芦笋性别决定与性别分化研究进展

从芦笋性别表现及其决定的遗传基础、性别分化途径,性别决定基因的定位以及性别分化特异表达基因的分离与分析等方面来综述芦笋性别决定与性别分化最新研究进展。目前,已构建了围绕芦笋性别决定基因M比较精细的遗传图谱,将M定位在L5染色体着丝点附近的0.63 cM区域内,并构建了含有8个跨叠克隆群的物理图谱,但由于大量重复序列的存在,跨叠克隆之间的空隙不能闭合;同时先后分离得到11个芦笋花器官发育特异表达基因,并通过序列分析和原位杂交等技术对这些基因的功能进行了分析。最后,对今后进一步研究提出了建议。     

Sex Determination by Sex Chromosomes in Dioecious Plants

Abstract: Sex chromosomes have been reported in several dioecious plants. The most general system of sex determination with sex chromosomes is the XY system, in which males are the heterogametic sex and females are homogametic. Genetic systems in sex determination are divided into two classes including an X chromosome counting system and an active Y chromosome system. Dioecious plants have unisexual flowers, which have stamens or pistils. The development of unisexual flowers is caused by the suppression of opposite sex primordia. The expression of floral organ identity genes is different between male and female flower primordia. However, these floral organ identity genes show no evidence of sex chromosome linkage. The Y chromosome of Rumex acetosa contains Y chromosome-specific repetitive sequences, whereas the Y chromosome of Silene latifolia has not accumulated chromosome-specific repetitive sequences. The different degree of Y chromosome degeneration may reflect on evolutionary time since the origination of dioecy. The Y chromosome of S. latifolia functions in suppression of female development and initiation and completion of anther development. Analyses of mutants suggested that female suppressor and stamen promoter genes are localized on the Y chromosome. Recently, some sex chromosome-linked genes were isolated from flower buds of S. latifolia.     

Multiple microRNAs Regulate the Floral Development and Sex Differentiation in the Dioecious Cucurbit Coccinia grandis (L.) Voigt

Plant Molecular Biology Reporter - Despite having a small genome and heteromorphic sex chromosomes, the molecular basis of sex differentiation in the dioecious cucurbit, Coccinia grandis, largely...     

雌雄异株植物性别决定相关功能基因研究进展

雌雄异株植物是植物性别决定机制及演化的重要研究材料,通过分子生物学技术分离性别决定的相关基因是揭示雌雄异株植物性别决定的关键问题之一.近10年来已经分离到了多个性染色体连锁的基因DD44X/Y、SlX/Y3、SlX/Y4、MROS3、SLZPT2-1、SLZPT4-1.尽管这些基因都存在于性染色体上,但是对其功能分析发现这些基因并不是性别决定的关键基因,而是性别决定控制系统中的成员之一.另外MADS-box基因也和性别特征器官的建成有关.本文对这些基因的结构及在性别决定中的功能研究进行综述和分析,并对可能的新的研究方向进行评价.     

Inferring the Genetic Basis of Sex Determination from the Genome of a Dioecious Nightshade

Dissecting the genetic mechanisms underlying dioecy (i.e., separate female and male individuals) is critical for understanding the evolution of this pervasive reproductive strategy. Nonetheless, the genetic basis of sex determination remains unclear in many cases, especially in systems where dioecy has arisen recently. Within the economically important plant genus Solanum (∼2,000 species), dioecy is thought to have evolved independently at least 4 times across roughly 20 species. Here, we generate the first genome sequence of a dioecious Solanum and use it to ascertain the genetic basis of sex determination in this species. We de novo assembled and annotated the genome of Solanum appendiculatum (assembly size: ∼750 Mb scaffold N50: 0.92 Mb; ∼35,000 genes), identified sex-specific sequences and their locations in the genome, and inferred that males in this species are the heterogametic sex. We also analyzed gene expression patterns in floral tissues of males and females, finding approximately 100 genes that are differentially expressed between the sexes. These analyses, together with observed patterns of gene-family evolution specific to S. appendiculatum, consistently implicate a suite of genes from the regulatory network controlling pectin degradation and modification in the expression of sex. Furthermore, the genome of a species with a relatively young sex-determination system provides the foundational resources for future studies on the independent evolution of dioecy in this clade.     

罗非鱼性别决定及分化的研究进展

对罗非鱼的性别决定和分化的研究现状和研究成果进行综述,并探讨了在罗非鱼性别决定研究上的研究趋势。     

线虫的性别分化和决定

线虫（Caeborhabditis elegans)是十分重要的模式生物。在遗传学,发育生物学以及神经生物学中有着广泛的应用。就线虫性别分化和性别决定相关基因的特性和功能进行了详细介绍,并在此基础上初步概括了其性别决定的分子机制。     

Molecular Cytogenetic Characterization of the Dioecious Cannabis sativa with an XY Chromosome Sex Determination System

Hemp (Cannabis sativa L.) was karyotyped using by DAPI/C-banding staining to provide chromosome measurements, and by fluorescence in situ hybridization with probes for 45 rDNA (pTa71), 5S rDNA (pCT4.2), a subtelomeric repeat (CS-1) and the Arabidopsis telomere probes. The karyotype has 18 autosomes plus a sex chromosome pair (XX in female and XY in male plants). The autosomes are difficult to distinguish morphologically, but three pairs could be distinguished using the probes. The Y chromosome is larger than the autosomes, and carries a fully heterochromatic DAPI positive arm and CS-1 repeats only on the less intensely DAPI-stained, euchromatic arm. The X is the largest chromosome of all, and carries CS-1 subtelomeric repeats on both arms. The meiotic configuration of the sex bivalent locates a pseudoautosomal region of the Y chromosome at the end of the euchromatic CS-1-carrying arm. Our molecular cytogenetic study of the C. sativa sex chromosomes is a starting point for helping to make C. sativa a promising model to study sex chromosome evolution.     

A Male-Associated DNA Sequence in a Dioecious Plant, Cannabis sativa L.

Male-associated DNA sequences were analyzed in a dioecious plant,Cannabis sativa L. (family: Moraceae), which is known to havesex chromosomes. DNA was isolated from male and female plantsand subjected to random amplification of polymorphic DNA. Twoout of 15 primers yielded fragments of 500 and 730 bp whichwere detected in all male plants but not in any of the femaleplants tested. These two DNA fragments were cloned and usedas probes in gel blot analysis of genomic DNA. When the maleand female DNAs were allowed to hybridize with the 500-bp probe,no differences in patterns were observed between male and femaleplants. By contrast, when these DNAs were allowed to hybridizewith the 730-bp probe, much more intense bands specific to maleplants were detected, in addition to less intense bands thatwere common to both sexes. The 730-bp DNA fragment was namedMADCl (male-associated DNA sequence in Cannabis sativa). Thesequence of MADCl did not include a long open reading frameand it exhibited no significant similarity to previously reportedsequences. (Received May 8, 1995; Accepted September 18, 1995)     

植物性染色体进化及性别决定基因研究进展

植物性染色体起源于1对常染色体, 其在不同雌雄异株植物中多次起源并独立演变, 是研究性染色体起源和进化机制的理想材料。过去的研究在一定程度上阐明了植物性染色体的起源和演化动力; 且性染色体遗传退化、性别决定基因以及剂量补偿效应正逐渐成为研究的热点。近年来, 关于植物性染色体进化及性别决定基因的研究取得了一些重要进展。该文综述了植物性染色体的起源、进化、遗传退化、剂量补偿效应以及性别决定基因等, 并对植物性染色体进化研究发展趋势进行了展望。     

甲壳动物性别分化的遗传决定及外界因素的影响(英文)

本文综述了甲壳动物的性别决定机理及外界因素对性别分化的影响。绝大多数甲壳动物没有明显的性染色体 ,促雄腺被认为是甲壳动物性别分化的最主要的决定因子 ,其作用已得到了广泛的证明。由于甲壳动物幼体在早期发育过程中具有向两性发育的潜能 ,促雄腺可以决定个体未来发育的性别 ,并且通过人为摘除或移植促雄腺的方法可以使性别已经分化的个体发生性逆转 ,从而改变幼体的性别。虽然甲壳动物的性别是由遗传决定的 ,但外界的因素比如寄生、光周期、温度或激素可以改变其性比 ,其中以寄生的影响研究比较多 ,并认为是影响某些甲壳动物性别分化的主要外界因子。由于大多数养殖的甲壳动物雌雄性之间有体重和体长的差异 ,在水产养殖中可以利用这些特征进行全雌或全雄种苗的生产 ,以提高产量和效益。     

Studio Anatomico delle Reazioni Indotte dalla Decapitazione Combinata a 2,4-D in Turioni di Asparagus Officinalis L

Summary

1) Young stems of Asparagus officinalis L., from 12 to 46 cm. in length, were decapitated just below the shoot apex and 2,4-D was applied to the cut surface in concentrations 0,1% to 2% by weight in lanolin paste. Decapitated Asparagus stems treated with lanolin only served as controls. A total of 50 stems, of which 10 controls, were investigated.

2) Apart from the sprouting of lateral buds in two plants, no other macroscopical or histological reaction was noticed in the control material. Following treatment with 2,4-D, on the contrary, the following gross responses were evidently seen

a) Bending reaction (figs. 2, 3, 5). This was found to occur in 13 plants, on the second to fourth day since decapitation and at a distance of 1 to 5 cm. from the cut surface. Only in one case was the bending so pronounced as to bring about a complete change in polarity of the upper portion of the stem;

b) Tumor formation. In 8 plants, 7 of which had been treated with doses 1% or 2% of 2,4-D, a swelling appeared just below the surface of decapitation. Due to a difference in cell elongation between the cells of the fundamental parenchyma and those of the cortex, the cut surface took, in a few days, a spoon-like appearance (fig. 10). In two of the 8 plants a tumor-like swelling was noted at some distance from decapitation (fig. 11);

c) Unbalanced elongation in fasciated stems. This brought about the bending towards the cut surface of the more elongated portion in fasciated stems (fig. 15);

d) Longitudinal splits in fasciated stems. (figs. 12, 13). Longitudinal splits were noticed in some of the fasciated stems, which appeared also affected by a very strong gummosis;

e) Survival of decapitated stems. 2,4-D treatment clearly increases the survival of decapitated stems, the maximum duration of survival being 19 days in controls and 30 to 33 days in some stems treated with 1% or 2% phyto-hormone;

f) Sprouting of lateral buds (figs. 4, 5). The frequency of this phenomenon in 2,4-D treated material is not higher as compared with that of controls. However, the treatment seems to induce some auxinlike responses in lateral branches.

3) Concerning the histological reactions, the following can be said

a) No mitosis stimulation is induced neither by wounding alone nor by wounding plus 2,4-D in any portion of the Asparagus stem;

b) radial cell elongation of cortical cells and, in some cases, of pericycle cells (Borgstrom's «transverse reaction») is responsible for both sub-terminal tumors and the two tumor-like swellings of the type reported in fig. 11 (fig. 20 for histological details). Differential elongation in different portions of the stem is responsible for some of the gross responses referred to above;

c) extensive lignification and suberization of parenchyma and, sometimes, epidermal cells occur in 2,4-D treated material. Lignification begins, on the 12th to the 15th day since decapitation, in the cells of the pericycle and fundamental parenchyma surrounding the outermost bundles and gradually spreads centripetally reaching, in extreme cases, some portions of the pith (fig. 24). In these same cases, the lignification process (which is generally present in the first 2 or 3 cm. below the cut surface) may extend as far as 7 cm. below the surface of decapitation. The lignification process appears not to be spred evenly in the stem, being sometimes localized in one or more large areas (fig. 18) and expressing itself in highest degree in zones near the divergence of leaf traces (fig. 16). Lignification of cortical parenchyma and of isolated groups of epidermal cells occurs in a later stage, being concomitant with some suberization process in other cells of the same region of the stem. Photographs of different patterns of both suberization and lignification processes in the layers from epidermis to outermost bundles are reported in figs. 26 to 31, all taken from material treated with 2% 2,4-D. The lignification process takes place according to the well-known scheme of «vascular differentiation» (Sinnot e Bloch 1945);

d) gummosis is very common in 2,4-D treated material. The various stages of gummosis in the different tissues of the stem have been described and special attention has been paid to the extensive formation of lysigenous spaces, following cell degeneration (figs. 32 to 37).

4) In discussing the results of the present investigation, the point is stressed that by experimental means it has been possible to induce in Asparagus some patterns of tissue differentiation and distribution which are to be found in other species of Monocotyledons. After taking into special consideration the actually available data on «vascular differentiation», a twofold effect of 2,4-D on this process is assumed to have taken place, namely: a) favouring influence on cell wall lignification and b) prolongation of survival, probably bringing about a kind of «aging» of tissues. This prolongation of survival seems also to have been a determining factor in the occurrence of the strong gummosis noticed.     

An Integrated Approach to Crop Genetic Improvement

The balance between the supply and demand of the major food crops is fragile,fueling concerns for long-term global food security.The rising population,increasing wealth and a proliferation of nonfood uses(e.g.bioenergy) has led to growing demands on agriculture,while increased production is limited by greater urbanization,and the degradation of land.Furthermore,global climate change with increasing temperatures and lower,more erratic rainfall is projected to decrease agricultural yields.There is a predicted need to increase food production by at least 70% by 2050 and therefore an urgent need to develop novel and integrated approaches,incorporating high-throughput phenotyping that will both increaseproduction per unit area and simultaneously improve the resource use efficiency of crops.Yield potential,yield stability,nutrient and water use are all complex multigenic traits and while there is genetic variability,their complexity makes such traits difficult to breed for directly.Nevertheless molecular plant breeding has the potential to deliver substantial improvements,once the component traits and the genes underlying these traits have been identified.In addition,interactions between the individual traits must also be taken into account,a demand that is difficult to fulfill with traditional screening approaches.Identified traits will be incorporated into new cultivars using conventional or biotechnological tools.In order to better understand the relationship between genotype,component traits,and environment over time,a multidisciplinary approach must be adopted to both understand the underlying processes and identify candidate genes,QTLs and traits that can be used to develop improved crops.     

温度依赖型性别决定在爬行动物中的研究进展

爬行动物性别决定方式主要有遗传依赖型性别决定(genetic sex determination,GSD)和环境依赖型性别决定(environmental sex determination,ESD),而ESD又以温度依赖型性别决定(temperature sex determination,TSD)为主。研究爬行动物TSD有助于人们弄清楚环境条件对物种表型的影响,从而更好地利用环境条件和遗传基础的共同机制来人为的改善或者诱导具TSD型物种的进化方向,以实现自然和人类的最大利益。该篇综述从母系活动、气候变化(全球气候变暖)、类固醇以及TSD机制四个方面总结了近年来关于爬行动物TSD的最新研究。