Habitat-use patterns of the coypuMyocastor coypus in an urban wetland of its original distribution

The coypuMyocastor coypus Molina, 1782 is a semi-aquatic rodent native to Southern South America. In Argentina, it is an important fur resource for rural communities, and there is no evidence of its behaviour as a pest. Between October 2003 and February 2004, studies of habitat use at macro and micro scales were carried out on 6 ponds in a golf course, an artificial urban wetland free from hunting pressure and located within the coypu’s original distribution area. Coypus feed and build their burrows in the ponds but in the absence of hydrophilic vegetation, coypus sought food away from the ponds, covering distances up to 108 m and a feeding area as large as 19 m2. At the macrohabitat scale, the lower the herbaceous vegetation availability at the shore, the greater was the effective usage area. At the microhabitat level, coypus appeared to build their burrows in rather steep slopes (median = 75 cm) or high up on shores rising above the water level (mean = 61.2 cm) selecting ponds with mean values close to the aforementioned figures. The absence of hydrophilous vegetation, natural predators and human activity during the highest activity hours, in addition to suitable food resources around the year are considered to favour the coypu’s behaviour as a pest in these environments.     

Production and Evaluation of a Recombinant Chimeric Vaccine against Clostridium botulinum Neurotoxin Types C and D

Bovine botulism is a fatal disease that is caused by botulinum neurotoxins (BoNTs) produced by Clostridium botulinum serotypes C and D and that causes great economic losses, with nearly 100% lethality during outbreaks. It has also been considered a potential source of human food-borne illness in many countries. Vaccination has been reported to be the most effective way to control bovine botulism. However, the commercially available toxoid-based vaccines are difficult and hazardous to produce. Neutralizing antibodies targeted against the C-terminal fragment of the BoNT heavy chain (H_C) are known to confer efficient protection against lethal doses of BoNTs. In this study, a novel recombinant chimera, consisting of Escherichia coli heat-labile enterotoxin B subunit (LTB), a strong adjuvant of the humoral immune response, fused to the H_C of BoNT serotypes C and D, was produced in E. coli. Mice vaccinated with the chimera containing LTB and an equivalent molar ratio of the chimera without LTB plus aluminum hydroxide (Al(OH)₃) developed 2 IU/mL of antitoxins for both serotypes. Guinea pigs immunized with the recombinant chimera with LTB plus Al(OH)₃ developed a protective immune response against both BoNT/C (5 IU/mL) and BoNT/D (10 IU/mL), as determined by a mouse neutralization bioassay with pooled sera. The results achieved with guinea pig sera fulfilled the requirements of commercial vaccines for prevention of botulism, as determined by the Brazilian Ministry of Agriculture, Livestock and Food, Supply. The presence of LTB was essential for the development of a strong humoral immune response, as it acted in synergism with Al(OH)₃. Thus, the vaccine described in this study is a strong candidate for the control of botulism in cattle.     

Ultraviolet-B effects on photosystem II efficiency of natural phytoplankton communities from Antarctica

The impact of UVB on the Antarctic phytoplankton photosystem II repair cycle, involving the rapidly cycled D1 protein, was studied during summer 2002. On sunny and overcast days, phytoplankton (from 1-m depth) were exposed to natural light (+UVB) and Mylar-screened (–UVB) conditions. Half of the samples from each treatment were inoculated with lincomycin, an inhibitor of synthesis of chloroplast-encoded proteins including the D1 protein. Blocking D1 repair caused significant F_v/F_m depressions on sunny days but had not effect on the overcast day. Most of the F_v/F_m depression was caused by PAR and UVA with a non-significant contribution from UVB. In the presence of D1 repair, suppressing UVB had no effect on F_v/F_m when the samples originated from a weakly stratified water column with no defined upper mixed layer (UML) while it alleviated F_v/F_m depression when the phytoplankton samples originated from within an UML deeper than the depth of UVB penetration. These results suggest that UVB had more effect on the D1 repair process than on the damage process itself but that phytoplankton sensitivity to surface UVB exposure was influenced by their previous light history, partly determined by the vertical structure of the water column.     

Monoclonal gammopathy of undetermined significance and Russell body formation in Helicobacter pylori gastritis

BACKGROUND: Infection by Helicobacter pylori has been linked to monoclonal gammopathy of undetermined significance (MGUS). MGUS is thought to develop due to chronic antigenic stimulation in people with a specific genetic predisposition. METHODS AND RESULTS: We describe a patient presenting with dyspepsia associated with H. pylori-related erosive gastritis. Histopathologic findings revealed infiltration with plasma cells containing accumulated condensed intercisternal immunoglobulins, the so-called 'Russell bodies'. In addition, MGUS was present with total immunoglobulins within the normal range but a significantly decreased serum concentration of IgG subtype 3. Molecular analyses demonstrated IgH formation, T-cell receptor gamma rearrangement, and alterations within the IgHG3 gene sequence. Following H. pylori eradication, gastritis and dyspepsia gradually resolved but MGUS persisted for at least 22 months. CONCLUSIONS: This is the first report to demonstrate that upon infection with H. pylori, an impaired secretory capacity of plasma cells due to specific molecular changes can present as Russell body gastritis. The molecular findings question a pathogenetic link between Russell bodies and H. pylori, but suggest genetic alterations in the immunoglobulin locus as the possible cause for both MGUS and Russell body gastritis.     

Serpulids and other calcareous tube-dwelling encrusting polychaetes from the Early Cretaceous Agrio Formation (Neuquén Basin,Argentina)

Serpulids and other related tube-dwelling polychaetes are often ignored when found as fossil remains. They are, however, a widespread and important group today, and abundant literature has been published on them. Knowledge of fossil serpulids is centered on European material, and little has already been done on South American fossil calcareous tubes. In this paper, seven serpulid and sabellid morphotypes are described from the Early Cretaceous marine Agrio Formation of Argentina, revealing a diversity of worms recorded as encrusters on bivalves, ammonites and corals. Sabellids are represented by Glomerula cf. serpentina. Serpulids are represented by two subfamilies: “Serpulinae” includes Mucroserpula mucroserpula, Parsimonia antiquata, Placostegus cf. conchophilus, Propomatoceros semicostatus and P. sulcicarinatus; Spirorbinae is represented by heavily worn tiny coiled tubes assigned to ?Neomicrorbis. Serpulids and sabellids are one of the main components of the mollusk-encrusting fauna recorded in the Agrio Formation, along with small oysters but much more diverse. They are most commonly found as post-mortem encrusters, but some cases of unquestionable living interaction are also found, such as serpulid tubes embedded on coral branches. They are often overgrown by bryozoans, and sometimes by oysters; they frequently occur aggregated.     

The parasitoid Gonatopus bartletti reduces presence of plant-pathogenic Spiroplasma kunkelii within the leafhopper vector Dalbulus maidis

Homopteran vectors (e.g., leafhoppers) of plant pathogens are vessels for reproduction of cell wall‐free bacteria. These vectors also serve as hosts for larval parasitoid dipterans, hymenopterans, and strepsipterans. However, no study has explored the relationship among these wall‐free bacteria and parasitoid larvae within the insect host. We studied the corn stunt spiroplasma (CSS), Spiroplasma kunkelii Whitcomb (Mycoplasmatales: Spiroplasmataceae), a bacterium that originated from secondary symbionts that cause corn stunt disease in maize, Zea mays L., and its reproduction in the haemolymph of the corn leafhopper, Dalbulus maidis (Delong and Wolcott) (Homoptera: Cicadellidae). We also studied the dryinid parasitoid Gonatopus bartletti Olmi (Hymenoptera: Dryinidae), the larva of which feeds in the corn leafhopper haemolymph. Our results showed that when CSS and the wasp coexisted in D. maidis, the development of the parasitoid was not affected by S. kunkelii. Parasitoid development was successfully completed when leafhoppers acquired S. kunkelii before or after parasitism and when CSS had median (10 days) and long (20 days) incubation periods in the leafhopper before parasitization. The presence of S. kunkelii did not affect parasitoid development to the adult stage. However, polymerase chain reaction showed that the presence (survival) of S. kunkelii in the leafhopper was negatively affected by the parasitoid larva. Fewer leafhoppers had CSS before and after parasitization compared with leafhoppers that only acquired the CSS. This negative effect helps to explain the high parasitism rate by G. bartletti in D. maidis and the low presence of S. kunkelii in the corn leafhopper when CSS and the wasp parasitoid overlap throughout their geographic distribution. The parasitoid larva may negatively affect S. kunkelii by (1) producing antibacterial peptides that are toxic to CSS; (2) producing teratocytes that take nutrients from the host for larval development, but these nutrients are required by CSS; (3) affecting, indirectly, CSS through other symbiotic microorganisms; and (4) producing proteins with antibacterial activity that are present in the venom of the wasp parasitoid.     

Cellular and molecular effects of silymarin on the transdifferentiation processes of LX-2 cells and its connection with lipid metabolism

Molecular and Cellular Biochemistry - This study evaluated the cardioprotective effects of a miR-1275 mimic in a rat model of myocardial ischemia–reperfusion (I/R)-induced myocardial injury...     

Seasonality of recruitment and reproduction of Acanthocephalus tumescens (Acanthocephala) in fishes from Lake Moreno (Patagonia, Argentina)

The seasonality of recruitment and reproduction of Acanthocephalus tumescens at the component population level was investigated in Lake Moreno (Patagonia, Argentina). Seasonal samples of the principal fish host species were taken between spring 1999 and spring 2000. Prevalence, mean intensity, coefficient of dispersion, sex ratio, proportion of maturity stages of females, and percentages of the 2 sources of infection in the stomach of fishes were calculated. Overall prevalence, mean intensity, and coefficient of dispersion showed the same pattern of seasonal changes. The seasonal feeding patterns of fishes affect the occurrence of A. tumescens, producing 1 peak in spring and the other peak in autumn. The lower temperature in winter delay reproductive processes after the autumn period of recruitment.     

Aedes aegypti alkaline phosphatase ALP1 is a functional receptor of Bacillus thuringiensis Cry4Ba and Cry11Aa toxins

Bacillus thuringiensis subs. israelensis produces at least three Cry toxins (Cry4Aa, Cry4Ba, and Cry11Aa) that are active against Aedes aegypti larvae. Previous work characterized a GPI-anchored alkaline phosphatase (ALP1) as a Cry11Aa binding molecule from the gut of A. aegypti larvae. We show here that Cry4Ba binds ALP1, and that the binding and toxicity of Cry4Ba mutants located in loop 2 of domain II is correlated. Also, we analyzed the contribution of ALP1 toward the toxicity of Cry4Ba and Cry11Aa toxins by silencing the expression of this protein though RNAi. Efficient silencing of ALP1 was demonstrated by real-time quantitative PCR (qPCR) and Western blot. ALP1 silenced larvae showed tolerance to both Cry4Ba and Cry11Aa although the silenced larvae were more tolerant to Cry11Aa in comparison to Cry4Ba. Our results demonstrate that ALP1 is a functional receptor that plays an important role in the toxicity of the Cry4Ba and Cry11Aa proteins.