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101.
Ultrastructural changes of spermatids during spermiogenesis in a freshwater stingray, Himantura signifer, are described. Differentiation of spermatids begins with modification of the nuclear envelope adjacent to the Golgi apparatus,
before the attachment of the acrosomal vesicle. A fibrous nuclear sheath extends over the nuclear surface from the site of
acrosomal adherence. The conical apical acrosome is formed during nuclear elongation. At the same time, chromatin fibers shift
from an initially random arrangement, assume a longitudinal orientation, and become helical before final nuclear condensation.
An axial midpiece rod is formed at the posterior end of nucleus and connects to the base of the sperm tail. Numerous spherical
mitochondria surround the midpiece axis. The tail originating from the posterior end of the midpiece is composed of the usual
9 + 2 axoneme accompanied by two longitudinal columns, which are equal in size and round in cross section. The two longitudinal
columns are absent at the end piece. A distinctive feature of freshwater stingray sperm is its spiral configuration. 相似文献
102.
Sadagopal S Amara RR Kannanganat S Sharma S Chennareddi L Robinson HL 《Journal of virology》2008,82(8):4149-4153
In this study, we monitored the temporal breadths, frequencies, and functions of antiviral CD4 and CD8 T cells in 2 of 22 DNA/modified vaccinia virus Ankara-vaccinated macaques that lost control of a simian-human immunodeficiency virus 89.6P challenge by 196 weeks postchallenge. Our results show that both mutation and exhaustion contributed to escape. With the reappearance of viremia, responding CD8 and CD4 T cells underwent an initial increase and then loss of breadth and frequency. Antiviral gamma interferon (IFN-gamma)- and interleukin 2-coproducing cells were lost before IFN-gamma-producing cells and CD4 cells before CD8 cells. At euthanasia, all CD8, but no CD4, Gag epitopes detected during long-term control contained mutations. 相似文献
103.
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105.
Effects of human pregnancy on cardiac autonomic function above and below the ventilatory threshold 总被引:1,自引:0,他引:1
Avery N. D.; Wolfe L. A.; Amara C. E.; Davies G. A. L.; McGrath M. J. 《Journal of applied physiology》2001,90(1):321-328
This study examined the effectsof human pregnancy on heart rate variability (HRV), spontaneousbaroreflex (SBR) sensitivity, and plasma catecholamines at rest andduring exercise. Subjects were 14 healthy, physically active pregnantwomen (PG; mean gestational age = 33.9 ± 1.0 wk). Resultswere compared with an age-matched nonpregnant control group (NPG;n = 14) with similar characteristics. Theelectrocardiographic R-wave-R-wave interval and systolic blood pressure (via finger plethysmograph) were measured on a beat-to-beat basis at rest and during upright cycling at 60 and 110% of the ventilatory threshold (Tvent). Parasympathetic nervoussystem (PNS) modulation (as reflected by HRV high-frequency/total power and SBR slope) was significantly reduced at rest in the PG vs. the NPG.During exercise, PNS modulation decreased significantly in both groups,but the magnitude of PNS withdrawal from rest to 110%Tvent was smaller in the PG vs. NPG. Sympathetic nervous system (SNS) modulation (reflected by the low-frequencypower-to-high-frequency power ratio) increased above resting values at60 and 110% Tvent in the NPG. SNS modulation at 110%Tvent was significantly lower in the PG compared with theNPG. Plasma norepinephrine and epinephrine levels were also lower at110% Tvent in the PG. It was concluded that healthypregnant women exhibit lower PNS modulation at rest and blunted SNSmodulation during exercise above Tvent in late gestation. 相似文献
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107.
Sirilug Magerd Monsicha Somrit Parichat Prachaney Amara Thongpan Kannika Chatchavalvanich Prapee Sretarugsa Wattana Weerachatyanukul 《Cell and tissue research》2009,336(2):267-276
Our aim has been to determine whether carbohydrate distribution in the oviducts of progesterone-treated animals is comparable
with that of seasonal breeders in Rana tigrina. Like many other anurans, R. tigrina oviduct exhibits a short straight portion (pars recta, pr) at the beginning followed by a long, highly coiled portion (pars
convoluta, pc). Histologically, the oviduct of this species revealed some unique features, one of which was intense toluidine
blue staining, specifically in the upper mucosal glands of pc4. Based on lectin reactivities in the epithelial cells and mucosal
glands, patterns of lectin staining in the seasonal breeders were classified into seven types: R1-R3 (for pr) and C1-C4 (for
pc). Typically, some lectins reacted selectively either with ciliated cells (concanavalin A) or non-cialiated cells (Ricinus communis agglutinin I and wheatgerm agglutinin); however, Bandeiraea simplicifolia agglutinin I reacted with both cell types. These staining patterns were different in the progesterone-treated animals. Differences
in glycan distribution in the oviductal secretions were revealed by lectin blotting. Compared with the seasonal breeders,
an enhanced staining of some lectins was noted in the hormone-treated animals: either an increased staining intensity of existing
protein bands or additional staining of new protein bands. Inversely, the staining of wheatgerm agglutinin was markedly diminished
in the hormone-treated animals, suggesting the inhibitory effect of progesterone on oviductal glycan distribution. Whether
alteration in glycan distribution upon progesterone treatment affects the physiological properties of the released jelly substances
remains to be addressed.
This research was supported by Thailand Research Funds (to W.W.), a Research Initiate Grant from Kasetsart University (to
A.T.), and Mahidol University. 相似文献
108.
Comparative performance of δ13C,ion accumulation and agronomic parameters for phenotyping durum wheat genotypes under various irrigation water salinities 下载免费PDF全文
Z. Chamekh C. Karmous S. Ayadi A. Sahli M. Belhaj Fraj S. Yousfi S. Rezgui N. Ben Aissa M.D. Serret I. McCann Y. Trifa H. Amara J.L. Araus 《The Annals of applied biology》2017,170(2):229-239
The use of efficient selection traits for screening under contrasting irrigation water salinity is a challenge for breeders. To identify patterns, grain yield (GY) and yield components (kernels m?2, thousand kernels weight), growth traits (plant height, biomass), flag leaf ion accumulation (Na+ and K+), carbon isotope composition (δ13Cgrain) and nitrogen concentration (Ngrain) of grains were assessed on 25 durum wheat genotypes (G) in two consecutive growing seasons (2010 and 2011), in three semi‐arid locations in Tunisia. Each location differed in their irrigation water salinity as measured by electrical conductivity: Echbika (S1, 6 dS m?1), Barrouta (S2, 12 dS m?1) and Sidi Bouzid (S3, 18 dS m?1). GY was shown to be negatively correlated to Ngrain as well as to δ13Cgrain. This is confirmed by a multiple linear regression analysis that showed that both δ13Cgrain and Ngrain were the major determinant components for GY variability under S3. A high genotypic variability was observed and the improved genotype Maali exhibited the most stable GY under the three irrigation water salinities and the two cropping seasons. Maali showed the lowest δ13Cgrain. This indicates that tolerance in durum wheat is likely to be correlated to the ability of maintaining a high stomatal conductance. According to our data suggests δ13Cgrain can be used for an efficient screening of salt tolerant durum wheat. Under our experimental conditions, Ngrain was shown to be highly correlated to δ13Cgrain and can therefore be easier‐to‐use trait to assess the tolerance to salinity. 相似文献
109.
110.
Eleuch L Jilal A Grando S Ceccarelli S Schmising Mv Tsujimoto H Hajer A Daaloul A Baum M 《植物学报(英文版)》2008,50(8):1004-1014
The objective of this study was to investigate the genetic diversity of barley accessions.Additionally,association trait analysis was conducted for grain yield under salinity,heading date and plant height.For this purpose,48 barley genotypes were analyzed with 22 microsatellite simple sequence repeat (SSR) markers.Four of the 22 markers (Bmac316,scssr03907,HVM67 and Bmag770) were able to differentiate all barley genotypes.Cluster and principal coordinate analysis allowed a clear grouping between countries from the same region.The genotypes used in this study have been evaluated for agronomic performance in different environments.Conducting association analysis for grain yield under salinity conditions using TASSEL software revealed a close association of the marker Bmag749 (2H,bin 13) in two different environments with common significant alleles (175,177),whereas the HVHOTR1 marker (2H,bin 3) was only significant in Sakhar_Egypt with alleles size being 158 and 161.Heading date also showed an association with scssr03907 through the common significant specific allele 111 and EBmacO415 markers in three different agro climatic locations,whereas HVCMA,scssr00103 and HVM67 were linked to heading date in the Egyptian environment only.The plant height association analysis revealed significant markers Bmag770 via the significant allele 152 and scssr09398. 相似文献