环境变化对苔藓植物物种多样性的影响:以上海徐家汇地区为例

为了探讨区域环境变化对苔藓植物物种多样性的影响,作者通过文献查阅、实地调查、标本查检和鉴定,对20、21世纪初上海徐家汇地区苔藓植物种类组成进行了比较分析。结果表明,20世纪初该地区记载有24种苔藓植物,其中15种是以徐家汇为模式产地发表的新种,但目前仅有7种（包括6种1亚种）仍被接受;该地区现有21种苔藓植物分布。经历100年后,环境条件的改变对其苔藓植物物种多样性的影响并不显著,但却使其种类组成发生了根本性变化。20世纪初以徐家汇为模式产地的苔藓植物,目前除尖叶匍灯藓（Plagiomnium acutum）外,其余都已从其模式产地消失。而以葫芦藓科和真藓科为代表的土生苔藓植物数目明显增加。多种世界广布、抗干扰能力强的伴人苔藓植物成为主要种类。树附生苔藓植物的种类组成发生变化,种数也相对100年前明显减少。此外,作者对城市苔藓植物的保护提出了建议。     

Fertility response to photoperiod and temperature in indica photoperiod-sensitive male sterile rice

The aim of this work was to develop a photoperiod-sensitive male sterile rice with stable sterility. We developed Changguang S, an indica rice strain, by using a short critical day length. Differences in the fertility responses of Changguang S strain pollen to temperature and photoperiod under natural and controlled conditions were studied. The results showed that Changguang S strain exhibited stable sterility under long-day and low-temperature conditions (22°C, 15 days). The stability of sterility was significantly higher than that of other such rice strains, Nongken 58S and 7001S. The critical photoperiod for inducing male sterility in Changguang S was 13 h or shorter, and its duration was significantly shorter than that required for rice strains Nongken 58S and 7001S. It is suggested that Changguang S is a typical photoperiod-sensitive male sterile rice strain with a shorter critical day length and a lower critical temperature. It is promising to apply this strain to two-line hybrid rice production.     

Verification and tissue-specific expression of nifU-like gene from the amphioxus Branchiostoma belcheri

A nifU-like gene exhibiting similarity to nifU of nitrogen fixation gene cluster was identified for the first time from the gut cDNA library of amphioxus Branchiostoma belcheri. Both RT-PCR and Northern blotting as well as in situ hybridization histochemistry verified that the cDNA represents an amphioxus nifU-like gene rather than a microbial contaminant. The nifU-like gene encodes a protein of 164 amino acid residues including a highly conserved U-type motif (C-X26-C-X43-C), and shares 66-86% identity to NifU-like proteins from a variety of species including vertebrates, invertebrates and microbes. It is expressed in a tissue-specific manner in the digestive system including epipharyngeal groove, endostyle, hepatic caecum and hind-gut and in the gill, ovary and testis. Taken together, it is highly likely that NifU-like protein plays some tissue-dependent and critical role in amphioxus.     

Microsatellite DNA loci from the typical halophyte <Emphasis Type="Italic">Thellungiella salsuginea</Emphasis> (Brassicaceae)

Thellungiella salsuginea (Brassiaceae) is a typical halophyte which can tolerate extreme cold, drought, and salinity. In order to understand the adaptive evolution of this species in the arid habitats, it is important to know its genetic structure. In this study, 17 polymorphic microsatellite loci were isolated and characterized from an enrichment genomic library of this species. We further assessed the polymorphisms of each locus in 18 individuals from nine geographically distant populations. The number of alleles per locus ranged from six to fourteen. The observed and expected heterozygosity ranged from 0.17 to 0.28 and 0.32 to 0.45, respectively. These markers have been crossly checked in another congeneric species, T. halophila. These microsatellite markers will be useful for investigating population genetics and adaptive evolution of this species and morphological divergence between and it and the closely related species.     

PERMANENT GENETIC RESOURCES: Twelve new microsatellite markers for the Chinese shrimp Fenneropenaeus chinensis

Twelve new microsatellite markers were isolated by sequencing random clones from a genomic library of Fenneropenaeus chinensis. The number of alleles per locus ranged from five to 15. The polymorphism information content ranged from 0.568 to 0.898, and observed and expected heterozygosities from 0.344 to 0.882 and from 0.691 to 0.915, respectively. All loci except one conformed to Hardy-Weinberg equilibrium. These markers, described here for Chinese shrimp, will be further used to analyse the species' population genetics.     

Development and characterization of microsatellite markers in Populus euphratica (Populaceae)

In this study, we developed 12 microsatellite loci for Populus euphratica and checked their variability in 27 individuals. The number of alleles for 12 loci ranged from five to nine, the observed and expected heterozygosities ranged from 0.32 to 0.48 and from 0.53 to 0.67. Frequencies of null alleles of all loci are not significantly greater than zero. None of the loci showed significant deviation from Hardy-Weinberg equilibrium. No significant linkage disequilibrium was observed between pairs of studied loci. These markers are useful in studies of population genetic structure of P. euphratica.     

UCP-2 and UCP-3 proteins are differentially regulated in pancreatic beta-cells

Background

Increased uncoupling protein-2 (UCP-2) expression has been associated with impaired insulin secretion, whereas UCP-3 protein levels are decreased in the skeleton muscle of type-2 diabetic subjects. In the present studies we hypothesize an opposing effect of glucose on the regulation of UCP-2 and UCP-3 in pancreatic islets.

Methodology

Dominant negative UCP-2 and wild type UCP-3 adenoviruses were generated, and insulin release by transduced human islets was measured. UCP-2 and UCP-3 mRNA levels were determined using quantitative PCR. UCP-2 and UCP-3 protein expression was investigated in human islets cultured in the presence of different glucose concentrations. Human pancreatic sections were analyzed for subcellular localization of UCP-3 using immunohistochemistry.

Principal Findings

Dominant negative UCP-2 expression in human islets increased insulin secretion compared to control islets (p<0.05). UCP-3 mRNA is expressed in human islets, but the relative abundance of UCP-2 mRNA was 8.1-fold higher (p<0.05). Immunohistochemical analysis confirmed co-localization of UCP-3 protein with mitochondria in human beta-cells. UCP-2 protein expression in human islets was increased ∼2-fold after high glucose exposure, whereas UCP-3 protein expression was decreased by ∼40% (p<0.05). UCP-3 overexpression improved glucose-stimulated insulin secretion.

Conclusions

UCP-2 and UCP-3 may have distinct roles in regulating beta-cell function. Increased expression of UCP-2 and decreased expression of UCP-3 in humans with chronic hyperglycemia may contribute to impaired glucose-stimulated insulin secretion. These data imply that mechanisms that suppress UCP-2 or mechanisms that increase UCP-3 expression and/or function are potential therapeutic targets to offset defects of insulin secretion in humans with type-2 diabetes.     

ASAP3 is a focal adhesion-associated Arf GAP that functions in cell migration and invasion

ASAP3, an Arf GTPase-activating protein previously called DDEFL1 and ACAP4, has been implicated in the pathogenesis of hepatocellular carcinoma. We have examined in vitro and in vivo functions of ASAP3 and compared it to the related Arf GAP ASAP1 that has also been implicated in oncogenesis. ASAP3 was biochemically similar to ASAP1: the pleckstrin homology domain affected function of the catalytic domain by more than 100-fold; catalysis was stimulated by phosphatidylinositol 4,5-bisphosphate; and Arf1, Arf5, and Arf6 were used as substrates in vitro. Like ASAP1, ASAP3 associated with focal adhesions and circular dorsal ruffles. Different than ASAP1, ASAP3 did not localize to invadopodia or podosomes. Cells, derived from a mammary carcinoma and from a glioblastoma, with reduced ASAP3 expression had fewer actin stress fiber, reduced levels of phosphomyosin, and migrated more slowly than control cells. Reducing ASAP3 expression also slowed invasion of mammary carcinoma cells. In contrast, reduction of ASAP1 expression had no effect on migration or invasion. We propose that ASAP3 functions nonredundantly with ASAP1 to control cell movement and may have a role in cancer cell invasion. In comparing ASAP1 and ASAP3, we also found that invadopodia are dispensable for the invasive behavior of cells derived from a mammary carcinoma.     

Use of activated carbon coated with bentonite for increasing the sensitivity of pcr detection of Escherichia coli O157:H7 in Canadian oyster (Crassostrea gigas) tissue

A novel method for directly increasing the recovery of Escherichia coli O157:H7 and efficiently eliminating PCR inhibitors in oyster tissue without preenrichment was developed with the use of activated carbon coated with bentonite. The recovery of E. coli O157:H7 was significantly affected by the amount of bentonite used to coat the activated charcoal and the pH value of sample preparations. When 4.2 g of activated carbon were coated with 0.4 g of bentonite and seeded oyster samples were adjusted to a pH of 5.0, a high recovery of E. coli O157:H7 (91.6+/-4.4%) was obtained. Activated carbon, coated with bentonite, allowed the PCR detection of 1.5 x 10(2) CFU/g of oyster tissue which was equivalent to 30 genomic targets per PCR reaction. Without the use of activated carbon coated with bentonite, the minimum level of detection was 1.5 x 10(5) CFU/g of oyster tissue, which is equivalent to 3.0 x 10(4) genomic targets per PCR reaction. Three commercial DNA purification systems were used for comparison. The limit of detection with the Wizard DNA Clean-Up System and the Chelex(R)100 Resin was 1.5 x 10(3) CFU/g of oyster tissue which was equivalent to 3.0 x 10(2) CFU/PCR reaction. The QIAamp DNA Mini Kit resulted in a detection limit of 5 x 10(2) CFU/g of oyster tissue which was equivalent to 5 x 10(2) genomic targets per PCR reaction. The use of activated carbon coated with bentonite is an inexpensive method for removal of PCR inhibitors from tissue samples prior to the release of DNA from target cells resulting in relatively low numbers of target cells detected without enrichment.