Viral/veterinaria

RESUMEN

In the era of genome-wide selection (GWS), genotype-by-environment (G×E) interactions can be studied using genomic information, thus enabling the estimation of SNP marker effects and the prediction of genomic estimated breeding values (GEBV) for young candidates for selection in different environments. Although G×E studies in pigs are scarce, the use of artificial insemination has enabled the distribution of genetic material from sires across multiple environments. Given the relevance of reproductive traits, such as the total number born (TNB) and the variation in environmental conditions encountered by commercial dams, understanding G×E interactions can be essential for choosing the best sires for different environments. The present work proposes a two-step reaction norm approach for G×E analysis using genomic information. The first step provided estimates of environmental effects (herd-year-season, HYS), and the second step provided estimates of the intercept and slope for the TNB across different HYS levels, obtained from the first step, using a random regression model. In both steps, pedigree ( A: ) and genomic ( G: ) relationship matrices were considered. The genetic parameters (variance components, h(2) and genetic correlations) were very similar when estimated using the A: and G: relationship matrices. The reaction norm graphs showed considerable differences in environmental sensitivity between sires, indicating a reranking of sires in terms of genetic merit across the HYS levels. Based on the G: matrix analysis, SNP by environment interactions were observed. For some SNP, the effects increased at increasing HYS levels, while for others, the effects decreased at increasing HYS levels or showed no changes between HYS levels. Cross-validation analysis demonstrated better performance of the genomic approach with respect to traditional pedigrees for both the G×E and standard models. The genomic reaction norm model resulted in an accuracy of GEBV for "juvenile" boars varying from 0.14 to 0.44 across different HYS levels, while the accuracy of the standard genomic prediction model, without reaction norms, varied from 0.09 to 0.28. These results show that it is important and feasible to consider G×E interactions in evaluations of sires using genomic prediction models and that genomic information can increase the accuracy of selection across environments.

Asunto(s)

Cruzamiento , Genómica , Porcinos/genética , Animales , Ambiente , Femenino , Genoma , Genotipo , Masculino , Modelos Genéticos , Linaje , Fenotipo , Porcinos/fisiología

RESUMEN

Genetic selection for increased litter size of sows increases the risk of a large negative energy balance during lactation. Furthermore, the feed intake capacity of the lactating sows might be reduced due to the simultaneous selection for greater feed efficiency during the growth phase when sows were actually reared as finishers but later on selected for breeding. There is a need to improve lactation performance of sows and continue selection for feed efficiency of grower-finishers in commercial breeding. Therefore, this study was conducted to estimate genetic correlations between growing-finishing traits and lactation performance traits. An additional objective was to study the impact of including additive social effects in the animal model on genetic correlation estimates. Analyses were performed on a population of 1,149 commercial crossbred sows with repeated observations on lactation performance traits and their 7,723 grower-finisher offspring. The genetic correlation between daily BW gain of grower-finishers and starting BW of lactating sows was positive (rg = 0.24; P < 0.05). The correlation between off-test backfat of grower-finishers and fat mass of lactating sows was also positive (rg = 0.53; P < 0.05). The genetic regulation of feed intake from the beginning of lactation seems to differ from the genetic regulation of feed intake during the growing-finishing period, as the correlation between these 2 traits was low (rg = +0.23; P < 0.05). Feed efficiency during growing-finishing and lactation phases showed similar tendencies as the genetic correlation between residual feed intake of the grower-finisher and lactation efficiency of sows was -0.51 (P < 0.05). Taking heritable social effects into account for daily BW gain and feed intake did not affect the genetic correlation estimates, either within growing-finishing traits or between growing-finishing traits and lactation performance traits. It was concluded that in the absence of antagonistic genetic correlations, selection for growing-finishing traits in dam lines could be combined with selection for lactation performance traits.

Asunto(s)

Lactancia/genética , Porcinos/genética , Porcinos/fisiología , Aumento de Peso/genética , Animales , Metabolismo Energético/genética , Metabolismo Energético/fisiología , Femenino , Estudios de Asociación Genética , Lactancia/fisiología , Porcinos/crecimiento & desarrollo , Aumento de Peso/fisiología

RESUMEN

A reduction in boar taint, an unpleasant odor arising in pork from some intact males, is desirable if routine castration of piglets needs to be stopped. Commercial slaughter pigs are typically crosses between sire lines mainly selected for finishing traits and dam lines mainly selected for reproduction traits. Previous studies suggest the possibility of reducing boar taint in sire lines due to favorable genetic correlations between boar taint and finishing traits. However, there are indications of unfavorable genetic associations between boar taint and female reproduction traits, but a lack of genetic correlation estimates remain a major roadblock in reducing boar taint in dam lines. This study was conducted to estimate genetic correlations between boar taint traits and female reproduction traits, investigate differences in these genetic relationships among sire and dam lines, and evaluate possible consequences of selection against boar taint in dam lines. The data consisted of 32,549 reproduction records from a Landrace dam line, 23,874 records from a Yorkshire dam line, and 3,745 records from a Pietrain sire line. Androstenone, skatole, and indole were measured on 1,896 carcasses, and human nose scores were recorded on 7,742 carcass samples. In general, the level of boar taint was significantly greater (P < 0.05) in the two dam lines than in the sire line. A majority of genetic correlations of boar taint compounds with reproduction traits were either low or nonsignificant, except for those of skatole and indole, with age at first insemination in dam lines that were -0.32 and -0.46, respectively. Genetic correlations also differed (P < 0.05) between sire and dam lines. The consequences of selection against boar taint in dam lines were evaluated, using selection indexes based on reproduction traits only, boar taint traits only, and both boar taint and reproduction traits. Selection on an index of only reproduction traits increased the number of carcasses with boar taint from 4 to 7.3% in 5 generations. Selection on a combined index reduced carcasses with boar taint from 4 to <0.1% in 19 generations at the cost of a 10% less economic gain in reproduction traits. In markets for intact males, overall economic gain is 78% greater than with selection for reproduction only. Breeding programs for boar taint in commercial production should include boar taint in breeding goals of dam lines as the levels of boar taint and the risk of a further increase are greater.

Asunto(s)

Androstenos/metabolismo , Indoles/metabolismo , Carne/análisis , Selección Genética , Sus scrofa/fisiología , Animales , Cruzamiento , Cromatografía Líquida de Alta Presión/veterinaria , Cromatografía Liquida/veterinaria , Femenino , Masculino , Espectrometría de Masas/veterinaria , Odorantes/análisis , Carácter Cuantitativo Heredable , Escatol/metabolismo , Sus scrofa/genética

RESUMEN

Heat stress is known to adversely affect reproductive performance of sows. However, it is important to know on which days or periods during the reproduction cycle heat stress has the greatest effects for designing appropriate genetic or management strategies. Therefore, this study was conducted to identify days and periods that have greatest effects on farrowing rate and total born of sows using 5 different measures of heat stress. The data consisted of 22,750 records on 5024 Dutch Yorkshire dam line sows from 16 farms in Spain and Portugal. Heat stress on a given day was measured in terms of maximum temperature, diurnal temperature range and heat load. The heat load was estimated using 3 definitions considering different upper critical temperatures. Identification of days during the reproduction cycle that had maximum effect was based on the Pearson correlation between the heat stress variable and the reproduction trait, estimated for each day during the reproduction cycle. Polynomial functions were fitted to describe the trends of these correlations and the days with greatest negative correlation were considered as days with maximum effect. Correlations were greatest for maximum temperature, followed by those for heat load and diurnal temperature range. Correlations for both farrowing rate and total born were stronger in gilts than in sows. This implies that heat stress has a stronger effect on reproductive performance of gilts than of sows. Heat stress during the third week (21 to 14 d) before first insemination had largest effect on farrowing rate. Heat stress during the period between 7 d before successful insemination until 12 d after that had largest effect on total born. Correlations between temperatures on consecutive days during these periods were extremely high ( > 0.9). Therefore, for farrowing rate the maximum temperature on 21 d before first insemination and for total born the maximum temperature at day of successful insemination can be used as predictive measures of heat stress in commercial sow farms. Additionally, differences between daughter groups of sires were identified in response to high temperatures. This might indicate possibilities for genetic selection on heat tolerance.

Asunto(s)

Respuesta al Choque Térmico , Reproducción , Sus scrofa/fisiología , Animales , Femenino , Calor , Inseminación , Tamaño de la Camada , Paridad , Portugal , Embarazo , España , Factores de Tiempo

RESUMEN

Pig breeders in the past have adopted their breeding goals according to the needs of the producers, processors and consumers and have made remarkable genetic improvements in the traits of interest. However, it is becoming more and more challenging to meet the market needs and expectations of consumers and in general of the citizens. In view of the current and future trends, the breeding goals have to include several additional traits and new phenotypes. These phenotypes include (a) vitality from birth to slaughter, (b) uniformity at different levels of production, (c) robustness, (d) welfare and health and (e) phenotypes to reduce carbon footprint. Advancements in management, genomics, statistical models and other technologies provide opportunities for recording these phenotypes. These new developments also provide opportunities for making effective use of the new phenotypes for faster genetic improvement to meet the newly adapted breeding goals.

Asunto(s)

Cruzamiento/normas , Porcinos/genética , Crianza de Animales Domésticos , Animales , Animales Recién Nacidos/genética , Animales Recién Nacidos/crecimiento & desarrollo , Cruzamiento/métodos , Huella de Carbono , Resistencia a la Enfermedad/genética , Carne/normas , Fenotipo , Porcinos/anatomía & histología , Porcinos/crecimiento & desarrollo , Temperatura

RESUMEN

A system for sensory evaluation of boar taint was used to evaluate boar taint in fat samples from 6574 entire males. The term "human nose scoring" has been used to describe this system. The samples from each boar were heated with a hot iron and three panelists assigned scores of 0 to 4. The reproducibility of HNS ranged from 0.19 to 0.32 reflecting natural variation in the ability of human beings to detect different odors. The correlations of HNS with androstenone ranged from 0.22 to 0.52, while those with skatole ranged from 0.31 to 0.89, suggesting that skatole is a better predictor of boar taint. Considering (1) the relationship of HNS with the boar taint compounds, (2) the ability of HNS to capture variation not accounted for by the boar taint compounds, (3) low estimation costs and (4) low time requirements, HNS can be used in large scale evaluations of boar taint.

Asunto(s)

Androstenos/análisis , Carne/análisis , Nariz , Odorantes/análisis , Escatol/análisis , Olfato , Animales , Calor , Humanos , Masculino , Reproducibilidad de los Resultados , Porcinos

RESUMEN

The purpose of this study was to evaluate measures of boar (Sus scrofa) taint as potential selection criteria to reduce boar taint so that castration of piglets will become unnecessary. Therefore, genetic parameters of boar taint measures and their genetic correlations with finishing traits were estimated. In particular, the usefulness of a human panel assessing boar taint (human nose score) was compared with chemical assessment of boar taint compounds, androstenone, skatole, and indole. Heritability estimates for androstenone, skatole, and indole were 0.54, 0.41, and 0.33, respectively. The heritability for the human nose score using multiple panelists was 0.12, and ranged from 0.12 to 0.19 for individual panelists. Genetic correlations between scores of panelists were generally high up to unity. The genetic correlations between human nose scores and the boar taint compounds ranged from 0.64 to 0.999. The boar taint compounds and human nose scores had low or favorable genetic correlations with finishing traits. Selection index estimates indicated that the effectiveness of a breeding program based on human nose scores can be comparable to a breeding program based on the boar taint compounds themselves. Human nose scores can thus be used as a cheap and fast alternative for the costly determination of boar taint compounds, needed in breeding pigs without boar taint.

Asunto(s)

Androsterona/química , Indoles/química , Carne/análisis , Escatol/química , Animales , Humanos , Masculino , Odorantes , Linaje , Selección Genética , Porcinos/genética , Porcinos/metabolismo

RESUMEN

Today, different analytical methods are used by different laboratories to quantify androstenone in fat tissue. This study shows the comparison of methods used routinely in different laboratories for androstenone quantification: Time-resolved fluoroimmunoassay in Norwegian School of Veterinary Science (NSVS; Norway), gas chromatography coupled to mass spectrometry in Co-operative Central Laboratory (CCL; The Netherlands) and in Institut de Recerca i Tecnologia Agroalimentàries (IRTA; Spain), and high-pressure liquid chromatography in Agroscope Liebefeld-Posieux Research Station (ALP; Switzerland). In a first trial, a set of adipose tissue (AT) samples from 53 entire males was sent to CCL, IRTA and NSVS for determination of androstenone concentration. The average androstenone concentration (s.d.) was 2.47 (2.10) µg/g at NSVS, 1.31 (0.98) µg/g at CCL and 0.62 (0.52) µg/g at IRTA. Despite the large differences in absolute values, inter-laboratory correlations were high, ranging from 0.82 to 0.92. A closer look showed differences in the preparation step. Indeed, different matrices were used for the analysis: pure fat at NSVS, melted fat at CCL and AT at IRTA. A second trial was organised in order to circumvent the differences in sample preparation. Back fat samples from 10 entire males were lyophilised at the ALP labortary in Switzerland and were sent to the other laboratories for androstenone concentration measurement. The average concentration (s.d.) of androstenone in the freeze-dried AT samples was 0.87 (0.52), 1.03 (0.55), 0.84 (0.46) and 0.99 (0.67) µg/g at NSVS, CCL, IRTA and ALP, respectively, and the pairwise correlations between laboratories ranged from 0.92 to 0.97. Thus, this study shows the influence of the different sample preparation protocols, leading to major differences in the results, although still allowing high inter-laboratory correlations. The results further highlight the need for method standardisation and inter-laboratory ring tests for the determination of androstenone. This standardisation is especially relevant when deriving thresholds of consumer acceptance, whereas the ranking of animals for breeding purposes will be less affected due to the high correlations between methods.

RESUMEN

Endosulfan, a widely used organochlorine pesticide, is readily bio-accumulative in fishes and can be indirectly harmful to human populations. Limited efforts have been made to study long-term genotoxic effects of endosulfan in different tissues of fish using gentoxicity biomarkers. Therefore, the current investigation was undertaken to detect single-cell DNA strand breaks induced by endosulfan in the fresh water teleost fish Mystus vittatus using the comet assay. The LC(50) value of technical grade endosulfan was first determined for the fish species in a semistatic system, and on the basis of the LC(50) value, the sublethal and nonlethal concentrations were determined. The DNA damage was measured in gill, kidney, and erythrocytes as the percentage of DNA in comet tails of fish specimens exposed to the sublethal and nonlethal concentrations of endosulfan. In general, significant effects (p < 0.01) from both concentration and time of exposure were observed in exposed fishes. It was found that all the tissues at all concentrations exhibited the highest DNA damage on day 1, after which there was a nonlinear decline in the percentage of tail DNA. The comparison of DNA damage among the tissues at different concentrations could not show the sensitivity of particular tissue to endosulfan. The current study explored the utility of the comet assay for in vivo laboratory studies using fish species to screen the genotoxic potential of chemical agents.

Asunto(s)

Endosulfano/toxicidad , Peces/genética , Contaminantes Químicos del Agua/toxicidad , Animales , Ensayo Cometa , Eritrocitos/efectos de los fármacos , Agua Dulce , Branquias/efectos de los fármacos , Riñón/efectos de los fármacos

RESUMEN

A simple, rapid and accurate method for the determination of iodate in iodized common salts has been developed. The quantitative determination of iodate was accomplished by anion exchange chromatography with conductimetric detection. The method requires a sample pretreatment for the removal of large excess of chloride from the sample matrix. Onguard silver cartridges were found most suitable for this purpose. The sulphate content in the salt was simultaneously determined. The lower limits for the determination of iodate and sulphate in solution are 0.5 and 0.05 mug ml(-1), respectively. Quantitative recovery of the anions in synthetic samples has been obtained and the interferences from different cations and anions have been studied. The method has been successfully applied to the determination of iodate and sulphate in the commercially available salts. The concentrations of iodate measured by this method are in good agreement with those claimed by the manufacturer.

RESUMEN

The genetic variability of various local chicken populations derived from Bolivia, India, Nigeria and Tanzania was evaluated with 22 microsatellites. Between two and 11 alleles per locus were detected. All populations showed high levels of heterozygosity with the lowest value of 45% for the population named Aseel from India and the highest value of 67% for Arusha from Tanzania. A dendrogram was constructed based on CHORD distance by upgMa analysis. Within this tree the populations were assorted according to their geographical origin. Bootstrapping values within the dendrogram were between 37 and 99%. The contribution of the determination of genetic variability with genetic markers to the decision on conservation and/or further use of the populations in crossbreeding programs designed to create genetic stocks with improved adaptability and productivity in tropical countries is discussed.

Asunto(s)

Pollos/genética , Variación Genética , África , Alelos , Crianza de Animales Domésticos , Animales , Asia , Genética de Población , Heterocigoto , Repeticiones de Microsatélite , América del Sur , Clima Tropical

RESUMEN

We have cloned and sequenced a 906bp EcoRI repeat DNA fraction from Rhinoceros unicornis genome. The contig pSS(R)2 is AT rich with 340 A (37.53%), 187 C (20.64%), 173 G (19.09%) and 206 T (22.74%). The sequence contains MALT box, NF-E1, Poly-A signal, lariat consensus sequences, TATA box, translational initiation sequences and several stop codons. Translation of the contig showed seven different types of protein motifs, among which, EGF-like domain cysteine pattern signatures and Bowman-Birk serine protease inhibitor family signatures were prominent. The presence of eukaryotic transcriptional elements, protein signatures and analysis of subset sequences in the 5' region from 1 to 165nt indicating coding potential (test code value=0.97) suggest possible regulatory and/or functional role(s) of these sequences in the rhino genome. Translation of the complementary strand from 906 to 706nt and 190 to 2nt showed proteins of more than 7kDa rich in non-polar residues. This suggests that pSS(R)2 is either a part of, or adjacent to, a functional gene. The contig contains mostly non-consecutive simple repeat units from 2 to 17nt with varying frequencies, of which four base motifs were found to be predominant. Zoo-blot hybridization revealed that pSS(R)2 sequences are unique to R. unicornis genome because they do not cross-hybridize, even with the genomic DNA of South African black rhino Diceros bicornis. Southern blot analysis of R. unicornis genomic DNA with pSS(R)2 and other synthetic oligo probes revealed a high level of genetic homogeneity, which was also substantiated by microsatellite associated sequence amplification (MASA). Owing to its uniqueness, the pSS(R)2 probe has a potential application in the area of conservation biology for unequivocal identification of horn or other body tissues of R. unicornis. The evolutionary aspect of this repeat fraction in the context of comparative genome analysis is discussed.

Asunto(s)

Perisodáctilos/genética , Secuencias Repetitivas de Ácidos Nucleicos/genética , Animales , Southern Blotting , Búfalos , Camelus , Bagres , Bovinos , Columbidae , ADN/química , ADN/genética , Sondas de ADN , Femenino , Cabras , Gryllidae , Humanos , Masculino , Ratones , Repeticiones de Microsatélite/genética , Datos de Secuencia Molecular , Sondas de Oligonucleótidos/síntesis química , Sistemas de Lectura Abierta , Filogenia , Reacción en Cadena de la Polimerasa , Polimorfismo Genético , Polimorfismo de Longitud del Fragmento de Restricción , Conejos , Ratas , Análisis de Secuencia de ADN , Especificidad de la Especie , Estadística como Asunto , Porcinos

RESUMEN

A flow injection method for the determination of boron using a conductivity detector has been described. Boric acid injected into the flow system reacts with mannitol (0.3 M) in the mobile phase and an equivalent amount of H(+) is liberated in the stream. The increase in the conductance of the mobile phase due to the liberated H(+) has been equated to the boron concentration in the sample. A linear calibration for light- and heavy-water samples containing 0-20 µg/mL boron was obtained. Boron concentrations in the samples of light and heavy water and lithium pentaborate solution have been measured. The interferences due to various ions such as Na(+), Li(+), Cu(2+), Ni(2+), Co(2+), Fe(3+), Al(3+), SO(4)(2-), NO(3)(-), F(-), and Cl(-) could be eliminated by adopting a two-step sample pretreatment procedure. In the first step, all the anions were converted to Cl(-) by treating the sample solution with a strong anion-exchange resin. In the second step, the solution obtained from the first step was passed through a silver-guard cartridge to remove interfering cations and Cl(-). The relative standard deviation was ±0.25% for the determination of 1 µg of boron in light water, and the limit of detection was 0.01 µg present in an injection volume of 100 µL. The corresponding values for heavy water were ±0.38% and 0.1 µg, respectively.

RESUMEN

UV-vis spectrophotometric method for the analysis of cyclohexylamine (CHA) in aqueous medium in the range of 0.3-20 ppm was developed by coupling CHA with sodium 1,2-naphthaquinone-4-sulphonate (NQS). At 470 nm a calibration slope of 0.028 OD ppm(-1) was observed. Minimum detection limit was 0.3 ppm with standard deviation of 0.1 ppm. Reagent concentration and solution pH for the analysis are optimised by studying its effect on absorbance at 470 nm. The method was applied to analyse CHA for evaluating the performance of ion exchange resin used in condensate purification plant (CPP) of power station where, CHA is used as all volatile treatment (AVT) reagent to inhibit steam generator (SG) corrosion. Structure of the adduct formed by coupling CHA with NQS is elucidated using NMR ((1)H and (13)C) and IR spectra, CHN analysis and mole ratio variation method.

RESUMEN

The electroanalytical chemistry of trace metals has progressed strongly with the development of cathodic stripping voltammetry (CSV) preceded by adsorption collection of organic metal complexes. A sensitive method for the determination of trace amount of chromium in gallium is described. Gallium is dissolved in sodium hydroxide containing hydrogen peroxide. The method is based on the catalytic activity of nitrate ions on the reduction of Cr(III)TTHA (triethylene tetramine-N,N,N',N'',N''',N'''-hexaacetic acid) complex. The sensitivity of this method is further improved by adsorption preconcentration of Cr(III)TTHA complex at a hanging mercury drop electrode (HMDE). The Cr(III) formed at the electrode surface by the reduction of Cr(VI), which is present in the bulk solution, is immediately complexed by TTHA. The adsorbed complex is then reduced at a peak potential of - 1.26 V, and the peak height of Cr(III) reduction is measured. The determination limit was restricted by the amount of chromium present in the reagent blank solution. The method is suitable for the determination of chromium at level as low as 0.2 mug g(-1) (with about 50 mg of sample) and a relative standard deviation of 15%.

RESUMEN

This study was conducted to evaluate the significance of genotype by environment (G x E) interactions for tropical poultry breeding. Three environmental conditions were considered: controlled normal-temperature (20 +/- 2 C, CN) and controlled high-temperature (32 C, CH) housing in Germany as well as natural open tropical housing in Malaysia (22 to 34 C, TO). Eighty-four sires were considered as genotypes. Their 5,352 progeny were tested simultaneously over three environments. For each sire, its part breeding value (BV) was estimated within each environment for each performance trait. Correlations between these BV for a pair of environments were used to estimate the magnitude of G x E interactions and the degree of relationship between them to demonstrate their implications on breeding strategies. Differences between observed and expected genetic correlations of BV for body weight, egg weight, egg number, egg mass, feed intake, and production efficiency as a fraction of the expected correlation were 5.1, 4.0, 36.7, 36.5, 17.7, and 31.6%, respectively, suggesting greater significance of G x E interactions for reproduction and production efficiency. The relationships between BV over the three environments were linear for most of the traits studied, but the coefficients of determination were dependent upon the magnitude of interactions involved. Relative efficiencies of indirect selection in CN or CH for performance in TO were also very low.

Asunto(s)

Cruzamiento , Pollos/genética , Temperatura , Animales , Huevos , Femenino , Genotipo , Masculino , Selección Genética