植物冷锻炼对于胁强敏感度的影响(英文)

前文由柑桔枝条在不同低温下、不同冷冻时间的电解质外渗测定,提出胁强(stress)、作用时间与胁变(strain)之间关系的数学模型。在这个模型中共有3个参数:屈服点温度(yield point temperature),胁强敏感度(stress sensitivity)和作用时间敏感度(sensitivity to duration),用以描述植物的抗性。抗性强的植物应表现为屈服点温度较低,胁强敏感度或者时间敏感度较低。为验证此数学模型,本工作以经冷锻炼与未经冷锻炼的盆栽柑桔枝条为材料,作不同温度与时间处理的电解质外渗率的测定,研究了冷锻炼对于上述3个参数的影响。发现胁强敏感度和屈服点温度受冷锻炼影响而下降,时间敏感度未表现明显变化。对于田间柑桔、油桐与毛竹的定期测定,在固定冷冻时间下,得到了类似于盆栽柑桔的结果。入冬时,植物抗冻性提高,3种植物都表现出下列两种变化:1.胁强敏感度的明显下降;2.屈服点温度和/或时间敏感度亦下降。开春时的变化则相反。胁强敏感度的变化与后一种变化有各自的规律,且因植物种类而不同。拐点胁强(stress at inflection point)具有与半致死温度(50％killing point temperature)不同的意义,它的变化是上述两种变化的综合结果。本试验结果表明,冷锻炼对于植物胁强敏感度有明显影响,用本数学模型的3个抗性指标描述     

生态梯度轴(EGA)用于林木生态遗传的研究——CA方法估算EGA(CA_1)和EGA(r~2)

应用典型相关的原理和技术,将多元地理坐标和生态因子降维成1元,研究提出2个生态梯度轴(EGA);EGA(CA_1)和EGA(r~2)。通过白榆20个种源的2个EGA估算,它们与6个环境因子平均相关系数为0.8551和0.8804,复相关系数0.9998和0.9985,很好地综合了诸环境因子在对群体7个性状分析结果,EGA能很好描述梯度变异,证明了白榆种群属于连续变异模式。     

A new species of <Emphasis Type="Italic">Cosmospora</Emphasis> and the first record of sexual state of <Emphasis Type="Italic">C. lavitskiae</Emphasis>

A new fungicolous species, Cosmospora inonoticola, is described and illustrated based on a specimen collected from northeast China. It is characterized by the occurrence of fruitbodies of Inonotus sp.; perithecia nonstromatic, subglobose to pyriform, not collapsing when dry; clavate asci containing (3–)6(?8) spores; ascospores ellipsoidal to broadly ellipsoidal, pale brown, finely warted, bicellular, conspicuously constricted at septum; and producing a verticillium-like asexual state. A multi-locus analysis of the combined ITS, rpb1 and tub sequences confirmed its taxonomic position, and revealed the distinction from its morphologically similar species including the type species, C. coccinea, which occurs also on Inonotus. A specimen with sexual state of C. lavitskiae is reported for the first time, and a reference specimen is indicated.     

中国陕西省新异蚖属一新种记述(原尾纲,古蚖目,古蚖科)

记述了采自陕西省翠华山的新异蚖属1新种,即陕新异蚖Neanisentomonshaanicum sp.nov.。新种主要特征为:前足跗节感器b′-1和c′缺失,感器d极长大;腹部第Ⅴ～Ⅵ节背板缺少前排刚毛A3,毛序为8/16,第Ⅶ节背板缺少前排刚毛A1和A3,毛序为6/16;雌性外生殖器具有明显的鸭头状的头片。该新种可以通过前足跗节感器d的长度和雌性外生殖器等特征与已知种类区分。文中同时列出了新异蚖属的世界种类检索表。     

Expression of Hsf1, Hsf2, and Phlda1 in cells undergoing cryptorchid-induced apoptosis in rat testes

Surgery‐induced cryptorchidism, in which the testes are prevented from descending into the scrotal sac, results in testicular germ cell death, and it is commonly used as an experimental tool in the study of spermatogenesis. However, the molecular events underlying the activation of germ cell death remain poorly understood. In the present study, we investigate selective cell loss from cryptorchid rat testis by using DNA flow cytometry and by determining protein and mRNA expression of Hsf1, Hsf2, and Phlda1. The hypo‐haploid cell fraction is significantly decreased as early as 3 days after surgical induction of cryptorchidism (from 42.01 ± 5.74% to 15.98 ± 3.88%), followed by a significant decrease in the haploid cell fraction at Day 7. At the latter time point, an apoptotic peak of spermatocytes appears in DNA histograms just before the tetraploid peak; the percentage of aneuploid cells between diploid and tetraploid rises as high as 14.05 ± 2.98% of the total cells in 7‐day cryptorchid testis, suggesting that a large number of spermatocytes are undergoing apoptosis. The expression of Phlda1 mRNA is significantly elevated 3 days after induction of cryptorchidism. After 7 days of cryptorchidism, Hsf1 and Phlda1 are strongly expressed in the nucleus and cytoplasm, respectively, of primary spermatocytes. Numerous apoptotic spermatocytes are also observed at this time point. These results suggest that the Hsf1/Phlda1 pathway plays an important role in the apoptosis of primary spermatocytes in cryptorchid testis. We present evidence suggesting that Hsf2 is also involved in germ cell removal in cryptorchid testis. Mol. Reprod. Dev. 78:283–291, 2011. © 2011 Wiley‐Liss, Inc.     

Single injection of naked plasmid encoding alpha-melanocyte-stimulating hormone protects against thioacetamide-induced acute liver failure in mice

Oxidative stress has been implicated in the propagation of acute liver injury. The aim of our study was to investigate whether gene transfer of alpha-melanocyte-stimulating hormone (alpha-MSH), a potent anti-inflammatory peptide, could prevent fulminant hepatic failure in mice. Acute liver damage was induced by intraperitoneal administration of thioacetamide. Hydrodynamics-based gene transfection with alpha-MSH expression plasmid via rapid tail vein injection was initiated 1 day prior to intoxication. The mortality in the alpha-MSH-treated mice was significantly lower compared to the vehicle group 3 days after injury. Liver histology significantly improved and TUNEL-positive hepatocytes decreased in the treated mice. The degradation of IkappaBalpha, endogenous inhibitor of nuclear factor kappaB, and upregulation of inducible nitric oxide synthase and tumor necrosis factor-alpha mRNA levels were prevented in the alpha-MSH-treated group, indicating decreased oxidative stress and inflammation. These results suggest alpha-MSH gene therapy might protect against acute hepatic necroinflammatory damage with further potential applications.     

What an rRNA Secondary Structure Tells about Phylogeny of Fungi in Ascomycota with Emphasis on Evolution of Major Types of Ascus

Background

RNA secondary structure is highly conserved throughout evolution. The higher order structure is fundamental in establishing important structure-function relationships. Nucleotide sequences from ribosomal RNA (rRNA) genes have made a great contribution to our understanding of Ascomycota phylogeny. However, filling the gaps between molecular phylogeny and morphological assumptions based on ascus dehiscence modes and type of fruitbodies at the higher level classification of the phylum remains an unfulfilled task faced by mycologists.

Methodology/Principal Findings

We selected some major groups of Ascomycota to view their phylogenetic relationships based on analyses of rRNA secondary structure. Using rRNA secondary structural information, here, we converted nucleotide sequences into the structure ones over a 20-symbol code. Our structural analyses together with ancestral character state reconstruction produced reasonable phylogenetic position for the class Geoglossomycetes as opposed to the classic nucleotide analyses. Judging from the secondary structure analyses with consideration of mode of ascus dehiscence and the ability of forming fruitbodies, we draw a clear picture of a possible evolutionary route for fungal asci and some major groups of fungi in Ascomycota. The secondary structure trees show a more reasonable phylogenetic position for the class Geoglossomycetes.

Conclusions

Our results illustrate that asci lacking of any dehiscence mechanism represent the most primitive type. Passing through the operculate and Orbilia-type asci, bitunicate asci occurred. The evolution came to the most advanced inoperculate type. The ascus-producing fungi might be derived from groups lacking of the capacity to form fruitbodies, and then evolved multiple times. The apothecial type of fruitbodies represents the ancestral state, and the ostiolar type is advanced. The class Geoglossomycetes is closely related to Leotiomycetes and Sordariomycetes having a similar ascus type other than it was originally placed based on nucleotide sequence analyses.     

Tubocapsenolide A, a novel withanolide, inhibits proliferation and induces apoptosis in MDA-MB-231 cells by thiol oxidation of heat shock proteins

Tubocapsenolide A (TA), a novel withanolide-type steroid, exhibits potent cytotoxicity against several human cancer cell lines. In the present study, we observed that treatment of human breast cancer MDA-MB-231 cells with TA led to cell cycle arrest at G(1) phase and apoptosis. The actions of TA were correlated with proteasome-dependent degradation of Cdk4, cyclin D1, Raf-1, Akt, and mutant p53, which are heat shock protein 90 (Hsp90) client proteins. TA treatment induced a transient increase in reactive oxygen species and a decrease in the intracellular glutathione contents. Nonreducing SDS-PAGE revealed that TA rapidly and selectively induced thiol oxidation and aggregation of Hsp90 and Hsp70, both in intact cells and in cell-free systems using purified recombinant proteins. Furthermore, TA inhibited the chaperone activity of Hsp90-Hsp70 complex in the luciferase refolding assay. N-Acetylcysteine, a thiol antioxidant, prevented all of the TA-induced effects, including oxidation of heat shock proteins, degradation of Hsp90 client proteins, and apoptosis. In contrast, non-thiol antioxidants (trolox and vitamin C) were ineffective to prevent Hsp90 inhibition and cell death. Taken together, our results demonstrate that the TA inhibits the activity of Hsp90-Hsp70 chaperone complex, at least in part, by a direct thiol oxidation, which in turn leads to the destabilization and depletion of Hsp90 client proteins and thus causes cell cycle arrest and apoptosis in MDA-MB-231 cells. Therefore, TA can be considered as a new type of inhibitor of Hsp90-Hsp70 chaperone complex, which has the potential to be developed as a novel strategy for cancer treatment.     

苜蓿假盘菌侵染苜蓿叶片的细胞学研究

采用微分干涉相差显微镜、扫描和透射电镜技术系统研究了苜蓿假盘菌Pseudopeziza medicaginis在苜蓿叶片的侵染过程及超微结构特征。结果表明,接种4h后,子囊孢子萌发产生芽管;12h后,芽管以直接侵入的方式进入表皮细胞形成侵染菌丝;24h后,表皮细胞中侵染菌丝向相邻表皮细胞扩展,同时侵入到叶肉细胞以胞内生长方式扩展;接种72h后,侵染菌丝在表皮细胞下的叶肉组织中形成初始菌落;第5d后,菌丝扩展至整个叶片组织,大量菌丝聚集形成子座组织,并进一步形成子囊盘与子囊。病菌菌丝在侵入寄主细胞初期,并不     

Androgenesis,gynogenesis, and parthenogenesis haploids in cucurbit species

Haploids and doubled haploids are critical components of plant breeding. This review is focused on studies on haploids and double haploids inducted in cucurbits through in vitro pollination with irradiated pollen, unfertilized ovule/ovary culture, and anther/microspore culture during the last 30 years, as well as comprehensive analysis of the main factors of each process and comparison between chromosome doubling and ploidy identification methods, with special focus on the application of double haploids in plant breeding and genetics. This review identifies existing problems affecting the efficiency of androgenesis, gynogenesis, and parthenogenesis in cucurbit species. Donor plant genotypes and surrounding environments, developmental stages of explants, culture media, stress factors, and chromosome doubling and ploidy identification are compared at length and discussed as methodologies and protocols for androgenesis, gynogenesis, and parthenogenesis in haploid and double haploid production technologies.