Individual Odours in Two Chromosomal Species of Blind,Subterranean Mole Rat (Spalax ehrenbergi): Conspecific and Cross-species Discrimination

Mole rats from two chromosomal species (2n = 58 and 2n = 60) of the Spalax ehrenbergi superspecies of Israel were tested to determine whether they were able to discriminate differences in the odour of urine from same-sex individuals of their own and of the other chromosomal species. An habituation-discrimination apparatus was designed for use with these solitary and blind subterranean rodents. Animals habituated to the odour of urine from one individual presented for 10 min at a centre sniffing area in the roof of a 50 cm long Perspex tunnel. The odour of urine from the original donor and from a second individual were presented at two other sniffing areas in the tunnel roof during a 5 min discrimination phase. Significant differences in the time spent investigating the two odours demonstrated successful discrimination between them. The results indicate that male and female mole rats of both species can discriminate between the individual-specific odour cues in urine from pairs of conspecifics and pairs of heterospecific mole rats.     

Adaptive differentiation of body size in speciating mole rats

Summary We report the body weight of 1,653 subterranean mole rats comprising 12 populations and 4 chromosomal species (2n=52, 54, 58 and 60) of the Spalax ehrenbergi superspecies in Israel. The sample was collected from 1970 to 1985 and includes all captured animals with a minimal age of 10 months. The results indicated the following. (a) Body weight of males was significantly higher than that of females. (b) There is a southward latitudinal gradient in body size. Northern animals living in cooler and more productive mesic environments are larger than southern animals living in warmer and less productive xeric environments. (c) The interspecific differences for each sex are statistically significant. (d) Body size is negatively correlated with temperature variables, and positively correlated with plant cover (reflecting productivity or food resources) and rainy days. (e) The best predictors of body size, explaining up to 87% of the variation in size included various combinations of temperature variables and plant cover.We conclude that in both adaptation and speciation natural selection is a major agent of differentiation of body size in accordance with multiple factors, primarily temperature and food resources operating on the energetics balance.     

Reproduction and Feeding of the Electric Fish Brachyhypopomus gauderio (Gymnotiformes: Hypopomidae) and the Discussion of a Life History Pattern for Gymnotiforms from High Latitudes

The reproductive biology and feeding habits of the electric fish Brachyhypopomus gauderio were studied. The species has seasonal reproductive behavior, with breeding occurring during the Southern Hemisphere spring and summer, and having a positive relation with the photoperiod variation. Brachyhypopomus gauderio was defined as a fractional spawner, with low relative fecundity and high first maturation size. Sexual dimorphism was registered, males undergoing hypertrophy of the distal portion of caudal filament. The results on reproductive biology herein obtained are in agreement with data concerning gymnotiforms from Southern Brazil and Uruguay, pointing to an ecological pattern for the species from high latitudes, differing from species with tropical distribution. According to the analysis of the food items, B. gauderio feed mainly on autochthonous insects, likewise the other gymnotiforms previously investigated, leading to conclude that there is no variation on the diet of the species of the order related to climatic conditions or even to habitat of occurrence.     

Osteopontin-Stimulated Vascular Smooth Muscle Cell Migration Is Mediated by β3 Integrin

Osteopontin (OPN), a 41-kDa phosphorylated glycoprotein, has been detected in rat aorta and carotid arteries, and expression of its mRNA in blood vessels is strongly increased in response to vascular injury. To investigate the potential role of OPN in vascular pathophysiology, we studied the effect of rat OPN on aortic smooth muscle cell migration and proliferation in vitro. OPN enhanced the migration of rat smooth muscle cells in a time- and concentration-dependent manner with an EC₅₀ value of 46 ± 11 nmol/liter (n = 5). The maximal increase in cell migration by OPN was 29-fold over basal levels. OPN-induced smooth muscle cell migration was inhibited in a concentration-dependent manner by the monoclonal antibody F11, which recognizes the rat integrin subunit β₃. In contrast, polyclonal antiserum recognizing the rat integrin β₁ subunit did not inhibit smooth muscle cell migration in response to OPN, but did block fibronectin-promoted migration. Moreover, OPN-induced smooth muscle cell migration was dependent on the presence of extracellular divalent cations and was significantly inhibited by anti-OPN antibodies. OPN did not stimulate [³H]thymidine incorporation into cultured smooth muscle cells, indicating that it selectively enhanced migration. In view of the pathological significance of arterial smooth muscle cell migration in the formation of intimal thickening, our results suggest that smooth muscle cell recognition of OPN, probably through the vitronectin receptor, α_vβ₃, could play a role in the cells' response to vascular injury and especially neointima formation.     

Dynorphins and leu-enkephalin in brain nuclei and pituitary of WKY and SHR rats

The distribution of dynorphin 1–13 (Dyn-1–13, Dyn-(1–8) and Leu⁵-enkephalin (LE) immunoreactivities (ir) were determined in discrete brain nuclei of normotensive (WKY) and hypertensive (SHR) rats. The concentration of ir-Dyn-(1–13) and ir-Dyn-(1–8) varied markedly among the various nuclei studies with a predominance of ir-Dyn-(1–13) over ir-Dyn-(1–8) in all the nuclei of both WKY and SHR rats. Ir-LE also showed large variations in different sites and no consistent relationships were found between the distribution of ir-Dyn-(1–8), Dyn-(1–13) and LE. SHR rats had lower levels of ir-Dyn-(1–13), Dyn-(1–8) and LE in the suprachiasmatic nucleus compared with WKY rats. In addition, SHR rats had lower levels of ir-Dyn-(1–8)- in the paraventricular and central amygdala, and higher ir-Dyn-(1–13) levels in the substantia nigra. The level of ir-Dyn-(1–13) in the neurointermediate lobe (NIL) of SHR rats was decreased substantially compared with that of WKY rats. The localization of these opioid peptides suggests that dynorphin-like peptides may serve a variety of hypothalamic and extrahypothalamic functions which might differ between SHR and WKY rats.     

Recall antigen delayed-type hypersensitivity skin testing: standardization of self-reading by patients

Summary In order to evaluate a self-reading system for the measurement of immunocompetence in cancer prognosis, a battery of delayed-type hypersensitivity skin tests with antigens including dermatophytin, candida, Varidase (streptokinase-streptodornase), mumps, and purified protein derivative (PPD) was administered to 50 cancer patients. The resulting erythema and induration were read by both technicians and patients at 24 and 48 h after placement of the tests. In addition, another group of 85 cancer patients received two identical candida skin tests placed at the same time on either the same or the opposite arm. The results from these two groups of patients indicated that patients' readings correlated well with technicians' readings, with most of the correlation coefficients being greater than 0.8. The weakest correlations were with antigens producing a large response. There was significant variability in the two identical simultaneously placed skin tests, and the correlation coefficients were much lower. The relevance of these data to serial skin testing is discussed.     

Commitment to meiosis: what determines the mode of division in budding yeast?

In budding yeast, commitment to meiosis is attained when meiotic cells cannot return to the mitotic cell cycle even if the triggering cue (nutrients deprivation) is withdrawn. Commitment is arrived at gradually, and different aspects of meiosis may be committed at different times. Cells become fully committed to meiosis at the end of Prophase I, long after DNA replication and just before the first meiotic division (M_I). Whole‐genome gene expression analysis has shown that committed cells have a distinct and rapid response to nutrients, and are not simply insulated from environmental signals. Thus becoming committed to meiosis is an active process. The cellular event most likely to be associated with commitment to meiosis is the separation of the duplicated spindle‐pole bodies (SPBs) and the formation of the spindle. Commitment to the mitotic cell cycle is also associated with the separation of SPBs, although it occurs in G1, before DNA replication.     

Lichen Colonization on Cobbles in the Negev Desert Following 15 Years in the Field

Rock slabs were placed from 1991 through 2006 at the bottom of a north- (NFS) and a south-facing (SFS) slope of a first order drainage basin in the Negev Desert Highlands, Israel (P = 95 mm) where natural cobbles have >95% cover of endolithic and epilithic lichens. Periodic measurements of rain, dew and chlorophyll content took place. Lichen cover and the regeneration time were aspect-dependent. Lichen cover was 98% and 61% at NFS and SFS, respectively, while the lichen's recovery time was respectively ～45 and ～80 years. The fast regeneration time may have important implications regarding weathering and soil formation.