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71.
Summary The vascular architecture of the rat testis and spermatic cord was studied by a corrosion cast technique combined with scanning and transmission electron microscopy, and light microscopy. The casts preserve the endothelial impressions of the vessels and enable them to be differentiated into the various vascular components. Frequent arterio-arterial anastomotic arcades and occasional arterio-venous anastomotic channels are seen. A well defined hexagonal pattern of intertubular and peritubular vessels surround the seminiferous tubules. Prominent large endothelial nuclei protrude into the arterial lumina at branching sites, but their functional significance is not known. The outermost vascular layer of the testis consists of large veins, venules, and capillaries, but lacks any arterial branches; it also contains loosely arranged veno-venous anastomotic networks. We have named this vascular layer the sub-albugineal venous plexus. The testicular artery increases in luminal diameter as it approaches the testis. The periarterial capillary plexus, which lies between the pampiniform plexus and the testicular artery, is drained by two types of venules. 相似文献
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The effects of delta 9-tetrahydrocannabinol (THC) treatment on acid soluble pools of uridine nucleoside and nucleotides were investigated in Tetrahymena pyriformis and in isolated mouse lymphocytes and spermatogenic cells. In THC treated Tetrahymena and mouse lymphocytes the uptake of labelled precursor into acid soluble pools of uridine nucleoside and nucleotides fluctuated, whereas in pachytene spermatocytes and round spermatid cells the labelled pool was reduced. The reduction in the labelled pool measured in mouse spermatogenic cells was attributed primarily to a reduction in radioactively labelled uridine nucleoside. Treatment of Tetrahymena in high concentrations of THC (960 and 3,200 microM) resulted in an increase of labelled uridine nucleoside and a reduction in the amount of labelled uridine nucleotides. Expansion of the acid soluble pool with radioactive uridine resulted in small differences in labelled nucleoside and nucleotides in control and THC treated Tetrahymena and mouse lymphocytes. The results are discussed in terms of the effects of THC on macromolecular synthesis in various cellular systems. 相似文献
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Vincent Ranwez Frédéric Delsuc Sylvie Ranwez Khalid Belkhir Marie-Ka Tilak Emmanuel JP Douzery 《BMC evolutionary biology》2007,7(1):241
Background
Molecular sequence data have become the standard in modern day phylogenetics. In particular, several long-standing questions of mammalian evolutionary history have been recently resolved thanks to the use of molecular characters. Yet, most studies have focused on only a handful of standard markers. The availability of an ever increasing number of whole genome sequences is a golden mine for modern systematics. Genomic data now provide the opportunity to select new markers that are potentially relevant for further resolving branches of the mammalian phylogenetic tree at various taxonomic levels. 相似文献75.
Tilak Kumar Gupta Sven Klumpe Karin Gries Steffen Heinz Wojciech Wietrzynski Norikazu Ohnishi Justus Niemeyer Benjamin Spaniol Miroslava Schaffer Anna Rast Matthias Ostermeier Mike Strauss Jürgen M. Plitzko Wolfgang Baumeister Till Rudack Wataru Sakamoto Jörg Nickelsen Jan M. Schuller Benjamin D. Engel 《Cell》2021,184(14):3643-3659.e23
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Shallu Thakur Pankaj K. Singh Rajeev Rathour Mukund Variar Sangam K. Prashanthi S. Gopalakrishnan A. K. Singh U. D. Singh Duni Chand Nagendra K. Singh Tilak R. Sharma 《Molecular breeding : new strategies in plant improvement》2014,34(3):1449-1463
Development and large-scale genotyping of single-nucleotide polymorphism (SNP) is required to use identified sequence variation in the alleles of different genes to determine their functional relevance to the candidate gene(s). In the present study, Illumina GoldenGate assay was used to validate and genotype SNPs in a set of six major rice blast resistance genes, viz. Pi-ta, Piz(t), Pi54, Pi9, Pi5(1) and Pib, distributed over five chromosomes, to understand their functional relevance and study the population structure in rice. All the selected SNPs loci (96) of six blast (Magnaporthe oryzae) resistance genes were genotyped successfully in 92 rice lines with an overall genotype call rate of 92.0 % and minimum GenTrain cutoff score of ≥0.448. The highest genotyped SNPs were found in japonica type (97.1 %) rice lines, followed by indica (92.12 %), indica basmati (91.84 %) and minimum in case of wild species (82.0 %). Among the genotyped loci, the highest score (98.68 %) was observed in case of Piz(t), followed by Pi-ta, Pi5(1), Pib, Pi54 and Pi9. Polymorphism was obtained in 87.5 % SNPs loci producing 7,728 genotype calls. Minor allele frequency ranged from 0.01 to 0.49 and has good differentiating power for distinguishing different rice accessions. Population structure analysis revealed that a set of genotypes from four rice subpopulations had “admix” ancestry (>26 %) with more than one genetic background of indica, japonica and wild types. SNPs markers were validated in a set of 92 rice lines and converted into CAPS markers which can be used in blast resistance breeding programme. 相似文献
78.
Harvinder Singh Rupesh K. Deshmukh Abhinay Singh Ashok K. Singh Kishor Gaikwad Tilak R. Sharma Trilochan Mohapatra Nagendra K. Singh 《Molecular breeding : new strategies in plant improvement》2010,25(2):359-364
Simple sequence repeats (SSR) are the DNA markers of choice for genetic analysis in rice (Oryza sativa L.) due to their abundance, high polymorphism and simple assays using agarose gel electrophoresis. In an attempt to find
most variable SSR loci for the agarose gel system, the relationship between SSR length and level of polymorphism was evaluated
in a set of eight diverse rice genotypes using 201 random SSR loci of different repeat motifs and lengths, representing both
genic and intergenic sequences from the 12 rice chromosomes. There was a positive correlation between SSR length and average
number of alleles per locus but linearity of this relationship was limited to the SSR length range of 10–70 bp. The highest
level of polymorphism was in the SSR length range of 51–70 bp, beyond which there was stabilization and then decline of polymorphism
in SSRs longer than 70 bp. Proportion of polymorphic loci in the different SSR length groups also followed similar pattern
with even sharper decline of polymorphism in the highest size range. Here we describe a genome wide set of 436 validated highly
variable SSR (HvSSR) markers with repeat lengths of 51–70 bp for their consistent amplification and high polymorphism. In
the parental lines of three different mapping populations, the HvSSR loci showed more than twice the level of polymorphism
than random SSR markers with average repeat length of 34 bp, and therefore are suitable for QTL mapping and fingerprinting
studies in rice employing agarose gels. 相似文献
79.
Anuradha Singh Pradeep K. Singh Rakesh Singh Awadhesh Pandit Ajay K. Mahato Deepak K. Gupta Kuldeep Tyagi Ashok K. Singh Nagendra K. Singh Tilak R. Sharma 《Molecular breeding : new strategies in plant improvement》2010,26(2):325-338
Betaine aldehyde dehydrogenase (BADH) is a key enzyme involved in the synthesis of glycinebetaine—a powerful osmoprotectant
against salt and drought stress in a large number of species. Rice is not known to accumulate glycinebetaine but it has two
functional genes coding for the BADH enzyme. A non-functional allele of the BADH2 gene located on chromosome 8 is a major factor associated with rice aroma. However, similar information is not available
regarding the BADH1 gene located on chromosome 4 despite the similar biochemical function of the two genes. Here we report on the discovery and
validation of SNPs in the BADH1 gene by re-sequencing of diverse rice varieties differing in aroma and salt tolerance. There were 17 SNPs in introns with
an average density of one per 171 bp, but only three SNPs in exons at a density of one per 505 bp. Each of the three exonic
SNPs led to changes in amino acids with functional significance. Multiplex SNP assays were used for genotyping of 127 diverse
rice varieties and landraces. In total 15 SNP haplotypes were identified but only four of these, corresponding to two protein
haplotypes, were common, representing more than 85% of the cultivars. Determination of population structure using 54 random
SNPs classified the varieties into two groups broadly corresponding to indica and japonica cultivar groups, aromatic varieties clustering with the japonica group. There was no association between salt tolerance and the common BADH1 haplotypes, but aromatic varieties showed specific
association with a BADH1 protein haplotype (PH2) having lysine144 to asparagine144 and lysine345 to glutamine345 substitutions. Protein modeling and ligand docking studies show that these two substitutions lead to reduction in the substrate
binding capacity of the BADH1 enzyme towards gamma-aminobutyraldehyde (GABald), which is a precursor of the major aroma compound
2-acetyl-1-pyrroline (2-AP). This association requires further validation in segregating populations for potential utilization
in the rice breeding programs. 相似文献
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