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841.
According to the ultrastructural characteristic observation of the developing male germ cells, spermatogenesis of the crustacean
shrimp, Fenneropenaeus chinensis, is classified into spermatogonia, primary spermatocytes, secondary spermatocyte, four stages of spermatids, and mature sperm.
The basic protein transition during its spermatogenesis is studied by transmission electron microscopy of ammoniacal silver
reaction and immunoelectron microscopical distribution of acetylated histone H4. The results show that basic protein synthesized
in cytoplasm of spermatogonia is transferred into the nucleus with deposition on new duplicated DNA. In the spermatocyte stage,
some nuclear basic protein combined with RNP is transferred into the cytoplasm and is involved in forming the cytoplasmic
vesicle clumps. In the early spermatid, most of the basic protein synthesized in the new spermatid cytoplasm is transferred
into the nucleus, and the chromatin condensed gradually, and the rest is shifted into the pre-acrosomal vacuole. In the middle
spermatid, the nuclear basic protein linked with DNA is acetylated and transferred into the proacrosomal vacuole and assembled
into the acrosomal blastema. At the late spermatid, almost all of the basic protein in the nucleus has been removed into the
acrosome. During the stage from late spermatid to mature sperm, some de novo basic proteins synthesized in the cytoplasm belt
transfer into the nucleus without a membrane and almost all deposit in the periphery to form a supercoating. The remnant histone
H4 accompanied by chromatin fibers is acetylated in the center of the nucleus, leading to relaxed DNA and activated genes
making the nucleus non-condensed. 相似文献
842.
Pavlik R Wypior G Hecht S Papadopoulos P Kupka M Thaler C Wiest I Pestka A Friese K Jeschke U 《Histochemistry and cell biology》2011,136(3):289-299
Estradiol and progesterone mediate their actions by binding to classical nuclear receptors, estrogen receptor α (ERα) and
estrogen receptor β (ERβ) and progesterone receptor A and B (PR-A and PR-B) and the non-classical G protein-coupled estrogen
receptor (GPER). Several animal knock-out models have shown the importance of the receptors for growth of the oocyte and ovulation.
The aim of our study was to identify GPER in human granulosa cells (GC) for the first time. Moreover, the effect of different
doses of gonadotropins on estrogen and progesterone receptors in the human ovary should be investigated as follicle stimulating
hormone (FSH) and luteinizing hormone (LH) are also responsible for numerous mechanisms in the ovary like induction of the
steroid biosynthesis. Human GC were cultured in vitro and stimulated with different doses of recombinant human FSH or LH.
Receptor expression was analyzed by immunocytochemistry and quantitative real-time RT-PCR. GPER could be identified for the
first time in human GC. It could be shown that high concentrations of LH increase GPER protein expression. Furthermore FSH
and LH increased ERβ, PR-A and PR-B significantly on protein level. These findings were verified for high doses of FSH and
LH on mRNA level. ERα was not affected with FSH or LH. We assume that gonadotropins induce GPER, ERβ and PR in luteinized
granulosa cells. 相似文献
843.
Beblo K Douki T Schmalz G Rachel R Wirth R Huber H Reitz G Rettberg P 《Archives of microbiology》2011,193(11):797-809
In this study, we investigated the ability of several (hyper-) thermophilic Archaea and phylogenetically deep-branching thermophilic
Bacteria to survive high fluences of monochromatic UV-C (254 nm) and high doses of ionizing radiation, respectively. Nine
out of fourteen tested microorganisms showed a surprisingly high tolerance against ionizing radiation, and two species (Aquifex pyrophilus and Ignicoccus hospitalis) were even able to survive 20 kGy. Therefore, these species had a comparable survivability after exposure to ionizing radiation
such as Deinococcus radiodurans. In contrast, there was nearly no difference in survival of the tested strains after exposure to UV-C under anoxic conditions.
If the cells had been dried in advance of UV-C irradiation, they were more sensitive to UV-C radiation compared with cells
irradiated in liquid suspension; this effect could be reversed by the addition of protective material like sulfidic ores before
irradiation. By exposure to UV-C, photoproducts were formed in the DNA of irradiated Archaea and Bacteria. The distribution
of the main photoproducts was species specific, but the amount of the photoproducts was only partly dependent on the applied
fluence. Overall, our results show that tolerance to radiation seems to be a common phenomenon among thermophilic and hyperthermophilic
microorganisms. 相似文献
844.
Sandra G Brauer Marjorie H Woollacott Robyn Lamont Sandy Clewett John O'Sullivan Peter Silburn George D Mellick Meg E Morris 《BMC neurology》2011,11(1):90
Background
Difficulty performing more than one task at a time (dual tasking) is a common and disabling problem experienced by people with Parkinson disease (PD). If asked to perform another task when walking, people with PD often take shorter steps or walk more slowly. Currently there is uncertainty about whether clinicians should teach people with PD to avoid dual tasking or whether they should encourage them to practice dual tasking with the hope that practice will lead to enhanced performance. This study will address this issue by comparing single to dual task gait training. 相似文献845.
Plum is a highly perishable fruit and postharvest fruit softening limits its shelf life. The aim of this work was to study
the specific effects of 1-methylcyclopropene (1-MCP) treatment on physiological changes in ‘Zaohong’ plums. Plums were treated
with 500 nL L−1 1-MCP at 20°C for 18 h followed by 20°C storage. The results showed that 1-MCP treatment significantly reduced endogenous
ethylene production and the activities of ethylene biosynthetic enzymes’ (1-aminocyclopropane-1-carboxylic acid synthase,
ACS and 1-aminocyclopropane-1-carboxylic acid oxidase, ACO) in plum fruit during storage when compared with untreated fruit.
Although 1-MCP treatment inhibited ethylene production and 1-aminocyclopropane-1-carboxylic acid (ACC) accumulation, it did
not inhibit the accumulation of N-malonyl-ACC (MACC). Higher firmness was also found in 1-MCP-treated plums than in controls. During storage, superoxide anion
(O2−·) and hydrogen peroxide (H2O2) levels decreased in 1-MCP-treated fruit. 1-MCP treatment also regulated superoxide dismutase (SOD) and catalase (CAT) activities
during storage. Xylanase activity was upregulated while activities of polygalacturonase (PG), pectin methyl esterase (PME)
and cellulase enzymes in the fruit were downregulated by 1-MCP treatment. In conclusion, 1-MCP might be a potent compound
for extending both storage period and shelf life of ‘Zaohong’ plums by suppressing ethylene biosynthesis, regulating cell
wall degradation enzymes and reducing fruit softening. 相似文献
846.
Phloem loading is the process by which photoassimilates synthesized in the mesophyll cells of leaves enter the sieve elements
and companion cells of minor veins in preparation for long distance transport to sink organs. Three loading strategies have
been described: active loading from the apoplast, passive loading via the symplast, and passive symplastic transfer followed
by polymer trapping of raffinose and stachyose. We studied phloem loading in Amborella trichopoda, a premontane shrub that may be sister to all other flowering plants. The minor veins of A. trichopoda contain intermediary cells, indicative of the polymer trap mechanism, forming an arc on the abaxial side and subtending a
cluster of ordinary companion cells in the interior of the veins. Intermediary cells are linked to bundle sheath cells by
highly abundant plasmodesmata whereas ordinary companion cells have few plasmodesmata, characteristic of phloem that loads
from the apoplast. Intermediary cells, ordinary companion cells, and sieve elements form symplastically connected complexes.
Leaves provided with 14CO2 translocate radiolabeled sucrose, raffinose, and stachyose. Therefore, structural and physiological evidence suggests that
both apoplastic and polymer trapping mechanisms of phloem loading operate in A. trichopoda. The evolution of phloem loading strategies is complex and may be difficult to resolve. 相似文献
847.
Alireza Sharif Hamed Haddad Kashani Elahe Nasri Zahra Soleimani Mohammad Reza Sharif 《Probiotics and antimicrobial proteins》2017,9(4):380-385
Diarrhea is considered as an important cause of morbidity and mortality, even though one of the main reasons of death following diarrhea is initiated by dysentery. In recent years, the consumption of probiotics has been proposed for the treatment of infectious diarrhea. Despite most of the studies on probiotics have focused on acute watery diarrhea, few studies in the field of dysentery have found beneficial effects of probiotics. This study is a randomized double-blind clinical trial. The patients were randomly placed into control and case groups. In the intervention group, the patients received probiotics in the form of Kidilact® sachet, which contained high amounts of 7-strain friendly bacteria strains of Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus bulgaricus, Bifidobacterium infantis, Bifidobacterium breve, and Streptococcus thermophiles. On the other hand, the patients in the control group received placebo sachets on a daily basis for 5 days. It is notable that the treatment protocol of acute dysentery was done on both groups. The results of this study showed significant differences in the duration of blood in diarrhea between probiotic consumers (2.62 days) and the control group (3.16 days) (P value = 0.05). Additionally, significant differences in the average length of hospitalization in probiotic consumers (3.16 days) and control (3.66 days), (P value = 0.02) could be claimed that the consumption of probiotics is effective in reducing the duration of dysentery and diarrhea. The results of this study suggest that the use of probiotics can be effective in reducing the duration of blood in diarrhea. This study was also recorded in the Iran center of clinical trials registration database (IRCT2014060617985N1). 相似文献
848.
High salinity is an environmental factor that inhibits plant growth and development, leading to large losses in crop yields.
We report here that mutations in SIZ1 or PHO2, which cause more accumulation of phosphate compared with the wild type, enhance tolerance to salt stress. The siz1 and pho2 mutations reduce the uptake and accumulation of Na+. These mutations are also able to suppress the Na+ hypersensitivity of the sos3-1 mutant, and genetic analyses suggest that SIZ1 and SOS3 or PHO2 and SOS3 have an additive effect on the response to salt stress. Furthermore, the siz1 mutation cannot suppress the Li+ hypersensitivity of the sos3-1 mutant. These results indicate that the phosphate-accumulating mutants siz1 and pho2 reduce the uptake and accumulation of Na+, leading to enhanced salt tolerance, and that, genetically, SIZ1 and PHO2 are likely independent of SOS3-dependent salt signaling. 相似文献
849.
We have investigated the local and regional scale genetic structure of Siberian primrose (Primula nutans) populations in Northern Europe. The genetic diversity and structure of fifteen populations sampled from the Bothnian Bay
in Finland, the Barents Sea in Norway and the White Sea in Russia were assessed using eleven microsatellite markers. We investigated
the distribution of genetic variation within and between populations, and studied the local genetic structure using spatial
autocorrelation analysis. We found very low genetic and allelic diversity in the Bothnian Bay and Barents Sea populations,
and only slightly higher in the White Sea population. The level of genetic differentiation between the regions was very high,
whereas differentiation between the populations within the regions was moderate. We found no spatial structuring of populations
in any region suggesting efficient dispersal on a local scale. Clonal reproduction seemed to have no effect on genetic structure. 相似文献
850.
Nino Asatiani Tamar Kartvelishvili Marina Abuladze Lali Asanishvili Nelly Sapojnikova 《Biological trace element research》2011,142(3):388-397
The changes in glutathione-dependent cycle enzymes and catalase activities under Cr(VI)-induced oxidative stress were investigated
in two distinct cell lines: L-41−human epithelial-like cells and HLF−fetal human diploid lung fibroblasts, which differ in
tissue origin, proliferation, and antioxidant enzymes activities. The chromium concentrations from 1 to 5 μM cause nontoxic
effects and activate antioxidant enzymes to overcome oxidative stress. In spite of some differences in the endogenous antioxidant
activities, both cell lines reveal the same range of toxic concentrations (20–30 μM). The irreversible inhibition of glutathione-dependent
antioxidant enzymes develops under toxic concentrations and serves as a marker of toxicity. The endogenous antioxidant activity
influences time-dependent expression of Cr(VI) toxicity and the dynamics of antioxidant enzymes activity under nontoxic conditions.
The cell antioxidant defense system is an important marker of the cell adaptive capacity under nontoxic and toxic conditions. 相似文献