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Wild-caught European perch (Perca fluviatilis) were exposed in the laboratory to untreated bleached pulp and paper mill effluent in two separate experiments. The first experiment was conducted at 7-8°C using effluent concentrations of 5 and 10%, and the second experiment was conducted at ambient river temperature of 4-20°C using an effluent concentration of 1%. Trichodinid ciliates were identified and enumerated at the end of the exposure using a mucus subsampling technique from gill and skin as well as a formalin immersion technique, which provided total counts on each fish. Four different trichodinid species were identified on the fish. Prevalence of infection, mean number, and mean density of Trichodina spp. decreased on fish exposed to effluents compared with controls. Prevalence of infection, mean number, and mean density of Trichodinella epizootica decreased on fish exposed to 5% and 10% effluents but increased on fish exposed to 1% effluents compared with controls. These results demonstrate that trichodinid ciliates vary in their susceptibility to at least certain types of contaminants and cautions against using trichodinids as environmental indicators without delineating species.

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Ecological changes affect pathogen epidemiology and evolution and may trigger the emergence of novel diseases. Aquaculture radically alters the ecology of fish and their pathogens. Here we show an increase in the occurrence of the bacterial fish disease Flavobacterium columnare in salmon fingerlings at a fish farm in northern Finland over 23 years. We hypothesize that this emergence was owing to evolutionary changes in bacterial virulence. We base this argument on several observations. First, the emergence was associated with increased severity of symptoms. Second, F. columnare strains vary in virulence, with more lethal strains inducing more severe symptoms prior to death. Third, more virulent strains have greater infectivity, higher tissue-degrading capacity and higher growth rates. Fourth, pathogen strains co-occur, so that strains compete. Fifth, F. columnare can transmit efficiently from dead fish, and maintain infectivity in sterilized water for months, strongly reducing the fitness cost of host death likely experienced by the pathogen in nature. Moreover, this saprophytic infectiousness means that chemotherapy strongly select for strains that rapidly kill their hosts: dead fish remain infectious; treated fish do not. Finally, high stocking densities of homogeneous subsets of fish greatly enhance transmission opportunities. We suggest that fish farms provide an environment that promotes the circulation of more virulent strains of F. columnare. This effect is intensified by the recent increases in summer water temperature. More generally, we predict that intensive fish farming will lead to the evolution of more virulent pathogens.

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In benthic habitats, predators can generally not be detected visually, so olfaction may be particularly important for inducing anti-predation behaviors in prey organisms. Manipulative parasites infecting benthic hosts could suppress these responses so as to increase the probability of predation and thus trophic transmission. We studied how infection with the acanthocephalan Echinorhynchus borealis affects the response of the benthic amphipod Pallasea quadrispinosa to water conditioned by burbot (Lota lota), the parasite's definitive host. In normal lake water, refuge use by infected and uninfected amphipods was similar, but when exposed to burbot-conditioned water, uninfected amphipods spent much more time hiding than infected amphipods. Thus, rather than affecting ambient hiding behavior, E. borealis infection seems to alter host response to a predator. A group of amphipods sampled from a postglacial spring that is devoid of fish predators exhibited only a weak response to burbot-conditioned water, perhaps suggesting these anti-predator behaviors are costly to maintain. The hiding behavior of spring and infected amphipods was very similar. If the reduced refuge use by the spring amphipods reflects adaptation to a predator-free environment, this indicates that E. borealis severely weakens its host's anti-predator behavior. Presumably this increases the likelihood of parasite transmission.

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Chemokines and their receptors participate in the development of multiple sclerosis (MS) by guiding immune cells into the brain tissue. A CCR5 Delta32 deletion mutation abolishes functional CCR5 on the cell surface and may reduce cell entry into the lesion sites. To analyse the significance of this mutation in MS, we compared the frequencies of CCR5 genotype in peripheral blood mononuclear cells from 89 MS patients and 119 healthy controls. The CCR5 genotype was further compared with the CCR5 RNA and surface protein expression in 48 MS patients and their controls. In all MS patients, the Delta32/32 genotype was found with 6.7% frequency, whereas it was present only in 0.8% of the controls (6/89 vs 1/119, P = 0.01). Specifically, the Delta32/Delta32 genotype was increased (11.5%, P = 0.05) among primary progressive MS patients, whereas it was present only in 4.8% in other MS subtypes and only in 0.8% of the controls. The amount of CCR5 protein on CD4(+) cells analysed in 48 MS patients (nine primary progressive MS, 18 secondary progressive MS, 21 relapsing-remitting MS) and 13 controls decreased with genotype, being 8.9% in wt/wt, 7.7% in wt/Delta32 and 4.3% in Delta32/Delta32. CCR5 surface expression analysed on these 48 MS patients and 13 controls was significantly decreased in Delta32/Delta32 MS patients as compared with that in wt/wt genotype individuals (P = 0.004). The significantly increased number of Delta32/Delta32 individuals among our MS patients suggests that this genotype could contribute as a general risk factor for MS. However, neither the levels of RNA or surface protein correlated with MS subtype, neurological disability as expressed by expanded disability status scale, or disease progression index. Our results suggest that the lack of CCR5 does not protect from MS, but rather it may predispose to the chronic course of the disease. This would further imply that in view of the redundancy in the chemokine system, CCR5 ligands must be assumed to function through other closely related chemokine receptors.

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In inflamed colonic mucosa, the equilibrium between absorptive and secretory functions for electrolyte and salt transport is disturbed. We compared the expression of three major mediators of the intestinal salt transport between healthy and inflamed colonic mucosa to understand the pathophysiology of diarrhea in inflammatory bowel disease. Expression levels of the cystic fibrosis transmembrane regulator (CFTR) (Cl- channel), SLC26A3 (Cl-/HCO exchanger) and SLC9A3 (Na+/H+ exchanger) mRNAs were measured by real-time quantitative RT-PCR in peroperative colonic samples from controls (n = 4) and patients with ulcerative colitis (n = 10). Several samples were obtained from each individual. Tissue samples were divided into three subgroups according to their histological degree of inflammation. Expression of CFTR and SLC26A3 proteins were determined by immunohistochemistry and Western blotting from the same samples, respectively. Increased expression of CFTR mRNA was observed in all three groups of affected tissue samples, most pronounced in mildly inflamed colonic mucosa (5-fold increase in expression; P < 0.001). The expression of the CFTR protein was detected from health and inflamed colon tissue. Although the expression of the SLC26A3 mRNA was significantly decreased in severe ulcerative colitis (P < 0.05), the SLC26A3 protein levels remained unchanged in all groups. The expression of SLC9A3 mRNA was significantly changed between the mild and severe groups. Intestinal inflammation modulates the expression of three major mediators of intestinal salt transport and may contribute to diarrhea in ulcerative colitis both by increasing transepithelial Cl- secretion and by inhibiting the epithelial NaCl absorption.

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Anhidrotic ectodermal dysplasia (EDA) is an X-linked disorder characterized by abnormal development of ectoderm and its appendices. The EDA gene encodes different isoforms of ectodysplasin, a transmembrane protein. The two longest isoforms, ectodysplasin-A1 and -A2, which differ by an insertion of two amino acids, are trimeric type II membrane proteins with an extracellular portion containing a short collagenous domain and a TNF ligand motif in the C-terminal region. We show that ectodysplasin is released from cells to the culture medium. Deletion constructs were used to localize the cleavage site and show that the putative recognition sequence of a furin-like enzyme is needed for the cleavage. Some EDA patients have missense mutations affecting this recognition sequence, suggesting that cleavage has biological significance in vivo. EDAR, a recently cloned member of the TNFR family and the product of the downless gene, is able to co-precipitate ectodysplasin, confirming that they form a ligand-receptor pair. In situ hybridization and immunostaining studies show that ectodysplasin and EDAR are expressed in adjacent or partially overlapping layers in the developing human skin. We conclude that as a soluble ligand, ectodysplasin is able to interact with EDAR and mediate signals needed for the development of ectodermal appendages.

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We used nestedness analysis to seek non-random patterns in the structure of component communities of metazoan parasites collected from 31 sympatric fish species from the northeastern Bothnian Bay, the most oligohaline area of the Baltic Sea. Only 8 marine parasite species were found among the 63 species recorded, although some marine fish species reproduce in the bay and others occasionally visit the area. Marine parasite species can utilize both freshwater and marine fish species as intermediate or final hosts, and marine fish can harbour freshwater parasite species. This exchange of parasite species between marine and freshwater fish has probably resulted from ecological factors acting over short time scales rather than from evolutionary processes acting over longer time; the key factor probably being the immediate presence of suitable intermediate and definitive hosts. Marine fish were expected to harbour species-poor parasite communities consisting mainly of generalists acquired from the sympatric freshwater fish species, which would result in a nested pattern among the different component communities. However, an anti-nested pattern was found in the component communities of metazoan parasites of fishes from the Bothnian Bay. A likely explanation for the observed pattern is that there are specialist parasite species, the majority of which are cestodes, in some of the freshwater fish species which otherwise have depauperate parasite communities.

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Some parasites have been shown to manipulate host behavior so that parasite transmission to the next host is enhanced. Infection with Triaenophorus crassus Forel (Cestoda) caused alterations in the activity and microhabitat selection of the first intermediate host Cyclops strenuus Fischer (Copepoda) in the laboratory. Infected copepods made more starts to swim but spent less time swimming than uninfected copepods. These changes were independent of the intensity of infection. In a water column illuminated from above, infected copepods approached the surface, whereas uninfected ones remained close to the bottom. In the dark both infected and uninfected copepods stayed near the bottom. Finally, infection with T. crassus increased the probability of C. strenuus being eaten by the second intermediate host, whitefish (Coregonus lavaretus L. s.l.), in the laboratory. In experimental infections, 10-day-old procercoids had significantly lower infectivity for whitefish than older (12-, 14-, and 21-day-old) procercoids. Behavioral changes were detected in infected copepods containing procercoids 12 days old or older but not in experiments with 10-day-old procercoids. These results may indicate that T. crassus changes the behavior of the copepod host only after it has become infective to the next host, which is consistent with the active manipulation hypothesis.

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As a superior competitor for planktonic food, vendace (Coregonus albula), when abundant, is expected to displace whitefish (Coregonus lavaretus) from feeding on plankton and to force it to rely more on benthic food. The predicted result would be a reduced abundance of the copepod-transmitted cestode Triaenophorus crassus in whitefish, but an increase in the abundance of the nematode Cystidicola farionis transmitted via benthic amphipods. We studied the occurrence of both parasites in whitefish during 1991-1996 in three interconnected areas at Lake Saimaa, Finland, where the densities of the vendace stocks varied due to natural fluctuation in year-class strengths. In accordance with our hypothesis, some indication of the effect of the density of the vendace population on abundance of C. farionis infection in whitefish was found, but not in the case of T. crassus. Only 0.2% of vendace were infected with T. crassus, while up to 100% of the whitefish in the yearly samples harboured the parasite. In further experiments we clarified which copepod species in Lake Saimaa act as first intermediate hosts of T. crassus, and verified from stomach samples the exposure of both whitefish and vendace to those species. Experimental infections indicated that the infectivity of T. crassus is lower for vendace than for whitefish. We suggest that the reason why vendace stock density does not affect T. crassus infection in whitefish is that T. crassus is transmitted in littoral areas during a short period in spring. At that time of the year copepods are abundant and available to both whitefish and vendace, but since the parasite is less infective to vendace. they do not become infected. At other times of the year, dense vendace stocks may force whitefish to shift to benthic food, which includes amphipods transmitting C. farionis. During vendace stock decline, whitefish may, however, continue to feed on plankton and avoid exposure to C. farionis.

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Factors affecting the abundance of Triaenophorus crassus and Triaenophorus nodulosus procercoids in their copepod first intermediate host, Cyclops strenuus, and effects of infection on feeding behaviour, reproduction and survival of the host were studied experimentally. When exposed to the same number of coracidia, copepods harboured considerably less procercoids in the trials where ciliates or Artemia salina nauplii were given as alternative food items. The prevalence of infection was higher in adult copepods as compared with copepodite stage IV and stage V, and higher in stage V than in stage IV. The prevalences in adult females and males did not differ significantly from each other. The frequency of females carrying egg sacs was lower among infected than among exposed uninfected and unexposed copepods. The rate of feeding on Artemia nauplii remained at the same level in uninfected copepods, but decreased strongly in infected copepods during 7 days p.i. The survival of unexposed, exposed uninfected and infected copepods did not differ significantly from each other for the first 11 days post-exposure, but the mortality of infected copepods increased significantly after 3 weeks post-exposure. However, the rate of development and mortality of copepods might have been affected by the apparently arrested development of stage IV copepodites found in the experiment. Some of the contradictions between these results and earlier observations are suggested to be caused by the differences in the duration of exposure, intensity of infection and duration of observation post-exposure in the present study as compared with other experiments.

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Photoacoustic overtone spectra of monobromoacetylene, HCCBr, have been recorded in the wavenumber region 11600-13400 cm-1 using a titanium:sapphire ring laser spectrometer. All together, eight overtone bands of HCC79Br and eight bands of HCC81Br have been observed in the rotational analysis. A Fermi resonance model based on conventional normal coordinate theory has been used to vibrationally assign the rotationally analyzed bands. The resonance model employed reproduces well the observed vibrational band origins and rotational constants. Copyright 1998 Academic Press. Copyright 1998Academic Press

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The influence of human follicular fluid from mature and immature oocytes on the maturation of rabbit oocytes under in-vitro conditions was examined. The human follicular fluids were obtained in the course of laparoscopies for extracorporeal insemination and separated into the categories mature and immature ova. In cases of normal early embryonal development the follicular fluid was termed "follicular fluid of a mature ovum"; if the ova were immature or degenerated the fluid was termed "follicular fluid of an immature ovum". Rabbit oocytes were obtained 3 hours after administration of P-LH and immediately cultivated in 3 different culture media for 7 hours. Only 6 out of 50 rabbit oocytes cultivated in Brackett's Defined Medium with the addition of 20% follicular fluid from an immature human ovum for 7 hours reached prometaphase II to metaphase II. This corresponds to a rate of 12%; on the other hand, with the addition of follicular fluid from a mature ovum 18 out of 50 oocytes reached the same phase, i.e., a rate of 36%. This difference is statistically significant (p less than 0.01). Brackett's Defined Medium with no fluid added was used as a control. Only 5 out of 50 oocytes managed to reach prometaphase II to metaphase II. The rate in this case was 10%. In order to prove that the rabbit oocytes were in the chromatin consolidation phase, they were fixed immediately after being obtained (3 hours after P-LH administration) and stained in 5% Giemsa solution. All of the oocytes (31) were in the chromatin consolidation phase.(ABSTRACT TRUNCATED AT 250 WORDS)

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