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241.
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Martina G. Ramirez Celina M. Oliveri Dina Mismar Amy Barsoum Jasmin Abdulla 《Invertebrate reproduction & development.》2013,57(2):96-103
Male Mastophora cornigera exit egg sacs as adults, which allowed us to determine spiderling sex ratios and patterns of maternal investment in this species. We collected 15 egg sacs produced by seven mothers, which yielded 1945 emergent spiderlings which were sexed, 1850 of which were weighed. Two emergent broods were significantly male and female biased and were unaffected by pre-emergence mortality. The weights of male and female spiderlings differed in eight broods, with males and females being heavier in four cases each. Five of these broods were derived from multiple egg sac sets produced by one mother, and in each case, the total mean male and female spiderling weights for all broods in a set were biased in the same direction as the biased brood(s) within that set. Mean emergent spiderling weight was independent of brood size and sex ratio for both males and females. Despite such independence, sex allocation in M. cornigera can favor sons, daughters, or both equally, and by numbers, by weight, or both at once. The proximate mechanisms and adaptive significance of such variability is unknown. We also review evidence for gender-biased allocations in arachnid offspring and suggested mechanisms for their applicability to M. cornigera. 相似文献
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用聚类分析和主成分分析法对阿尔泰山两河源自然保护区地面生地衣群落进行划分;根据优势地衣种类进行群落命名。应用典范对应分析法探讨了地面生地衣种类分布与环境间的关系。结果表明:阿尔泰山两河源自然保护区地面生地衣可分为以下4个群落:白腹地卷+硫石蕊+喇叭粉石蕊群落;茸珊瑚枝+长根地卷+黑瘿地卷群落;土星猫耳衣+软鹿蕊+膜地卷群落;雪岛衣+北方石蕊+绿皮地卷群落。各群落中的地面生地衣种类与盖度,在一定程度上反映了地面生地衣在阿尔泰山两河源保护区分布格局与环境的关系。典范对应分析结果表明,阿尔泰山地面生地衣群落物种分布受到土壤湿度、土壤pH、海拔高度、林冠层郁闭度和灌木层盖度等环境因素的影响,其中海拔、土壤湿度、林冠层郁闭度等对地衣物种分布的影响最大。 相似文献
245.
Khawla Abdulla Salem Anwar Qureshi Milos Ljubisavijevic Murat Oz Dmytro Isaev Munir Hussain Frank Christopher Howarth 《Molecular and cellular biochemistry》2010,340(1-2):115-123
Alloxan is widely used to induce diabetes mellitus in experimental animals. Recent studies have provided evidence that alloxan has direct actions on cardiac muscle contraction. The aim of this study was to further investigate the mechanisms underlying the effects of alloxan on ventricular myocyte shortening and intracellular Ca2+ transport. Amplitude of myocyte shortening was reduced in a dose-dependent manner as the concentration of alloxan was increased in the range 10?7–10?4 M. Amplitude of shortening was reduced (56.8 ± 6.6%, n = 27) by 10?6 M alloxan and was partially reversed during a 10 min washout. Amplitude of the Ca2+ transient was also reduced (79.7 ± 2.9%, n = 29) by 10?6 M alloxan. Caffeine-evoked sarcoplasmic reticulum Ca2+ release, fractional release of Ca2+, assessed by comparing the amplitude of electrically evoked with that of caffeine-evoked Ca2+ transients, and fura-2-cell length trajectory during the late stages of relaxation of myocyte twitch contraction were not significantly altered by alloxan. The amplitude of L-type Ca2+ current was not altered by alloxan. Alterations in sarcoplasmic reticulum Ca2+ transport, myofilament sensitivity to Ca2+, and L-type Ca2+ current do not appear to underlie the negative inotropic effects of alloxan. 相似文献
246.
根据野外调查和相关研究资料,对新疆准噶尔盆地五彩湾地区地衣进行了分类学研究,并报道3个中国新记录种:Caloplaca arenaria,Caloplaca boul yi,Candelariella aggregate.该文描述了3种地衣的形态解剖特征、化学特征和生境,并提供了相关彩色图片. 相似文献
247.
Faris Q. Alenzi Badi Q. Alenazi Fatma H. AL-anazy Abdulla M. Mubaraki Mohamed L. Salem Ali A. Al-Jabri Mahmoud Lotfy Mohammad S. Bamaga Mohammed W. AlRabia Richard K.H. Wyse 《Saudi Journal of Biological Sciences》2010,17(1):29-36
Caspases are key intracellular molecules in the control of apoptosis, but little is known concerning their relative contribution to the cascade of events leading to eosinophil apoptosis. We examined caspase-3, -8, and -9 activities in receptor ligation dependent apoptosis induction in the cultured eosinophils (CE). CE cultured alone for 48 hours exhibited constitutive apoptosis (12% ± 1.2). Significant (P < 0.05) enhancement of eosinophil apoptosis was observed following monoclonal antibody (Mab) treatment with CD45 (40% ± 0.7), CD95 (36% ± 1.6), or CD69 (34% ± 0.2). Caspase activity was analysed using the novel CaspaTagTM technique and flow cytometry. CE ligated with CD45 (Bra55), CD95 (Fas) and CD69 Mab resulted in caspase-3 and -9 activation after 16 hours post-ligation. This trend in caspase-3 and -9 activation continued to increase significantly through to the 20 and 24 hours time points when compared to isotype control. Activated up-stream caspase-8 was detected 16 and 20 hours after treatment with CD45, CD95 and CD69 Mab followed by a trend toward basal levels at 24 hours. Ligation of CD95 was followed by mitochondrial permeabilization, as demonstrated by marked increase in mitochondrial transmembrane potential (ΔΨm) at all time points. However, ligation with CD45 and CD69 failed to induce a change in ΔΨm at 16 hours post-treatment compared to isotype control even though there was an alteration in mitochondrial downstream-caspase activity following ligation with these Mab(s) at this time point. At 20 and 24 hours post-ligation, CD45 or CD69 induce significantly altered levels of ΔΨm. Thus, the intrinsic and extrinsic caspase pathways are involved in controlling receptor ligation-mediated apoptosis induction in human eosinophils, findings that may aid the development of a more targeted, anti inflammatory therapy for asthma. 相似文献
248.
Reis M. F. Abdulla M. Parr R. M. Chatt A. Dang H. S. Machado A. A. S. C. 《Biological trace element research》1994,43(1):481-487
Biological Trace Element Research - Advances in analytical methodology and sophisticated instrumentation introduced during the last few decades have not only helped to recognize the presence of a... 相似文献
249.
John Burt Aaron Bartholomew Abdulla Saif 《Journal of experimental marine biology and ecology》2009,373(1):72-78
Artificial reefs are increasingly being promoted as a means to mitigate impacts from human activities in coastal urban areas. Coastal defense structures such as breakwaters are becoming recognized as large-scale artificial reefs that support abundant and diverse marine communities and play important roles in coastal ecology and management. However, there is limited understanding of how substrate materials used to construct artificial reefs or breakwaters can influence the development of habitat-forming benthic organisms. To assess the influence of substrata on coral recruitment and overall benthic community development, we deployed standard-size tiles of materials used in the construction of breakwaters and artificial reefs (concrete, gabbro, granite, and sandstone), along with terra-cotta for comparative purposes, at two breakwaters (DDD, PRT) and two natural reef sites (NR1, NR2) in Dubai, United Arab Emirates, for one year. Kruskal-Wallis ANOVA with post-hoc Mann-Whitney U-tests were used to examine differences in coral recruitment among sites and materials. Coral recruitment was highest at the DDD (4.9 ± 0.5 recruits 100 cm− 2), while recruitment was low and did not differ among other sites (PRT: 0.1 ± 0.04, NR1:0.3 ± 0.1, NR2: 0.1 ± 0.03 recruits 100 cm− 2). There were significant differences in coral recruitment among materials at DDD, where gabbro had higher recruit densities than concrete and sandstone; sandstone also contained less coral recruits than terra-cotta. Variability associated with low coral recruit densities precluded significant differences among materials at other sites. Overall benthic community structure differed more as a result of differences among sites than among substrate materials. Higher community dissimilarity was observed among sites than among material in SIMPER analysis, and significant differences were only observed among sites in ANOSIM. Univariate comparison of the benthos correlated with community differences in NMS ordination also showed significant differences among sites but not material. Overall, these results indicate that site-specific differences in recruitment patterns are more important in determining early benthic community structure and coral recruitment than are differences among substrate material. However, where coral recruitment is high, these results suggest that gabbro should be used preferentially over concrete or sandstone where it is feasible, but that granite may be a suitable alternative where it is the dominant stone. Coral recruitment on terra-cotta was comparable to all materials but sandstone, supporting its continued use in recruitment studies. These results also indicate that using stone amenable to coral recruitment is unlikely to influence the wider benthic community. 相似文献
250.
Usama Abdulla David Talbert Mary Lucas Mary Mullarkey 《BMJ (Clinical research ed.)》1972,3(5830):797-799
In-vitro experiments have been undertaken to assess the effect of ultrasound at diagnostic and therapeutic levels on chromosomes of human lymphocyte cultures. The frequency used was about 2 MHz. The intensity was that of diagnostic level, 23 mW/cm2, which was increased stepwise to 3·5 W/cm2. The time of exposure varied from two to eight hours. No difference could be detected between the numbers of cells with aberrations in the insonated and control cultures, but aggregation of red cells was observed at high intensities. 相似文献