RESUMEN

The blowflies Lucilia spp. and Chryomya spp. feature prominently as a leading cause of myiasis and production losses in sheep in South Africa. With chemical means of preventing and treating blowfly strike being a common manner of control, new molecules or formulations effective against blowfly strike are needed as resistance becomes more of a problem. For this study we evaluated the potential of topical application of fluazuron on sheep as an additional means to control blowflies. When pure fluazuron was applied to raw meat at the recommended dose for cattle, significant effects on adult fly development were observed. However when applied topically to post-mortally collected sheep pelts at the same dose rate, no significant effects were observed on larval repellence or larval development with fly development progressing as expected. A subsequent pharmacokinetic study showed virtually no systemic absorption together with significant wool binding. Despite demonstrating that fluazuron was effective against blowfly larvae, wool binding of the molecule preclude its use.

Asunto(s)

Dípteros , Miasis , Enfermedades de las Ovejas , Animales , Calliphoridae , Bovinos , Larva , Miasis/tratamiento farmacológico , Miasis/prevención & control , Miasis/veterinaria , Compuestos de Fenilurea , Ovinos , Enfermedades de las Ovejas/tratamiento farmacológico , Enfermedades de las Ovejas/prevención & control

RESUMEN

Genetically engineered bacteria can be used for a wide range of applications, from monitoring environmental toxins to studying complex communication networks in the human digestive system. Although great strides have been made in studying single strains of bacteria in well-controlled microfluidic environments, there remains a need for tools to reliably control and measure communication between multiple discrete bacterial populations. Stable long-term experiments (e.g., days) with controlled population sizes and regulated input (e.g., concentration) and output measurements can reveal fundamental limits of cell-to-cell communication. In this work, we developed a microfluidic platform that utilizes a porous monolith to reliably and stably partition adjacent strains of bacteria while allowing molecular communication between them for several days. We measured small molecule production by the bacterial populations in response to stimuli using analytical chemistry methods and measured fluorescent output. The results are compared with communication and diffusion delay models. This porous monolith microfluidic system enables bacterial cell-to-cell communication assays with dynamic control of inputs, relatively long-term experimentation with no cross contamination, and stable bacterial population size. This system can serve as a valuable tool in understanding bacterial communication and improving biosensor design capabilities.

RESUMEN

Genetic variation in mitochondrial genes could underlie metabolic adaptations because mitochondrially encoded proteins are directly involved in a pathway supplying energy to metabolism. Macquarie perch from river basins exposed to different climates differ in size and growth rate, suggesting potential presence of adaptive metabolic differences. We used complete mitochondrial genome sequences to build a phylogeny, estimate lineage divergence times and identify signatures of purifying and positive selection acting on mitochondrial genes for 25 Macquarie perch from three basins: Murray-Darling Basin (MDB), Hawkesbury-Nepean Basin (HNB) and Shoalhaven Basin (SB). Phylogenetic analysis resolved basin-level clades, supporting incipient speciation previously inferred from differentiation in allozymes, microsatellites and mitochondrial control region. The estimated time of lineage divergence suggested an early- to mid-Pleistocene split between SB and the common ancestor of HNB+MDB, followed by mid-to-late Pleistocene splitting between HNB and MDB. These divergence estimates are more recent than previous ones. Our analyses suggested that evolutionary drivers differed between inland MDB and coastal HNB. In the cooler and more climatically variable MDB, mitogenomes evolved under strong purifying selection, whereas in the warmer and more climatically stable HNB, purifying selection was relaxed. Evidence for relaxed selection in the HNB includes elevated transfer RNA and 16S ribosomal RNA polymorphism, presence of potentially mildly deleterious mutations and a codon (ATP6113) displaying signatures of positive selection (ratio of nonsynonymous to synonymous substitution rates (dN/dS) >1, radical change of an amino-acid property and phylogenetic conservation across the Percichthyidae). In addition, the difference could be because of stronger genetic drift in the smaller and historically more subdivided HNB with low per-population effective population sizes.

Asunto(s)

Evolución Molecular , Flujo Genético , Genoma Mitocondrial , Percas/genética , Selección Genética , Animales , Australia , Teorema de Bayes , Clima , Codón , Especies en Peligro de Extinción , Agua Dulce , Repeticiones de Microsatélite , Filogenia , ARN Ribosómico 16S/genética , ARN de Transferencia/genética

RESUMEN

Climatic differences across a taxon's range may be associated with specific bioenergetic demands and may result in genetics-based metabolic adaptation, particularly in aquatic ectothermic organisms that rely on heat exchange with the environment to regulate key physiological processes. Extending down the east coast of Australia, the Great Dividing Range (GDR) has a strong influence on climate and the evolutionary history of freshwater fish species. Despite the GDR acting as a strong contemporary barrier to fish movement, many species, and species with shared ancestries, are found on both sides of the GDR, indicative of historical dispersal events. We sequenced complete mitogenomes from the four extant species of the freshwater cod genus Maccullochella, two of which occur on the semi-arid, inland side of the GDR, and two on the mesic coastal side. We constructed a dated phylogeny and explored the relative influences of purifying and positive selection in the evolution of mitogenome divergence among species. Results supported mid- to late-Pleistocene divergence of Maccullochella across the GDR (220-710 thousand years ago), bringing forward previously reported dates. Against a background of pervasive purifying selection, we detected potentially functionally relevant fixed amino acid differences across the GDR. Although many amino acid differences between inland and coastal species may have become fixed under relaxed purifying selection in coastal environments rather than positive selection, there was evidence of episodic positive selection acting on specific codons in the Mary River coastal lineage, which has consistently experienced the warmest and least extreme climate in the genus.

Asunto(s)

Evolución Molecular , Peces/genética , Genoma Mitocondrial , Selección Genética , Animales , Australia , Teorema de Bayes , Clima , Codón , ADN Mitocondrial , Especies en Peligro de Extinción , Agua Dulce , Geografía , Modelos Genéticos , Filogenia , Análisis de Secuencia de ADN

RESUMEN

Clostridium perfringens strain JJC is an effective biohydrogen and biochemical producer that was isolated from landfill leachate sludge. Here, we present the assembly and annotation of its genome, which may provide further insights into the gene interactions involved in efficient biohydrogen production.

RESUMEN

Clostridium bifermentans strain WYM is an effective biohydrogen producer isolated from landfill leachate sludge. Here, we present the assembly and annotation of its genome, which may provide further insights into the metabolic pathways involved in efficient biohydrogen production.

RESUMEN

Clostridium sp. strain Ade.TY is potentially a new biohydrogen-producing species isolated from landfill leachate sludge. Here we present the assembly and annotation of its genome, which may provide further insights into its gene interactions for efficient biohydrogen production.

RESUMEN

San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads from urban runoff. Atmospheric deposition is a lower priority for source control in the Bay Area due to a combination of a lack of major local sources. Internal net production of MeHg is the dominant source of MeHg that enters the food web. Controlling internal net production is the second primary management approach, and has the potential to reduce food web MeHg in some habitats more effectively and within a much shorter time-frame. Controlling net MeHg production and accumulation in the food web of upstream reservoirs and ponds is very promising due to the many features of these ecosystems that can be manipulated. The most feasible control options in tidal marshes relate to the design of flow patterns and subhabitats in restoration projects. Options for controlling MeHg production in open Bay habitat are limited due primarily to the highly dispersed distribution of Hg throughout the ecosystem. Other changes in these habitats may also have a large influence on food web MeHg, including temperature changes due to global warming, sea level rise, food web alterations due to introduced species and other causes, and changes in sediment supply. Other options for reducing or mitigating exposure and risk include controlling bioaccumulation, cleanup of contaminated sites, and reducing other factors (e.g., habitat availability) that limit at-risk wildlife populations.

Asunto(s)

Estuarios , Cadena Alimentaria , Compuestos de Metilmercurio/metabolismo , Agua de Mar/química , Contaminantes Químicos del Agua/metabolismo , Animales , Exposición a Riesgos Ambientales , Humanos

RESUMEN

SETTING: An inner city neighborhood in Houston, Texas, known for a high rate of drug use. OBJECTIVE: To determine the prevalence of latent tuberculosis infection (LTBI) using the QuantiFERON-TB Gold (QFT-G) test, the TSPOT.TB test and the tuberculin skin test (TST) in drug users and to evaluate the performance of the QFT-G and TSPOT.TB tests vs. the TST. DESIGN: Cross-sectional study. Bivariate and multivariate logistic regression analyses were used to determine risks associated with each test outcome. RESULTS: The prevalence of LTBI in 119 drug users studied was 28% by TST and 34% by QFT-G and T-SPOT.TB. Kappa statistics indicated fair to moderate concordance between QFT-G and TSPOT.TB vs. TST. About one-fifth of the population that tested negative with TST was positive with either QFT-G or T-SPOT.TB. On multivariate analysis, the likelihood of testing QFT-positive or T-SPOT.TB-positive increased by 8% and 6%, respectively, for every year of age; TST positivity was associated with smoking crack at home; being Caucasian or having a history of alcohol use was positively associated with a positive T-SPOT.TB test. CONCLUSION: Interferon-gamma release assays (IGRAs) are superior to the TST in drug users with a higher prevalence of LTBI. Future studies need to assess the predictive value of IGRAs on the progression from LTBI to active TB in high-risk populations.

Asunto(s)

Interferón gamma/metabolismo , Trastornos Relacionados con Sustancias/complicaciones , Tuberculosis/diagnóstico , Adolescente , Adulto , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tuberculosis/complicaciones

RESUMEN

There is considerable scope for genetic improvement of cultured blacklip abalone Haliotis rubra in Australia using molecular marker-assisted, selective-breeding practices. Such improvement is dependent on the availability of primary genetic resources, such as a genetic linkage map. This study presents a first-generation linkage map of H. rubra, containing 122 microsatellite markers typed in a single full-sib family. These loci mapped to 17 and 20 linkage groups for the male and female respectively, and when aligned, the consensus map represented 18 linkage groups. The male linkage map contained 102 markers (one unlinked) covering 621 cM with an average intermarker spacing of 7.3 cM, and the female map contained 98 markers (eight unlinked) covering 766 cM with an average intermarker spacing of 9.8 cM. Analysis of markers informative in both parents showed a significantly higher recombination rate in the female parent, with an average male-to-female recombination ratio of 1:1.45 between linked pairs of markers. This linkage map represents a significant advancement in the genetic resource available for H. rubra and provides a framework for future quantitative trait loci mapping and eventual implementation of marker-assisted selection.

Asunto(s)

Mapeo Cromosómico , Gastrópodos/genética , Repeticiones de Microsatélite , Animales , Australia , Femenino , Genoma , Masculino , Recombinación Genética , Factores Sexuales

RESUMEN

The complete mitochondrial DNA sequence was determined for the mantid shrimp Harpiosquilla harpax. These data demonstrate that the H. harpax mitochondrial genome is a 15,714 bp circular molecule and encodes the typical 37 metazoan mitochondrial genes (13 protein-coding, 22 tRNA, and two rRNA genes). The gene arrangement of H. harpax is consistent with that of the putative arthropod ancestral gene order as depicted by Limulus polyphemus. H. harpax was employed as an outgroup taxon for a phylogenetic investigation of the Decapoda using sequences from complete mitochondrial genomes. Whilst our results are largely in agreement with current taxonomic treatments, the relationships indicated among the reptantian decapods are novel. Our results provide strong statistical support for a sister-group relationship between the Achelata and the Astacida. These findings not only refute previous phylogenetic hypotheses, but also have serious implications for the interpretation of morphological and developmental evolution in the Decapoda. In addition we also investigated the effects of outgroup selection on the resolution of ingroup relationships. We found outgroup choice to significantly influence tree topology thus reinforcing the importance of appropriate outgroup selection in phylogenetic studies.

Asunto(s)

Crustáceos/genética , ADN Mitocondrial/genética , Genoma , Filogenia , Animales , Secuencia de Bases , Clonación Molecular , Crustáceos/clasificación , Cartilla de ADN , Conformación de Ácido Nucleico , Reacción en Cadena de la Polimerasa , ARN Ribosómico/química , ARN Ribosómico/genética , ARN de Transferencia/química , ARN de Transferencia/genética

RESUMEN

Direct sequencing of mitochondrial DNA (mtDNA) D-loop (745 bp) and MTATPase6/MTATPase8 (857 bp) regions was used to investigate genetic variation within common carp and develop a global genealogy of common carp strains. The D-loop region was more variable than the MTATPase6/MTATPase8 region, but given the wide distribution of carp the overall levels of sequence divergence were low. Levels of haplotype diversity varied widely among countries with Chinese, Indonesian and Vietnamese carp showing the greatest diversity whereas Japanese Koi and European carp had undetectable nucleotide variation. A genealogical analysis supports a close relationship between Vietnamese, Koi and Chinese Color carp strains and to a lesser extent, European carp. Chinese and Indonesian carp strains were the most divergent, and their relationships do not support the evolution of independent Asian and European lineages and current taxonomic treatments.

Asunto(s)

Secuencia de Bases/genética , Carpas/genética , ADN Mitocondrial , Variación Genética , Animales , Carpas/clasificación , ADN Mitocondrial/aislamiento & purificación , Haplotipos/genética , Filogenia , Reacción en Cadena de la Polimerasa , Análisis de Secuencia de ADN

RESUMEN

Non-coding copies of fragments of the mitochondrial genome translocated to the nucleus or pseudogenes are being found with increasing frequency in a diversity of organisms. As part of a study to evaluate the utility of a range of mitochondrial gene regions for population genetic and systematic studies of the Australian freshwater crayfish, Cherax destructor (the yabby), we report the first detection of Cytochrome b (Cyt b) pseudogenes in crustaceans. We amplified and sequenced fragments of the mitochondrial Cyt b gene from 14 individuals of C. destructor using polymerase chain reaction (PCR) with primers designed from conserved regions of Penaeus monodon and Drosophila melanogaster mitochondrial genomes. The phylogenetic tree produced from the amplified fragments using these primers showed a very different topology to the trees obtained from sequences from three other mitochondrial genes, suggesting one or more nuclear pseudogenes have been amplified. Supporting this conclusion, two highly divergent sequences were isolated from each of two single individuals, and a 2 base pair (bp) deletion in one sequence was observed. There was no evidence to support inadvertent amplification of parasite DNA or contamination of samples from other sources. These results add to other recent observations of pseudogenes suggesting the frequent transfer of mitochondrial DNA (mtDNA) genes to the nucleus and reinforces the necessity of great care in interpreting PCR-generated Cyt b sequences used in population or evolutionary studies in freshwater crayfish and crustaceans more generally.

Asunto(s)

Astacoidea/genética , Grupo Citocromo b/genética , Mitocondrias/enzimología , Reacción en Cadena de la Polimerasa/veterinaria , Animales , Secuencia de Bases , Datos de Secuencia Molecular , Homología de Secuencia de Ácido Nucleico , Especificidad de la Especie

RESUMEN

Monitoring the release and uptake of catecholamines from terminals in weakly innervated brain regions is an important step in understanding their importance in normal brain function. To that end, we have labeled brain slices from transgenic mice that synthesize placental alkaline phosphatase (PLAP) on neurons containing tyrosine hydroxylase with antibody-fluorochrome conjugate, PLAP-Cy5. Excitation of the fluorochrome enables catecholamine neurons to be visualized in living tissue. Immunohistochemical fluorescence with antibodies to tyrosine hydroxylase and dopamine beta-hydroxylase revealed that the PLAP labeling was specific to catecholamine neurons. In the prefrontal cortex (PFC), immunohistochemical fluorescence of the PLAP along with staining for dopamine transporter (DAT) and norepinephrine transporter (NET) revealed that all three exhibit remarkable spatial overlap. Fluorescence from the PLAP antibody was used to position carbon-fiber microelectrodes adjacent to catecholamine neurons in the PFC. Following incubation with L-DOPA, catecholamine release and subsequent uptake was measured and the effect of uptake inhibitors examined. Release and uptake in NET and DAT knockout mice were also monitored. Uptake rates in the cingulate and prelimbic cortex are so slow that catecholamines can exist in the extracellular fluid for sufficient time to travel approximately 100 microm. The results support heterologous uptake of catecholamines and volume transmission in the PFC of mice.

Asunto(s)

Catecolaminas/metabolismo , Glicoproteínas de Membrana , Proteínas de Transporte de Membrana , Proteínas del Tejido Nervioso , Corteza Prefrontal/metabolismo , Simportadores , Fosfatasa Alcalina/biosíntesis , Fosfatasa Alcalina/genética , Fosfatasa Alcalina/inmunología , Animales , Anticuerpos Monoclonales , Carbocianinas , Proteínas Portadoras/antagonistas & inhibidores , Proteínas Portadoras/genética , Proteínas Portadoras/inmunología , Cromatografía Líquida de Alta Presión , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática , Estimulación Eléctrica , Electroquímica , Técnica del Anticuerpo Fluorescente , Giro del Cíngulo/metabolismo , Sistema Límbico/metabolismo , Ratones , Ratones Noqueados , Ratones Transgénicos , Microscopía Confocal , Inhibidores de la Monoaminooxidasa/farmacología , Neuronas/enzimología , Proteínas de Transporte de Noradrenalina a través de la Membrana Plasmática , Placenta/enzimología , Tirosina 3-Monooxigenasa/análisis

RESUMEN

Many studies have found that infant-directed (ID) speech has higher pitch, has more exaggerated pitch contours, has a larger pitch range, has a slower tempo, and is more rhythmic than typical adult-directed (AD) speech. We show that the ID speech style reflects free vocal expression of emotion to infants, in comparison with more inhibited expression of emotion in typical AD speech. When AD speech does express emotion, the same acoustic features are used as in ID speech. We recorded ID and AD samples of speech expressing love-comfort, fear, and surprise. The emotions were equally discriminable in the ID and AD samples. Acoustic analyses showed few differences between the ID and AD samples, but robust differences across the emotions. We conclude that ID prosody itself is not special. What is special is the widespread expression of emotion to infants in comparison with the more inhibited expression of emotion in typical adult interactions.

Asunto(s)

Emociones , Relaciones Madre-Hijo , Acústica del Lenguaje , Conducta Verbal , Adulto , Femenino , Humanos , Lactante , Masculino , Espectrografía del Sonido

RESUMEN

PURPOSE: Our purpose was to assess how the number of embryos transferred can be adjusted to limit multiple gestations. METHODS: A retrospective analysis of 535 consecutive embryo transfers for the years 1991-1993 was conducted. RESULTS: Fewer than three embryos were associated with a low pregnancy rate. Pregnancy rates were highest in women less than 35 when four or more embryos were transferred. With four or more embryos, multiple gestation pregnancy correlated with the number of high-quality embryos transferred. The risk of triplets and quadruplets was greatest for women less than 40. CONCLUSIONS: Multiple-embryo transfer carries a risk of plural gestation. The risk of multiple pregnancy cannot be eliminated without decreasing the pregnancy rate. The risk of high-order multiple pregnancy was best correlated with the number of good-quality embryos transferred. While all are at risk, patients younger than 40 were at highest risk.

Asunto(s)

Transferencia de Embrión/métodos , Fertilización In Vitro/métodos , Embarazo Múltiple , Adulto , Femenino , Humanos , Embarazo , Índice de Embarazo , Estudios Retrospectivos

RESUMEN

OBJECTIVE: Our objective was to evaluate the efficacy of Synthetic Serum Substitute (Irvine Scientific--Materials Section, Santa Ana, CA), a globulin-enriched protein preparation containing human serum albumin for supplementation of IVF culture media. DESIGN: We retrospectively analyzed IVF cycles performed at MacDonald Womens Hospital between January 1992 and November 1994. IVF cycles were reviewed and classified according to the nature of protein supplementation used in the embryo culture medium. Three protein supplements utilized during this time period were compared: Synthetic Serum Substitute (SSS), Plasmanate (PL), and maternal serum (MS). RESULTS: Although clinical pregnancy rates among the three treatment groups were not statistically different, there was a definite trend toward a higher pregnancy rate with SSS supplementation (SSS, 38.2%; MS, 28.0%; and PL, 24.9%). Embryos grown in SSS-supplemented culture media had a significantly higher implantation rate (17.8 vs 10.4 and 10.3%, respectively, for MS and PL). Preliminary data also suggest that human embryo development and blastulation in vitro were enhanced by this protein supplement. CONCLUSIONS: The higher implantation rate with SSS suggests that it may be superior to both maternal serum and Plasmanate in supporting human embryo development in vitro. Whether blastocysts derived from PL- and SSS-supplemented media are able to implant and give rise to clinical pregnancies remains to be seen.

Asunto(s)

Medios de Cultivo/química , Fertilización In Vitro/métodos , Sustitutos del Plasma/química , Adulto , alfa-Globulinas/metabolismo , beta-Globulinas/metabolismo , Blastocisto/metabolismo , Proteínas Sanguíneas , Transferencia de Embrión , Femenino , Humanos , Infertilidad/metabolismo , Sustitutos del Plasma/metabolismo , Embarazo , Resultado del Embarazo , Proteínas/química , Estudios Retrospectivos , Albúmina Sérica/metabolismo , Albúmina Sérica Humana , Seroglobulinas

RESUMEN

BACKGROUND: Heterotopic pregnancy occurs in about 1% of pregnancies achieved with assisted reproductive technologies. The incidence of cornual pregnancy is approximately 1% of all ectopics. CASES: Two patients became pregnant after treatment with IVF-ET. Both presented during the first trimester with evidence of an acute abdomen and ultrasonographic suspicion for cornual heterotopic pregnancies. The diagnoses were confirmed by laparoscopy, and treatment was undertaken with laparotomy with cornual resection. Both delivered viable infants by cesarean section; the first patient delivered a twin gestation at 28 weeks and the second a singleton pregnancy at 37 weeks. All infants were doing well two months after delivery. CONCLUSION: Abnormal pregnancies can be detected after IVF-ET with careful follow-up, transvaginal ultrasound studies, serial hCG measurements and pelvic examinations. Cornual heterotopic pregnancies can be successfully treated with cornual resection, especially in cases presenting during the second trimester or when there is clinical evidence of an acute abdomen. All deliveries should be performed by cesarean section at term prior to labor or when tocolysis for premature labor has failed.

Asunto(s)

Transferencia de Embrión/efectos adversos , Fertilización In Vitro/efectos adversos , Embarazo Ectópico/etiología , Femenino , Humanos , Embarazo , Embarazo Ectópico/diagnóstico , Embarazo Ectópico/cirugía

RESUMEN

The kinetics of refolding of ribonuclease A were monitored by the return of catalytic activity and inhibitor binding at -15 degrees C in 35% methanol cryosolvent at pH* 3.0 and 6.0. Catalytic activity was measured with cytidine 2',3'-cyclic monophosphate as substrate; inhibitor binding was determined with the competitive inhibitor cytidine 2'-monophosphate. Biphasic kinetics were observed at pH* 3.0 for both return of catalytic activity and inhibitor binding. At pH* 6.0 the rate of return of catalytic activity was monophasic, whereas that of inhibitor binding was biphasic. For both inhibitor binding and catalytic activity one of the observed rates was pH-dependent. Full return of catalytic activity was obtained at the completion of the refolding process. The observations are interpreted in terms of two parallel pathways of refolding for slow-refolding ribonuclease, with several native-like, partially folded intermediate states on the minor slow-refolding pathway. Of particular note is the presence of at least one such species that has inhibitor-binding capacity but not catalytic activity. This may be rationalized in terms of the known native structure. In addition, an intermediate is postulated which has the incorrect Pro-93 conformation and only partial catalytic activity (42% of the native). The slowest observed transient is attributed to the isomerization of this proline residue and return of full catalytic activity.

Asunto(s)

Ribonucleasa Pancreática/metabolismo , Sitios de Unión , CMP Cíclico/metabolismo , Congelación , Concentración de Iones de Hidrógeno , Cinética , Unión Proteica , Conformación Proteica , Desnaturalización Proteica

Asunto(s)

Linfocitos , Tejido Linfoide/citología , Animales , Reacciones Antígeno-Anticuerpo , Autorradiografía , Diferenciación Celular , Movimiento Celular , Femenino , Técnicas In Vitro , Ganglios Linfáticos/citología , Masculino , Parabiosis , Ratas , Bazo/citología , Timidina/metabolismo , Tritio , Uridina/metabolismo