Habitat selection in rock pool corixids: the effect of local density on dispersal

The corixid species breeding in temporary rock pools of Baltic archipelago live in a highly fragmented and unpredictable habitat. Shallow rock pools can dry out and be refilled repeatedly during a summer causing high mortality of immatures. In deeper pools, young nymphs face intense competition by older stages including cannibalism. The adult corixids move frequently between rock pools and are thus able to use currently available habitat for reproduction. In this dispersal behaviour, the ability to assess the local population density and hence select the more suitable low density patches would be advantageous. We studied the effect of local population density on the frequency of dispersive flights of Arctocorisa carinata (Sahlberg) and Callicorixa producta (Reuter) experimentally, using rock pools from which nymphs of both species were removed. The dispersal rates of marked C. producta adults were significantly lower from experimental rock pools than from normal density controls, leading to a concentration of C. producta adults in the experimental rock pools. Indications of immigration rate differences between the experimental and control pools were also observed. No clear differences were found in the superior competitor A. carinata.     

Habitat characteristics contributing to local occupancy and habitat use in rock pool <Emphasis Type="Italic">Daphnia</Emphasis> metapopulations

The effects of invasive macrophytes, water level fluctuations and predation on freshwater unionids Pyganodon grandis and Utterbackia imbecillis were studied in three small impoundments in Northeastern Texas in 2003–2005. Mussel density was sampled with quadrats. Mortality, associated with the water level fluctuations and predation, was estimated by collecting dead shells on the shore at about two month intervals. In two ponds, horizontal distribution of unionids was limited by dense beds of invasive and noxious macrophytes (mainly Eurasian watermilfoil Myriophyllum spicatum and American lotus Nelumbo lutea): mussel densities were significantly lower in these macrophyte beds (P < 0.001). In the third pond with the lowest density of macrophytes (stonewort Chara sp.), unionids were distributed more evenly, and the average unionid biomass was the highest among all ponds studied. Vertical distribution of unionids in all ponds was likely limited by low oxygen at depth >2 m. The total amount of shells found on the shore per year varied from 0.1% to 28% of the total population in the pond and was negatively correlated with water level (r = −0.72 to −0.81, P < 0.005). Mammalian predators consumed up to 19% of the total unionid population and predation was facilitated by water level fluctuations. Handling editor: K. Martens     

Immunohistochemical localization of carbonic anhydrase isoenzymes VI, II, and I in human parotid and submandibular glands

Human salivary carbonic anhydrase (HCA VI) was purified by inhibitor affinity chromatography and its location in the human parotid and submandibular glands identified, using a polyclonal antiserum raised against the purified enzyme in rabbits in conjunction with the peroxidase-antiperoxidase complex method. The antibodies raised against the purified enzyme in rabbits did not crossreact with the HCA II or I. However, they slightly recognized human IgA; the antiserum was therefore absorbed with human IgA before immunohistochemical use. HCA VI-specific staining was detected in the cytoplasm and particularly in the secretory granules of the serous acinar cells of both parotid and submandibular glands, the staining of the secretory granules being most distinct in paraformaldehyde-fixed tissues. Some epithelial cells and the luminal content of the striated ducts also gave a specific HCA VI staining. Staining specific for HCA II was also found in the granules of the serous acinar cells, particularly in the submandibular gland when Carnoy fluid fixation was used. Slight HCA II-specific staining was also detected in the striated ductal cells in the Carnoy fluid-fixed specimens. No staining specific for HCA I was detected. The results indicate that the serous acinar cells in human parotid and submandibular glands contain abundant HCA II and HCA VI. Interestingly, only HCA VI is secreted into the saliva, although both enzymes appear to be located in structures resembling the secretory granules in the acinar cells. The enzymes probably form a mutually complementary system regulating the salivary buffer capacity.     

Phospholipid composition and external labeling of aminophospholipids of human En(a−) erythrocyte membranes which lack the major sialoglycoprotein (glycophorin a)

Erythrocytes of the rare human blood group En(a?) lack the major sialoglycoprotein, glycophorin A, and the cell population heterozygous for the En(a) antigen contain half the normal amount of glycophorin A. With such cells we have studied whether glycophorin A influences the phospholipid composition and the availability of aminophospholipids to external labeling reagents. We here demonstrate that the amounts of all phospholipids are closely similar in normal and variant membranes. However, using the amino-reactive reagent trinitrobenzenesulfonate, we show that phosphatidylethanolamine is more easily labeled in intact En(a?) cells as compared to normal cells, whereas phosphatidylethanolamine shows an intermediate labeling in En(a) heterozygous cells.     

T cell receptor expression can switch on and off at a posttranslational level.

The human T acute lymphocytic leukemia cell line, SUP-T13, is a mosaic of TCR/CD3+ and TCR/CD3- cells. Individual SUP-T13 cells can spontaneously switch on and off surface TCR/CD3 expression. This switching was demonstrated by culturing and analysis of single cell clones that were TCR/CD3+ or TCR/CD3-. The rate of switching is about 10(-2)/cell per generation in either direction. This is too high to be due to a spontaneous mutation event. Furthermore, switched cells can revert at similar rates, as demonstrated by repeated cloning and reanalysis. This makes it likely that a regulatory change is responsible for switching. In support of this, all known TCR/CD3 proteins are found intracellularly in TCR/CD3- cells, and they associate with each other as in TCR/CD3+ cells. Furthermore, no structural abnormalities of the TCR/CD3 chains can be seen in TCR/CD3- cells using two-dimensional electrophoresis. However, in these cells, the chains accumulate in great excess intracellularly. This accumulation is specific to the TCR/CD3 complex, as other glycoproteins are still expressed normally on the cell surface. Thus, there is regulation of TCR expression at a posttranslational level. These TCR/CD3- cells may lead to the identification of novel protein(s) involved in glycosylating, processing, or transporting the TCR/CD3 complex. Potential loss of TCR/CD3 expression may also limit the feasibility of TCR-based therapies for T cell leukemias.     

Skills training groups for men with ADHD in compulsory care due to substance use disorder: a feasibility study

Dialectical behavior therapy (DBT)-based skills training has been developed and previously evaluated for adults with ADHD in a psychiatric outpatient context. The aim of the present study was to evaluate the feasibility of DBT-based skills training as a voluntary intervention for men with ADHD in compulsory care due to severe substance abuse. Forty sufficiently detoxified men with ADHD in compulsory care due to life-threatening substance use disorder (SUD) were included in DBT-based skills training groups. Self- and staff-rating scales were administered before and after the treatment. The refusal rate was 42.9 %. Of those who started the DBT-based skills training, 70 % completed the treatment (attendance at ≥75 % of the sessions). The treatment acceptability was good. Both ADHD and psychiatric symptoms decreased from pre- to post-intervention in self-ratings, but not in staff ratings. The patients reported improved general well-being. The correlation between self- and staff ratings was poor. Motivation for voluntary nonpharmacological treatment was low in a compulsory care context. However, the results indicate that a DBT-based skills training program for adults with ADHD may be feasible for some patients with ADHD in combination with SUD in compulsory care, provided that considerable resources are allocated with adjustments to the target group and compulsory care context.     

Effects of gender,diet, exogenous melatonin and subchronic PCB exposure on plasma immunoglobulin G in mink

Effects of different fish-based diets (freshwater smelt, Baltic herring, marine herring/cod offal or their mixtures), gender, beta-glucan supplement, exogenous melatonin, and PCB exposure (Aroclor 1242((R)), 1 mg per animal per day in feed) on plasma immunoglobulin G (IgG) in the mink (Mustela vison) were studied. The aims of the study were to find out whether plasma IgG of the mink is affected by the subchronic PCB exposure, and whether biological, nutritional and hormonal effects are large enough to mask the possible IgG response. The concentration of IgG was determined using enzyme-linked immunosorbent assay (ELISA). Sexual dimorphism was detected, the males having higher levels of plasma IgG. In addition, melatonin tended to decrease IgG in females but not males. Diet also affected the humoral immune arm; the mixed-fish diets caused an unfavorable ratio of the oxidation products of lipids vs. vitamin E in liver, and resulted in low IgG concentration in plasma. In males fed Baltic herring, the beta-glucan supplement also lowered IgG levels. The PCBs failed to affect the plasma IgG of the smelt-fed female mink, and IgG concentration was not correlated with increased hepatic EROD activity or with the decreased total retinol in the liver of exposed mink. It is concluded that hormonal/seasonal and dietary factors affect the plasma IgG levels to such an extent that possible change in plasma IgG level due to PCBs in wild populations of mink is difficult to detect without a large amount of reference data.     

The effect of dietary phosphorus deficiency on the immune responses of European whitefish (Coregonus lavaretus L.)

Low phosphorous (P) feeds in aquaculture are recommended to reduce eutrophication of water systems. However, the feed should be adequate for normal growth and intact immune defence. Influence of low dietary P supply on non-specific and specific immune defence of European whitefish (Coregonus lavaretus) was studied in two trials. For Trial 1, a semi-purified, low-P diet was formulated and supplied with 0, 2.5, 5.0, 7.5, or 10.0 g P kg(-1)to obtain a P gradient of 4.4-14.9 g kg(-1)diet. Diets were fed to four replicate groups of fingerling whitefish for 42 days in a flow-through, freshwater system maintained at 15 degrees C. Fish fed with the P-unsupplemented diet had significantly lower plasma immunoglobulin M (IgM) levels than fish fed with the P-fortified diets (means 2.53 vs. 3.19 mg ml(-1); P=0.047). Plasma lysozyme activity did not differ between fish fed with the P-unsupplemented diet and fish fed with the P-fortified diets (means 21.8 vs. 25.5 U ml(-1); P=0.107). For Trial 2, fish were acclimated for 49 days by feeding the lowest or highest dietary P contents, and thereafter immunised with a single intraperitoneal injection of a novel antigen, bovine gamma globulin (BGG). A clear antibody response against BGG was elicited but the antibody levels did not differ between fish fed low-P or high-P contents. Similar to Trial 1, plasma IgM was lower in fish fed low-P diets, and low-P diet did not influence plasma lysozyme activity. In both trials the growth of fish, having received low-P diet, was significantly lowered. It is concluded that P deficiency has only minor effects on the immune parameters in whitefish, and the practical aquafeed with P contents sufficient for normal growth does not compromise immune functions of this species.     

Novel Mechanism of Arenavirus-Induced Liver Pathology

Viral hemorrhagic fevers (VHFs) encompass a group of diseases with cardinal symptoms of fever, hemorrhage, and shock. The liver is a critical mediator of VHF disease pathogenesis and high levels of ALT/AST transaminases in plasma correlate with poor prognosis. In fact, Lassa Fever (LF), the most prevalent VHF in Africa, was initially clinically described as hepatitis. Previous studies in non-human primate (NHP) models also correlated LF pathogenesis with a robust proliferative response in the liver. The purpose of the current study was to gain insight into the mechanism of liver injury and to determine the potential role of proliferation in LF pathogenesis. C57Bl/6J mice were infected with either the pathogenic (for NHPs) strain of lymphocytic choriomeningitis virus (LCMV, the prototypic arenavirus), LCMV-WE, or with the non-pathogenic strain, LCMV-ARM. As expected, LCMV-WE, but not ARM, caused a hepatitis-like infection. LCMV-WE also induced a robust increase in the number of actively cycling hepatocytes. Despite this increase in proliferation, there was no significant difference in liver size between LCMV-WE and LCMV-ARM, suggesting that cell cycle was incomplete. Indeed, cells appeared arrested in the G₁ phase and LCMV-WE infection increased the number of hepatocytes that were simultaneously stained for proliferation and apoptosis. LCMV-WE infection also induced expression of a non-conventional virus receptor, AXL-1, from the TAM (TYRO3/AXL/MERTK) family of receptor tyrosine kinases and this expression correlated with proliferation. Taken together, these results shed new light on the mechanism of liver involvement in VHF pathogenesis. Specifically, it is hypothesized that the induction of hepatocyte proliferation contributes to expansion of the infection to parenchymal cells. Elevated levels of plasma transaminases are likely explained, at least in part, by abortive cell cycle arrest induced by the infection. These results may lead to the development of new therapies to prevent VHF progression.