Sex chromosomes pairing in two Arvicolidae species: Microtus nivalis and Arvicola sapidus

Arvicolid rodents present both synaptic and asynaptic sex chromosomes. We analyzed the pairing behaviour of sex chromosomes in two species belonging to this rodent group (Microtus nivalis and Arvicola sapidus). At pachynema, the sex chromosomes of both species paired in a small region while the rest remain unsynapsed. Consequently at metaphase I, sex chromosomes present end-to-end association. Thus, the pairing behaviour of sex chromosomes in these species is very similar to that previously described for other arvicolid rodents and for most mammals. According to this, we propose that synaptic sex chromosomes were the ancestral condition in the family Arvicolidae, including the genus Microtus. The phylogenetic origin of the asynaptic sex chromosomes in the genus Microtus would have arisen once in the lineage that originated the species M. arvalis/agrestis and related species, while the lineage that originated the species M. oeconomous and related species conserved synaptic chromosomes. Furthermore, the phylogenetic relationships between the genus Microtus, Chionomys and Pitymys are discussed in relation to the synaptic behaviour of sex chromosomes.     

The novel serine protease PreR-Co promotes endothelium-independent vasorelaxation in rabbit aortic rings

The effect of a novel enzyme (PreR-Co) that activates renal prorenin was studied on rabbit aortas with and without endothelium. It was tested 1) in the basal tone of nonstimulated or ANG II-sensitized rings or rings precontracted with norepinephrine (NE), PGF(2alpha), high KCl concentration, and 2) in rings pretreated with enalaprilat, losartan, PD-123319, N(omega)-nitro-l-arginine methyl ester, HOE-140, indomethacin, or serine protease inhibitors (PMSF, aprotinin, or soybean trypsin inhibitor); kallilkrein and bradykinin were also tested in ANG II-sensitized rings. PreR-Co produced a vasorelaxant effect in the basal tone and in the precontracted rabbit aorta. The effect was endothelium independent, potentiated by endothelium removal or nitric oxide (NO) synthase inhibition, and abolished by boiling the enzyme. In addition, the effect improved when basal tone was increased in ANG II-sensitized aortic rings or in precontracted vessels. No activation of the ANG II, bradykinin, prostaglandin, or NO pathway mediating the PreR-Co response could be obtained, suggesting a direct action of the enzyme. This action seems to be dependent on esterasic activity because serine protease inhibitors like PMSF and aprotinin were able to block the vasorelaxant effect of PreR-Co.     

Heat requirement for the onset of the Olea europaea L. pollen season in several sites in Andalusia and the effect of the expected future climate change

Olives are one of the largest crops in the Mediterranean region, especially in Andalusia, in southern Spain. A thermal model has been developed for forecasting the start of the olive tree pollen season at five localities in Andalusia: Cordoba, Priego, Jaen, Granada and Malaga using airborne pollen and meteorological data from 1982 to 2001. Threshold temperatures varied between 5°C and 12.5°C depending on bio-geographical characteristics. The external validity of the results was tested using the data for the year 2002 as an independent variable and it confirmed the models accuracy with only a few days difference from predicted values. All the localities had increasingly earlier start dates during the study period. This could confirm that olive flower phenology can be considered as a sensitive indicator of the effects of climate fluctuations in the Mediterranean area. The theoretical impact of the predicted climatic warming on the olives flowering phenology at the end of the century is also proposed by applying Regional Climate Model data. A general advance, from 1 to 3 weeks could be expected, although this advance will be more pronounced in mid-altitude inland areas.     

Intracerebroventricular physostigmine enhances blood pressure and heat loss in running rats.

The aim of this study was to evaluate the effects of the stimulation of central cholinergic synapses in the regulation of heat loss in untrained rats during exercise. The animals were separated into two groups (exercise or rest) and tail skin temperature (T(tail)), core temperature and blood pressure were measured after injection of 2 microL of 5x10(-3) M physostigmine (Phy; n = 8) or 0.15 M NaCl solution (Sal; n = 8) into the lateral cerebral ventricle. Blood pressure was recorded by a catheter implanted into the abdominal aorta, T(tail) was measured using a thermistor taped to the tail and intraperitoneal temperature (T(b)) was recorded by telemetry. During exercise, Phy-treated rats had a higher increase in mean blood pressure (147 +/- 4 mmHg Phy vs. 121 +/- 3 mmHg Sal; P < 0.001) and higher T(tail) (26.4 +/- 1.0 degrees C Phy vs. 23.8 +/- 0.5 degrees C Sal; P < 0.05) that was closely related to the increase in systolic arterial pressure (r = 0.83; P < 0.001). In addition, Phy injection attenuated the exercise-induced increase in T(b) compared with controls without affecting running time. We conclude that the activation of central cholinergic synapses during exercise increases heat dissipation due to the higher increase in blood pressure.     

Evaluation of the Content of Antimony,Arsenic, Bismuth,Selenium, Tellurium and Their Inorganic Forms in Commercially Baby Foods

The purpose of the investigation is to reveal the influence of dietary calcium on fluorosis-induced brain cell apoptosis in rat offspring, as well as the underlying molecular mechanism. Sprague–Dawley (SD) female rats were randomly divided into five groups: control group, fluoride group, low calcium, low calcium fluoride group, and high calcium fluoride group. SD male rats were used for breeding only. After 3 months, male and female rats were mated in a 1:1 ratio. Subsequently, 18-day-old gestation rats and 14- and 28-day-old rats were used as experimental subjects. We determined the blood/urine fluoride, the blood/urine calcium, the apoptosis in the hippocampus, and the expression levels of apoptosis-related genes, namely Bcl-2, caspase 12, and JNK. Blood or blood/urine fluoride levels and apoptotic cells were found significantly increased in fluorosis rat offspring as compared to controls. Furthermore, the Bcl-2 messenger RNA (mRNA) expression levels significantly decreased, and caspase 12 mRNA levels significantly increased in each age group as compared to controls. Compared with the fluoride group, the blood/urine fluoride content and apoptotic cells evidently decreased in the high calcium fluoride group, Bcl-2 mRNA expression significantly increased and caspase 12 mRNA expression significantly decreased in each age group. All results showed no gender difference. Based on these results, the molecular mechanisms of fluorosis-induced brain cell apoptosis in rat offspring may include the decrease in Bcl-2 mRNA expression level and increase in caspase 12 mRNA expression signaling pathways. High calcium intake could reverse these gene expression trends. By contrast, low calcium intake intensified the toxic effects of fluoride on brain cells.     

Study of seasonal and daily variations in airborneOlea europaea L. pollen in Jaén (Spain), 1993–1995

A study is made of the seasonal and daily variations in the concentrations of pollen ofOlea europaea L. over three consecutive years (1993–1995) in the atmosphere of Jaén (southern Spain). A Burkard volumetric spore trap was used for sampling. The results show that the highest concentrations of airborne olive pollen occur during May and the first 2 weeks of June, when levels often exceed 500 grains/m³ and occasionally reach nearly 5000 grains/m³ (the levels of allergenic pollen in the atmosphere of Jaén are among the highest in Europe). Over the 3-year study period a significant seasonal variation was detected, not only in the development of the principal pollination period, but also in the value of the maximum pollen concentrations recorded.     

Synaptonemal complex analysis of spermatocytes of Talpa occidentalis (Insectivora, Mammalia): autosomal synapsis and substaging of zygonema and pachynema

Spermatocytes from the mole, Talpa occidentalis, a species that includes both XX males and intersexes, were surface-spread and silver-stained to substage meiotic prophase from early zygonema through pachynema. In zygonema, only the Z2 and Z3 substages were found. This stage differed in comparison with such species as the Chinese hamster, laboratory mouse, and deer mouse, which belong to orders other than Insectivora. Pachynema, in which five substages were established (P1-P5), seems to be a more homogeneous stage, and remarkable differences with respect to the above-mentioned species were not found. Synaptic adjustment was demonstrated in X-Y pairing. Nonhomologous pairing was evident at the Y-centromeric region and considered likely in the proximal arm of this chromosome. In addition to sequencing the events taking place during zygonema and pachynema in males from a wild population in which some members show sex reversal, our finding represents the first attempt to substage zygonema and pachynema in an Insectivore species, thus contributing to current knowledge of the nature and degree of variability in the mammalian synaptic process.