Genetic structure of populations of Calomys laucha (muridae, sigmodontinae) from central Argentina

The genetic structure of populations of the Sigmodontinae rodent Calomys laucha was studied by means of allozyme electrophoresis. This highly opportunistic species is found preferably in periodically perturbed habitats of crop fields in central Argentina, where it can attain very high densities. A total of 17 enzymatic proteins assayed gave information on 25 loci; only four were monomorphic in the seven populations studied. Levels of genetic variability (H_o from 0.144 to 0.171; P_95% from 44% to 56%) were higher than mean values reported for mammals and rodents. These high levels of heterozygosity could be maintained by large populations that do not experience great fluctuations in size, or by a social structure consistent in many small breeding groups that are formed and dissappear every breeding season. Genetic differentiation at a macrogeographical scale (θ=0.018) was low but statistically significant, and showed no correlation with geographic distance between pairs of populations. The pattern of population differentiation found is compatible with a relatively recent range expansion.     

Diversity in soil fungi from undisturbed and disturbed Celtis tala and Scutia buxifolia forests in the eastern Buenos Aires province (Argentina)

The rhizospheric soil microfungi from a native forest (undisturbed and disturbed) were studied using soil dilution plate and soil washing methods. Fungi were isolated using slightly acid and alkaline culture media. 54 taxa were isolated: 49 from undisturbed forest soil and 37 from disturbed forest soil. Acremonium sp., Aspergillus ustus, Coemansia pectinata, Doratomyces stemonitis, Fusarium solani, F. oxysporum, Gliocladium roseum, Humicola fusco-atra, Mortierella sp., Penicillium lilacinum, Trichoderma harzianum, and T. koningii, showed the highest frequency, in both, undisturbed and disturbed forests. In undisturbed soil forest the biodiversity index was 3.97 whereas in disturbed ones was 3.89.     

Gastric mucosal endogenous prostacyclin levels are different in Brattleboro rats compared with Wistar strain

Homozygous Brattleboro rats were investigated and compared to normal (physiological) Wistar strain rats regarding their gastric mucosal endogenous prostacyclin (PG-I(2)) level. It seems that the Brattleboro animals have a significantly lower level of this important protective material. Wistar rats having an artificial pituitary stalk lesion (which is the artificial equivalent of homozygous Brattleboro animals) showed no differences in endogenous mucosal prostacyclin level compared to normal Wistar rats. Therefore, we concluded that this hitherto unknown property of the homozygous Brattleboro rats is genetically determined.     

Fluorescent competitive flow-through assay for chloramphenicol using molecularly imprinted polymers

It is a fact that molecular imprinting techniques have reached tremendous importance in the research of new artificial recognition systems. These methods resemble the mechanism of natural recognition, generally based on non-covalent interactions, but improving their stability by means of a simple and inexpensive technique. Molecular imprinting polymers (MIPs) are easily obtained by copolymerisation of suitable functional monomers and crosslinkers in the presence of the print molecule. Removal of the template leaves a polymer that selectively recognises it. In this work, different imprinted polymers for chloramphenicol (CAP) obtained using different monomers and polymerisation conditions were tested in a HPLC system, in order to obtain a highly selective material for CAP. The optimised MIP was then used as recognition phase in a fluorescent competitive flow assay to determine chloramphenicol.     

Extracellular lipolytic activity in Phoma glomerata

Several properties of the lipolytic activity exhibited by the conidial fungus Phoma glomerata were studied. Lipolytic activity in an aqueous buffer medium was measured on triacylglycerol, phosphoglyceride and cholesterol ester under different experimental conditions. The effect of storage temperature on the stability of the hydrolytic activity, and optimal conditions of temperature and time of maximal activity were determined. The optimal conditions for maximal lipolytic activity were found to be 40–50 °C and 1 h. The activity released to the medium by 1 mg cells for 1 h at 40 °C was stated as the enzyme released unit (ERU). The protein fraction of MW > 50 kDa obtained by ultrafiltration of the medium, was active on the three substrates assayed, and it showed a non-specific hydrolytic activity on both the 1- and 2-acyl esters either in the neutral glyceride or in the phosphoglyceride. A protein of M _r approx. 75 kDa was the only one that showed esterase activity. The crude medium, stored at –15 °C, maintained its initial hydrolytic activity on triacylglycerol for at least 42 days, though when it was kept for 10 days at 4 °C, the activity fell to 50%. Kinetic parameters using substrates such as triolein (TO), dipalmitoyl phosphatidylcholine (DPPC) and cholesteryl oleate (ChoO), were comparatively evaluated. The activity of the enzyme in the hydrolysis of TO showed the highest values, whereas the maximal specific activities were less when the enzyme was assayed against DPPC and ChoO.     

18F-EF5 PET Is Predictive of Response to Fractionated Radiotherapy in Preclinical Tumor Models

We evaluated the relationship between pre-treatment positron emission tomography (PET) using the hypoxic tracer ¹⁸F-[2-(2-nitro-1-H-imidazol-1-yl)-N-(2,2,3,3,3- pentafluoropropyl) acetamide] (¹⁸F-EF5) and the response of preclinical tumor models to a range of fractionated radiotherapies. Subcutaneous HT29, A549 and RKO tumors grown in nude mice were imaged using ¹⁸F-EF5 positron emission tomography (PET) in order to characterize the extent and heterogeneity of hypoxia in these systems. Based on these results, 80 A549 tumors were subsequently grown and imaged using ¹⁸F-EF5 PET, and then treated with one, two, or four fraction radiation treatments to a total dose of 10–40 Gy. Response was monitored by serial caliper measurements of tumor volume. Longitudinal post-treatment ¹⁸F-EF5 PET imaging was performed on a subset of tumors. Terminal histologic analysis was performed to validate ¹⁸F-EF5 PET measures of hypoxia. EF5-positive tumors responded more poorly to low dose single fraction irradiation relative to EF5-negative tumors, however both groups responded similarly to larger single fraction doses. Irradiated tumors exhibited reduced ¹⁸F-EF5 uptake one month after treatment compared to control tumors. These findings indicate that pre- treatment ¹⁸F-EF5 PET can predict the response of tumors to single fraction radiation treatment. However, increasing the number of fractions delivered abrogates the difference in response between tumors with high and low EF5 uptake pre-treatment, in agreement with traditional radiobiology.     

Study of the antidiabetic capacity of the VO(dmpp)2 complex

In this work we report biochemical ex vivo studies with a vanadium compound containing a pyridinone ligand, the bis(1,2-dimethyl-3-hydroxy-4-pyridinonate)oxovanadium (IV), V^IVO(dmpp)₂, which has shown to have promising antidiabetic activity. The experiments were carried out on primary adipocytes of 6-8 week old Wistar rats. Insulin-stimulated glucose uptake studies were performed using a radioactive assay by measuring the (U)-¹⁴C-glucose taken up by the isolated adipocytes for 30 min. Adipocytes were incubated with and without insulin and in the presence and absence of different concentrations of V^IVO(dmpp)₂ (100-500 μM) for 45 min. We observed that in a nontoxic concentration, as demonstrated by the Alamar Blue test, V^IVO(dmpp)₂ significantly increases glucose uptake, in the absence of insulin, by 5-folds higher than basal, and it has a significant inhibitory effect of 78% on free fatty acid release in isolated adipocytes from normal rats. We also demonstrated that it promotes the phosphorylation of Akt1, a key protein in the insulin signaling cascade. These results were compared with those obtained with another vanadium compound reported in the literature, with a similar structure, the bis(maltolato)oxovanadium (IV) (BMOV), which is now in clinical trials. Our ex vivo results clearly indicate that V^IVO(dmpp)₂ is a good candidate to be a promising drug for the treatment of diabetes and other metabolic disorders.     

The effects of temperature and salinity on vital biological functions of the Antarctic crustacean Serolis polita

Effects of temperature rise (from 0 to +5°C) and salinity decline (from 34 to 30 psu) on vital biological functions of the Antarctic isopod Serolis polita were studied in laboratory experiments. Behavioural reactions to food odour, as well as righting responses and reburying in the sediments, were measured. Both temperature increase and salinity decline impaired the ability of S. polita to perform these biological functions critical for their long-term survival, by lowering the number of isopods able to right and rebury in the sediment, increasing time-to-right, reducing locomotory activity and weakening isopod reaction to food odour. Significant interactive effects between temperature and salinity on time-to-right and time spent swimming were observed, with isopods being more vulnerable to lower salinities when exposed to higher temperatures. Some biological functions (righting, reburying) were more sensitive to temperature and salinity changes than others (swimming). In conclusion, our findings strongly suggest that Antarctic isopods are vulnerable to environmental changes, and their ability to cope with them is limited.     

Second Language as an Exemptor from Sociocultural Norms. Emotion-Related Language Choice Revisited

Bilinguals often switch languages depending on what they are saying. According to the Emotion-Related Language Choice theory, they find their second language an easier medium of conveying content which evokes strong emotions. The first language carries too much emotional power, which can be threatening for the speaker. In a covert experiment, bilingual Polish students translated texts brimming with expletives from Polish into English and vice versa. In the Polish translations, the swear word equivalents used were weaker than in the source text; in the English translations, they were stronger than in the original. These results corroborate the ERLC theory. However, the effect was only observed for ethnophaulisms, i.e. expletives directed at social groups. It turns out that the main factor triggering the language choice in bilinguals is not necessarily the different emotional power of both languages, but social and cultural norms.     

β-N-Acetylhexosaminidase involvement in α-conglutin mobilization in Lupinus albus

Glycosylation is an important post-translational modification involved in the modulation of a wide variety of cellular processes. Because glycosydases are central, the aim of this study was to investigate the glycosyl activity present in the cotyledons of the seeds of an important crop legume, Lupinus albus, as well as potential natural substrates of the detected enzymes.