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1.
Summary Color notations of dorsal pelage were analyzed in 451 adult subterranean mole rats, comprising 19 populations and 4 chromosomal species (2n=52, 54, 58 and 60) of the Spalax ehrenbergi superspecies in Israel. In addition, the color notations of soil samples from the collection sites were measured. In an attempt to evaluate the degree of correlation between pelage color of mole rats and the local soil color, each color was compared both macro- and microgeographically. The macrogeographic comparisons were among populations of the 4 chromosomal species, and the microgeographic comparisons were among pairs of geographically neighboring subpopulations which occur under similar climatic conditions but differ in soil type and color. The results indicate that 1. no differences in pelage color notation exist between the sexes; 2. pelage of mole rats is generally characterized by an over-all grayish color, but its shades vary regionally and locally in accordance with varying soil color; 3. a positive correlation was found between pelage and local soil colors in the macrogeographic analysis and this correlation was verified in a microgeographic comparison; 4. specimens from populations of the northern chromosomal species (2n=52, 54) mainly inhabit terra rossa and basalt soils, respectively, with reddish brown tones, and they tend to have a more reddish shade, whereas animals from the central species (2n=58), which inhabits mainly dark soils including alluvial clays, terra rossa and brown rendzina and the souther species 2n=60, which occurs mainly in light soil types such as pale rendzina, sandy loams and loess, tend to have a more yellowish shade. The general appearance of specimens from 2n=58 was dark gray while that of 2n=60 specimens was light gray; 5. mole rats living in xeric environments (particularly 2n=60, but also 2n=54) are lighter than those which live in mesic environments (2n=52, 58). The results support the conclusion that pelage color of strictly subterranean mole rats is subject to selection pressures of overground predation of disharmonious types with their background soil color. The possibility that the pelage color variation and patterns also contributes to better thermoregulation while mole rats are above ground is discussed. 相似文献
2.
Shoshana Klein Drora Zenvirth Vardit Dror Arnold B. Barton David B. Kaback Giora Simchen 《Chromosoma》1996,105(5):276-284
The preferred positions for meiotic double-strand breakage were mapped on Saccharomyces cerevisiae chromosomes I and VI, and on a number of yeast artificial chromosomes carrying human DNA inserts. Each chromosome had strong
and weak double-strand break (DSB) sites. On average one DSB-prone region was detected by pulsed-field gel electrophoresis
per 25 kb of DNA, but each chromosome had a unique distribution of DSB sites. There were no preferred meiotic DSB sites near
the telomeres. DSB-prone regions were associated with all of the known ”hot spots” for meiotic recombination on chromosomes
I, III and VI.
Received: 19 March 1996; in revised form: 26 July 1996 / Accepted: 18 August 1996 相似文献
3.
Alfonso Represa Jrme Niquet Hlne Pollard Yehezkel Ben-Ari 《Developmental neurobiology》1995,26(3):413-425
Seizures set in motion complex molecular and morphological changes in vulnerable structures, such as the hippocampal complex. A number of these changes are responsible for neuronal death of CA3 and hilar cells, which involves necrotic and apoptotic mechanisms. In surviving dentate granule cells seizures induce an increased expression of tubulin subunits and microtubule-associated proteins, suggesting that an overproduction of tubulin polymers would lead to a remodeling of mossy fibers (the axons of granule cells). In fact, these fibers sprout in the dentate gyrus to innervate granule cell dendrites, creating recurrent excitatory circuits. In contrast, terminal mossy fibers do not sprout in the CA3 field. Navigation of mossy fiber's growth cones may be facilitated by astrocytes, which would exert differential effects by producing and excreting cell adhesion and substrate molecules. In the light of the results discussed here, we suggest that in adult brain activated-resident astrocytes (nonproliferating, tenascin-negative, neuronal cell-adhesion molecule-positive astrocytes) could contribute to the process of axonal outgrowth and synaptogenesis in the dentate gyrus, while proliferating astrocytes, tenascin-positive, could impede any axonal rearrangement in CA3. © 1995 John Wiley & Sons, Inc. 相似文献
4.
Elon Pras Nina Raben Eliahu Golomb Nadir Arber Ivona Aksentijevich Jonathan M. Schapiro Daniela Harel Giora Katz Uri Liberman Mordechai Pras Daniel L. Kastner 《American journal of human genetics》1995,56(6):1297-1303
Cystinuria is an autosomal recessive disease characterized by the development of kidney stones. Guided by the identification of the SLC3A1 amino acid–transport gene on chromosome 2, we recently established genetic linkage of cystinuria to chromosome 2p in 17 families, without evidence for locus heterogeneity. Other authors have independently identified missense mutations in SLC3A1 in cystinuria patients. In this report we describe four additional cystinuria-associated mutations in this gene: a frameshift, a deletion, a transversion inducing a critical amino acid change, and a nonsense mutation. The latter stop codon was found in all of eight Ashkenazi Jewish carrier chromosomes examined. This report brings the number of disease-associated mutations in this gene to 10. We also assess the frequency of these mutations in our 17 cystinuria families. 相似文献
5.
6.
A supposed sporulation-deficient mutation of Saccharomyces cerevisiae is found to affect mating in haploids and in diploids, and to be inseparable from the mating-type locus by recombination. The mutation is regarded as a defective a allele and is designated a*. This is confirmed by its dominance relations in diploids, triploids, and tetraploids. Tetrad analysis of tetraploids and of their sporulating diploid progeny suggests the existence of an additional locus, RME, which regulates sporulation in yeast strains that can mate. Thus the recessive homozygous constitution rme/rme enables the diploids a*/α, a/a*, and α/α to go through meiosis. Haploids carrying rme show apparent premeiotic DNA replication in sporulation conditions. This new regulatory locus is linked to the centromere of the mating-type chromosome, and its two alleles, rme and RME, are found among standard laboratory strains. 相似文献
7.
Zaid A. Abassi Marina Okun-Gurevich Niroz Abu Salah Hoda Awad Yossi Mandel Gadi Campino Ahmad Mahajna Giora Z. Feuerstein Mike Fitzpatrick Aaron Hoffman Joseph Winaver 《PloS one》2013,8(11)
Uncontrolled hemorrhage, resulting from traumatic injuries, continues to be the leading cause of death in civilian and military environments. Hemorrhagic deaths usually occur within the first 6 hours of admission to hospital; therefore, early prehospital identification of patients who are at risk for developing shock may improve survival. The aims of the current study were: 1. To establish and characterize a unique model of uncontrolled internal hemorrhage induced by massive renal injury (MRI), of different degrees (20-35% unilateral nephrectomy) in rats, 2. To identify early biomarkers those best predict the outcome of severe internal hemorrhage. For this purpose, male Sprague Dawley rats were anesthetized and cannulas were inserted into the trachea and carotid artery. After abdominal laparotomy, the lower pole of the kidney was excised. During 120 minutes, hematocrit, pO2, pCO2, base excess, potassium, lactate and glucose were measured from blood samples, and mean arterial pressure (MAP) was measured through arterial tracing. After 120 minutes, blood loss was determined. Statistical prediction models of mortality and amount of blood loss were performed. In this model, the lowest blood loss and mortality rate were observed in the group with 20% nephrectomy. Escalation of the extent of nephrectomy to 25% and 30% significantly increased blood loss and mortality rate. Two phases of hemodynamic and biochemical response to MRI were noticed: the primary phase, occurring during the first 15 minutes after injury, and the secondary phase, beginning 30 minutes after the induction of bleeding. A Significant correlation between early blood loss and mean arterial pressure (MAP) decrements and survival were noted. Our data also indicate that prediction of outcome was attainable in the very early stages of blood loss, over the first 15 minutes after the injury, and that blood loss and MAP were the strongest predictors of mortality. 相似文献
8.
9.
Zenvirth D Richler C Bardhan A Baudat F Barzilai A Wahrman J Simchen G 《Chromosoma》2003,111(6):369-376
Meiotic recombination in yeast is initiated at DNA double-strand breaks (DSBs), processed into 3′ single-strand overhangs that are active in homology search, repair and formation of recombinant molecules. Are 3′ overhangs recombination intermediaries in mouse germ cells too? To answer this question we developed a novel approach based on the properties of the Klenow enzyme. We carried out two different, successive in situ Klenow enzyme-based reactions on sectioned preparations of testicular tubules. Signals showing 3′ overhangs were observed during wild-type mouse spermatogenesis, but not in Spo11 ?/? males, which lack meiotic DSBs. In Atm ?/? mice, abundant positively stained spermatocytes were present, indicating an accumulation of non-repaired DSBs, suggesting the involvement of ATM in repair of meiotic DSBs. Thus the processing of DSBs into 3′ overhangs is common to meiotic cells in mammals and yeast, and probably in all eukaryotes. 相似文献
10.
Presynaptic kainate receptors that enhance the release of GABA on CA1 hippocampal interneurons 总被引:9,自引:0,他引:9
We report that kainate receptors are present on presynaptic GABAergic terminals contacting interneurons and that their activation increases GABA release. Application of kainate increased the frequency of miniature inhibitory postsynaptic currents recorded in CA1 interneurons. Local applications of glutamate but not of AMPA or NMDA also increased GABA quantal release. Application of kainate as well as synaptically released glutamate reduced the number of failures of GABAergic neurotransmission between interneurons. Thus, activation of presynaptic kainate receptors increases the probability of GABA release at interneuron-interneuron synapses. Glutamate may selectively control the communication between interneurons by increasing their mutual inhibition. 相似文献