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31.
Devos N Tans C Momin P Plisnier M Weynants V Feron C Poolman JT 《Microbes and infection / Institut Pasteur》2012,14(11):979-988
Neisseria meningitidis may be classified according to the lipooligosaccharide immunotype. We show that this classification can be achieved by PCR genotyping of the genes involved in the lipooligosaccharide inner-core biosynthesis, lpt3, lpt6, lgtG and lot3. Genotyping data correlated well (90-100%) with mass spectrometry data and was, therefore, applied to screen a random subset of recent N. meningitidis serogroup B isolates from Europe. Analysis of the proportion of the different lipooligosaccharide types highlighted the predominance of L3 strains. Surprisingly, high rates of L2 type strains were found in Spain (17%, versus 2.5% in Germany and 1.9% in the United Kingdom). Therefore, we also investigated further these Spanish L2 strains in an attempt to explain such prevalence despite the known sensitivity of L2 immunotype to complement. We explored the hypothesis that these strains express high amounts of factor H-binding protein (fHbp), but we found, on the contrary, that L2 strains express low or undetectable amounts of fHbp. Our findings suggest that, in addition to a genetic analysis, a multivalent approach may be necessary to estimate the effectiveness of a N. meningitidis serogroup B vaccine. 相似文献
32.
33.
Drosophila Heterochromatin Protein 1 (HP1)/Origin
Recognition Complex (ORC) Protein Is Associated with HP1 and ORC and
Functions in Heterochromatin-induced Silencing 总被引:5,自引:0,他引:5 下载免费PDF全文
Mohammed Momin Shareef Chadwick King Mona Damaj RamaKrishna Badagu Da Wei Huang Rebecca Kellum 《Molecular biology of the cell》2001,12(6):1671-1685
Heterochromatin protein 1 (HP1) is a conserved component of the highly compact chromatin of higher eukaryotic centromeres and telomeres. Cytogenetic experiments in Drosophila have shown that HP1 localization into this chromatin is perturbed in mutants for the origin recognition complex (ORC) 2 subunit. ORC has a multisubunit DNA-binding activity that binds origins of DNA replication where it is required for origin firing. The DNA-binding activity of ORC is also used in the recruitment of the Sir1 protein to silence nucleation sites flanking silent copies of the mating-type genes in Saccharomyces cerevisiae. A fraction of HP1 in the maternally loaded cytoplasm of the early Drosophila embryo is associated with a multiprotein complex containing Drosophila melanogaster ORC subunits. This complex appears to be poised to function in heterochromatin assembly later in embryonic development. Here we report the identification of a novel component of this complex, the HP1/ORC-associated protein. This protein contains similarity to DNA sequence-specific HMG proteins and is shown to bind specific satellite sequences and the telomere-associated sequence in vitro. The protein is shown to have heterochromatic localization in both diploid interphase and mitotic chromosomes and polytene chromosomes. Moreover, the gene encoding HP1/ORC-associated protein was found to display reciprocal dose-dependent variegation modifier phenotypes, similar to those for mutants in HP1 and the ORC 2 subunit. 相似文献
34.
Zain Ul Abidin Habib Ul Hassan Zubia Masood Naseem Rafique Bilal Ahamad Paray Karim Gabol Muhammad Ishaq Ali Shah Aneela Gulnaz Asim Ullah Talha Zulfiqar Mohammad Abdul Momin Siddique 《Saudi Journal of Biological Sciences》2022,29(4):3075
Rainbow trout Oncorhynchus mykiss has a great nutritional value and delicious taste. A 90-days experimental trial was conducted to investigate the effect of dietary leaf extract of neem tree Azadirachta indica as a feeding supplement on the growth performance and proximate composition of O. mykiss. Four experimental diets were designed as T1 (with 5% A. indica leaf extract), T2 (with 7% of A. indica leaf extract), T3 (with 10% A. indica leaf extract), and T4 (control group feed with a regular diet with 0% A. indica leaf extract). The average initial weight of fry 0.4 ± 0.14 g was stocked at 25 fish/tank with two replicates per treatment (4 × 2 = 8). After 90 days of the experimental trial, One-way ANOVA showed significant differences in final body weight, weight gain, specific growth rate, feed conversion ratio, and survival rate among the treatment groups (p < 0.05). The highest final body weight (48.10 g) and weight gain (47.70 g) was observed in T2 with 7% A. indica leaf extract, which was significantly different from the other treatments (p < 0.05). The lowest FCR was recorded in T2 (1.90), which was significantly different compared to other treatment groups (p < 0.05). Inclusion of A. indica leaf extract in formulated feed for rainbow trout had significant effects in the hepatosomatic index, viscerosomatic index and Fulton’s condition factor (p < 0.05), but there was no significant difference in the survival rate of rainbow trout fry treated with different experimental diets (p > 0.05). The phenomenal regression indicates that 7.5% A. indica inclusion is optimum for best growth performance for rainbow trout under a controlled environment. Thus, the present study suggests that the dietary leaf extract has performed an excellent nutritional supplement by enhancing growth performance and health conditions of rainbow trout in the hatchery conditions. 相似文献
35.
A mouse genomic clone containing a lactate dehydrogenase-A (LDH-A)
processed pseudogene and a B1 repetitive element was isolated, and a
nucleotide sequence of approximately 3 kb was determined. The pseudogene
and B1 element are flanked by perfect 13-bp repeats, and the B1 sequence
starts at 14 nucleotides 3' to the presumptive polyadenylation signal of
the pseudogene. The nucleotide sequences of the LDH-A genes and processed
pseudogenes from mouse, rat, and human were compared, and a phylogenetic
tree was constructed. The rate and pattern of nucleotide substitutions in
the LDH-A pseudogenes are similar to previously reported results (Li et al.
1984). The average rate of nucleotide substitutions in the LDH-A
pseudogenes is 4.3 X 10(- 9)/site/year. The substitutions of C----T and
G----A are most frequent, and A----G substitutions are relatively high. The
rate of synonymous substitutions in the LDH-A genes is 5.3 X 10(-9), which
is not significantly higher than the average rate of 4.7 X 10(-9) for 35
mammalian genes. The rate of nonsynonymous substitutions in the LDH-A genes
is 0.20 X 10(-9), which is considerably lower than the average rate of 0.88
X 10(-9) for 35 mammalian genes. Thus, the mammalian LDH-A gene appears to
be highly conserved in evolution.
相似文献
36.
The glucose transport system of the hyperthermophilic anaerobic bacterium Thermotoga neapolitana 总被引:1,自引:1,他引:0 下载免费PDF全文
The glucose transport system of the extremely thermophilic anaerobic bacterium Thermotoga neapolitana was studied with the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DOG). T. neapolitana accumulated 2-DOG against a concentration gradient in an intracellular free sugar pool that was exchangeable with external source of energy, such as pyruvate, and was inhibited by arsenate and gramicidin D. There was no phosphoenolpyruvate-dependent phosphorylation of glucose, 2-DOG, or fructose by cell extracts or toluene-treated cells, indicating the absence of a phosphoenolpyruvate:sugar phosphotransferase system. These data indicate that D-glucose is taken up by T. neapolitana via an active transport system that is energized by an ion gradient generated by ATP, derived from substrate-level phosphorylation. 相似文献
37.
Snetselaar, K. M., Bolker, M., and Kahmann, R. 1996. Ustilago maydis mating hyphae orient their growth toward pheromone sources. Fungal Genetics and Biology 20, 299-312. When small drops of Ustilago maydis sporidia were placed 100-200 μm apart on agar surfaces and covered with paraffin oil, sporidia from one drop formed thin hyphae that grew in a zig-zag fashion toward the other drop if it contained sporidia making the appropriate pheromone. For example, a2b2 mating hyphae grew toward a1b1 and a1b2 mating hyphae, and the filaments eventually fused tip to tip. Time-lapse photography indicated that the mating hyphae can rapidly change orientation in response to nearby compatible sporidia. When exposed to pheromone produced by cells in an adjacent drop, haploid sporidia with the a2 allele began elongating before sporidia with the a1 allele. Sporidia without functional pheromone genes responded to pheromone although they did not induce a response, and sporidia without pheromone receptors induced formation of mating hyphae although they did not form mating hyphae. Diploid sporidia heterozygous at b but not at a formed straight, rigid, aerial filaments when exposed to pheromone produced by the appropriate haploid sporidia. Again, the a2a2b1b2 strain formed filaments more quickly than the a1a1b1b2 strain. Taken together, these results suggest that the a2 pheromone diffuses less readily or is degraded more quickly than the a1 pheromone. 相似文献
38.
39.
Histochemical studies were carried out on some of the glycolytic enzymes viz. phosphorylase, aldose, alpha-glycerophosphate dehydrogenase (alpha-GPDH) and lactic dehydrogenase (LDH) and a key enzyme of the pentose phosphatase cycle, glucose-6-phosphate dehydrogenase (G-6-PDH), in the hepatopancreas of Scylla serrata (Forskal). 1. Weak activities of phosphorylase and aldolase and strong-activities of alpha-GPDH and LDH were noticed mainly in the brush border of the tubules and R-cell cytoplasm. A trace activity of G-6-PDH was noticed in the brush border. 2. Bilateral eyestalk removal results in inhibition of both phosphorylase and aldolase. However, enhanced activities of alpha-GPDH and LDH were noticeable 4 h after the operation. The G-6-PDH activity remained unaltered till 24 h. 3. Injection of eyestalk extract into both intact and destalked crabs activated all the enzymes. 相似文献
40.
Bhaskar K Shareef MM Sharma VM Shetty AP Ramamohan Y Pant HC Raju TR Shetty KT 《Neurochemistry international》2004,44(1):35-44
Munc18-1 (p67, nSec1, rbSec1), a neuron-specific 67kDa protein was independently identified as a syntaxin-binding protein, and as a component that co-purifies with, and regulates the kinase activity of cyclin dependent kinase (Cdk5). Gene knockout studies have demonstrated a role for Munc18-1 in synaptic vesicle docking and neurotransmitter release. Mice lacking Munc18-1 gene were synaptically silent, but the gene deletion did not prevent normal brain assembly, including the formation of layered structures, fiber pathways and morphologically defined synapses. Previous study has shown that Munc18-1 facilitates Cdk5 mediated phosphorylation of KSPXK domains of the neuronal cytoskeletal elements, suggesting that Munc18-1 may function in the regulation of cytoskeletal dynamics. Present study demonstrates the co-purification and co-localization of Munc18 with cytoskeletal elements and forms first step towards understanding the role for Munc18-1 in cytoskeletal dynamics. Conversely, the cytoskeletal proteins and Cdk5 co-purifies with Munc18-1 in a Munc18-1 immuno-affinity chromatography, suggesting a strong protein-protein interaction. Findings from immunofluorescence studies in PC12 cells have shown co-localization of Munc18-1 and Cdk5 with neurofilaments and microtubules. Further, immunohistochemical and immuno-electron microscopic studies of rat olfactory bulb also demonstrated co-localization of Munc18-1 and Cdk5 with cytoskeletal elements. Thus, the biochemical evidence of strong interaction between Munc18-1 with cytoskeletal proteins and morphological evidence of their (Munc18 and cytoskeletal elements) identical sub-cellular localization is suggestive of the possible role for Munc18-1 in cytoskeletal dynamics. 相似文献