水牛腔前卵泡的分离方法

为确定水牛腔前卵泡的有效分离方法 ,作者取用来自屠宰场 31头水牛的 6 1个卵巢 ,先用剪刀去掉髓质部 ,然后分别用梳刮法、剪碎法和显微分离法分离回收腔前卵泡。结果发现 ,使用梳刮法时 ,平均每个水牛卵巢回收所得的腔前卵泡数 (15 2 35± 4 4 81)明显高于剪碎法 (32 6 2± 14 81)和显微分离法 (8 95± 3 4 4 ) ,且其平均每个卵巢的处理时间 (39 0 5± 4 2 7min)明显少于剪碎法 (4 6 4 3± 4 15min)和显微分离法 (4 4 5 5± 7 82min)。梳刮法分离所得的腔前卵泡中 ,以原始卵泡最多 (占 4 1 2 5 % ) ,其次为初级卵泡 (占 38 79% ) ,而次级卵泡最少 (仅占 19 95 % )。用梳刮法获得的腔前卵泡在体外培养 72h后 ,存活率为 5 6 38% ,与剪碎法(4 8 91% )及显微分离法 (5 9 34% )没有显著差异。用梳刮法处理 10头黄牛的 2 0个卵巢 ,平均每个卵巢可分离获得 1195 2 0± 6 85 0 0个腔前卵泡 ,明显多于水牛的 15 2 35± 4 4 81个腔前卵泡。由此可见 ,梳刮法是水牛腔前卵泡的有效分离方法     

西藏拉果错卤虫的繁殖特征与成体形态特征

在标准培养条件下研究了西藏拉果错卤虫的繁殖特征和成体形态特征。发现西藏拉果错卤虫与山西解池卤虫及美国大盐湖卤虫在性成熟时间上有较大不同 ,表现为最早抱对时间和最早产F1 代时间均出现较晚 ,且两者间隔时间较长 ,这是对该地区寒冷气候条件的适应。描述了拉果错卤虫雌雄成体的形态特征 ,其中雄性成体选取了 1 2个特征 ,雌性成体选取了 1 3个特征 ,并与世界上几个主要两性生殖卤虫种的成体形态特征做了比较 ,结果显示西藏拉果错卤虫的雌雄成体属于较大的类型 ,但并不像其卵和无节幼体那样显著大于其它品系。聚类分析的结果表明拉果错卤虫的雄性成体和雌性成体均与山西解池卤虫距离最近 ,与伊朗乌尔米湖卤虫距离最远     

大眼华鳊和伍氏华鳊的形态差异及其物种有效性

分别对大眼华鳊和伍氏华鳊 137尾标本 7个可数性状和 18个可量性状进行主成分分析 ,以探讨这两个种之间的形态差异及其物种有效性。研究结果显示 :无论是在可数性状上还是可量性状上 ,大眼华鳊和伍氏华鳊之间的形态差异并不显著 ,而且大眼华鳊大陆的标本和台湾的标本无明显的不同。此表明 ,大眼华鳊和伍氏华鳊应该为同一个种。根据国际动物命名法规 ,伍氏华鳊应是大眼华鳊的次定同物异名。     

Preservation of the morphological and molecular stability of embryonic tissues

There is presently great interest in using early embryonic tissues, particularly human tissue, for studies of protein and gene expression. Embryonic human tissue is very fragile, and delays often occur before it can be properly prepared for scientific study. Using chick embryos, we have studied the effects of delaying fixation or biochemical isolation on the preservation of cytological characteristics and biochemical molecules. Our study shows that by 60 min post-harvest, tissue morphology and immunofluorescence staining degrades, but the total mRNA profile remains stable. This study suggests that the time between removal of the tissue and fixation is critical to the results and that the critical time is much shorter for embryonic tissues than for more developed tissues. Our results have implications for all research where embryonic tissues are harvested but not processed immediately.     

Ectomycorrhizal syntheses with Picea abies and three fungal species: a case study on the use of an in vitro technique to identify naturally occurring ectomycorrhizae

Ectomycorrhizal syntheses between Picea abies and the fungal associates Scleroderma citrinum, Boletus luridus, and Tricholoma vaccinum were carried out using Melin's Erlenmeyer flask technique. The symbioses of S. citrinum were characterized by a mantle composed of an outer prosenchymatous and an inner synenchymatous layer. The mantles of B. luridus and T. vaccinum were solely prosenchymatous. Rhizomorphs were produced in all treatments, but only in association with S. citrinum were they differentiated with additional, enlarged hyphae. All synthesized ectomycorrhizae were white or whitish to light orange and greyishorange. On large-scale root sampling in two differing Picea abies forests in Switzerland, nine out of a total of 22 morphological types of ectomycorrhizae were white or yellow in colour and were, therefore, comparable with the synthesized ectomycorrhizae. These nine natural types generally had distinct mantle features (irregular synenchyma, gelatinous matrix, cystides, thick-walled hyphae), but mostly lacked clamp connections. Synthesized ectomycorrhizae, on the other hand, lacked distinct mantle characteristics and always had clamp connections. Natural and synthesized white or yellow ectomycorrhizae did not coincide morphologically and thus identification of the fungal partners of natural symbioses by means of in vitro-synthesis with potential ectomycorrhizal fungi was not possible in the present study.     

Effect of restrictive conditions on the growth and morphology of a temperature-sensitive mannose-requiring mutant of Aspergillus nidulans

When incubated at 45 degrees C in the absence of added mannose, pregrown hyphae of a temperature-sensitive, mannose-relief mutant (mnrA455) of Aspergillus nidulans grew normally for a short time (4-5 h) before exhibiting an abnormal morphology consisting of the production by hyphae of discrete spherical swellings called balloons. These swellings could be up to 10 microns in diameter and were produced either at or behind the hyphal apex. Often only one swelling was produced in association with each hyphal tip, but in a significant minority of cases (approximately 19.6%) a second balloon was produced in close association with the first. Hyphal tip extension slowed before and during balloon formation, but growth at individual tips did not usually stop when a balloon began to be formed in the same hypha. All tip extension ceased after approximately 8 h in cultures maintained at 45 degrees C. However, normal growth resumed 45-60 min after transfer of such a culture to the permissive temperature of 37 degrees C even after 48 h at 45 degrees C. Electron microscopic examination indicated that balloons consistently had thicker walls than the surrounding hyphae but that no accumulation of cytoplasmic vesicles was apparent within them. This indicates that a modification of wall structure, probably including deposition of new wall material, was caused by a mannose deficiency, but that this altered wall synthesis and attendant hyphal swelling was not due to diversion of the normal vesicle-mediated tip-extension system to the side walls of hyphae.     

Vital Parameters Assessments of Starvation Tolerance of <i>in vitro Populus alba</i> Culture

Populus alba is a large woody deciduous plant. The plant has been introduced to shooting, then multiplication of rooting on Murashige and Skoog (MS) medium. This work was designed to estimate the effect of two factors (low levels of 1-Naphthaleneacetic acid NAA and sucrose) on P. alba response resulting in 6 treatments compared to the control, with twelve measured responses. There was a significant difference in some measurements in morphology, like plantlets fresh-weight, shoot-, root-length, and leaf number. In the physiological measurements, there were significant differences in all the measured parameters. The low concentrations of sucrose and media composition/power (MS grams/L) led to starvation in plants; however, these conditions led to enhancement in some morphological and physiological parameters to overcome the starvation effect, compared to the control. The RAPD-PCR molecular marker (four decamers) was used to evaluate the new individuals’ genetic variation (instability), resulting in a total polymorphism percentage of 50.83%. It was formerly known that the plantlets were identical to each other and to the mother plant. In this study, however, the use of distinct media power, hormonal and sucrose levels resulted in molecular variation reflected in P. alba’s morphological and physiological responses.     

LIFE HISTORY VARIATIONS IN A PREDOMINANTLY GAMETOPHYTIC POPULATION OV IRIDAEA CORDATA (GIGARTINACEAE, RHODOPHYTA)1

An Iridaea cordata ( Turner) Bory population made up of 83% gametophytes and 17% tetrasporophytes demonstrated little variation in these proportions over three years. These data contrast with an expectation that alternations of generations, as demonstrated by culture studies, should result in equal numbers of isomorphic generations. Analyses of reproductive and demographic attributes of the population were made to better understand the role of alternation of generations in this population .
Growth and mortality rates in the summer could not account for the success of gametophytes. however, size class frequencies demonstrated that tetrasporophytes were smaller individuals. Sporelings recruited into this intertidal region and made up 20% of the spring population numbers. Even with this level of recruitment, gametophyte-to-tetrasporophyte ratios did not change. Perennating holdfasts regenerated 80% of the spring number and 90% of the total blade area. Consequently, perennation and differential survival of gametophyte spores or sporelings are proposed as mechanisms maintaining gatnetophyte dominance in this San Juan Island, Washington population .     

Morphological and anatomical differentiation ofVellozia hirsuta populations (Velloziaceae)

The morphological and leaf anatomical differentiation ofVellozia hirsuta is analysed and classified into several types (A1, A2, A4, B3, B5, C3). The species has a relatively wide distribution in the campos rupestres of Minas Gerais in Brazil. The variation of the isolated populations on different mountain ranges is complex, does not follow a clear geographical pattern, and defies taxonomic classification.     

Demographic history and local adaptation of Myripnois dioica (Asteraceae) provide insight on plant evolution in northern China flora

The flora of northern China forms the main part of the Sino‐Japanese floristic region and is located in a south–north vegetative transect in East Asia. Phylogeographic studies have demonstrated that an arid belt in this region has promoted divergence of plants in East Asia. However, little is known about how plants that are restricted to the arid belt of flora in northern China respond to climatic oscillation and environmental change. Here, we used genomic‐level data of Myripnois dioica across its distribution as a representative of northern China flora to reconstruct plant demographic history, examine local adaptation related to environmental disequilibrium, and investigate the factors related to effective population size change. Our results indicate M. dioica originated from the northern area and expanded to the southern area, with the Taihang Mountains serving as a physical barrier promoting population divergence. Genome‐wide evidence found strong correlation between genomic variation and environmental factors, specifically signatures associated with local adaptation to drought stress in heterogeneous environments. Multiple linear regression analyses revealed joint effects of population age, mean temperature of coldest quarter, and precipitation of wettest month on effective population size (Ne). Our current study uses M. dioica as a case for providing new insights into the evolutionary history and local adaptation of northern China flora and provides qualitative strategies for plant conservation.