Selective localization of G protein γ5 subunit in the subventricular zone of the lateral ventricle and rostral migratory stream of the adult rat brain

G proteins play important roles in transmembrane signal transduction, and various isoforms of each subunit, alpha, beta and gamma, are highly expressed in the brain. The Ggamma5 subunit is a minor isoform in the adult brain, but we have previously shown it to be highly expressed in the proliferative region of the ventricular zone in the rat embryonic brain. We show here that Ggamma5 is also selectively localized in a proliferative region in the adult rat brain, including the subventricular zone of the lateral ventricle and rostral migratory stream. The Galphai2 subunit colocalized with Ggamma5 in these regions, the two subunits being present in neuronal precursors and ependymal cells but not in proliferating astrocytes. In addition, intense staining of Ggamma5 was seen in axons of the olfactory neurons, which are known to regenerate. These results suggest specific roles for Ggamma5 in precursor cells during neurogenesis so that this isoform might be a useful biological marker.     

Functional Role for Protein Kinase Cβ as a Regulator of Stress-Activated Protein Kinase Activation and Monocytic Differentiation of Myeloid Leukemia Cells

Human myeloid leukemia cells respond to 12-O-tetradecanoylphorbol-13-acetate (TPA) and other activators of protein kinase C (PKC) with induction of monocytic differentiation. The present studies demonstrated that treatment of U-937 and HL-60 myeloid leukemia cells with TPA, phorbol-12,13-dibutyrate, or bryostatin 1 was associated with the induction of stress-activated protein kinase (SAPK). In contrast, TPA-resistant TUR and HL-525 cell variants deficient in PKCβ failed to respond to activators of PKC with the induction of SAPK. A direct role for PKCβ in TPA-induced SAPK activity in TUR and HL-525 cells that stably express PKCβ was confirmed. We showed that TPA induced the association of PKCβ with MEK kinase 1 (MEKK-1), an upstream effector of the SAPK/ERK kinase 1 (SEK1)→SAPK cascade. The results also demonstrated that PKCβ phosphorylated and activated MEKK-1 in vitro. The functional role of MEKK-1 in TPA-induced SAPK activity was further supported by the demonstration that the expression of a dominant negative MEKK-1 mutant abrogated this response. These findings indicate that PKCβ activation is necessary for activation of the MEKK-1→SEK1→SAPK cascade in the TPA response of myeloid leukemia cells.     

Sister Chromatid Exchanges Are Mediated by Homologous Recombination in Vertebrate Cells

Sister chromatid exchange (SCE) frequency is a commonly used index of chromosomal stability in response to environmental or genetic mutagens. However, the mechanism generating cytologically detectable SCEs and, therefore, their prognostic value for chromosomal stability in mitotic cells remain unclear. We examined the role of the highly conserved homologous recombination (HR) pathway in SCE by measuring SCE levels in HR-defective vertebrate cells. Spontaneous and mitomycin C-induced SCE levels were significantly reduced for chicken DT40 B cells lacking the key HR genes RAD51 and RAD54 but not for nonhomologous DNA end-joining (NHEJ)-defective KU70(-/-) cells. As measured by targeted integration efficiency, reconstitution of HR activity by expression of a human RAD51 transgene restored SCE levels to normal, confirming that HR is the mechanism responsible for SCE. Our findings show that HR uses the nascent sister chromatid to repair potentially lethal DNA lesions accompanying replication, which might explain the lethality or tumorigenic potential associated with defects in HR or HR-associated proteins.     

The boundary-expressed EPIDERMAL PATTERNING FACTOR-LIKE2 gene encoding a signaling peptide promotes cotyledon growth during Arabidopsis thaliana embryogenesis

The shoot organ boundaries have important roles in plant growth and morphogenesis. It has been reported that a gene encoding a cysteine-rich secreted peptide of the EPIDERMAL PATTERNING FACTOR-LIKE (EPFL) family, EPFL2, is expressed in the boundary domain between the two cotyledon primordia of Arabidopsis thaliana embryo. However, its developmental functions remain unknown. This study aimed to analyze the role of EPFL2 during embryogenesis. We found that cotyledon growth was reduced in its loss-of-function mutants, and this phenotype was associated with the reduction of auxin response peaks at the tips of the primordia. The reduced cotyledon size of the mutant embryo recovered in germinating seedlings, indicating the presence of a factor that acted redundantly with EPFL2 to promote cotyledon growth in late embryogenesis. Our analysis suggests that the boundary domain between the cotyledon primordia acts as a signaling center that organizes auxin response peaks and promotes cotyledon growth.     

Cloning and expression of manganese superoxide dismutase of the silkworm, Bombyx mori by Bac-to-Bac/BmNPV Baculovirus expression system

Superoxide dismutase (SODs) are metalloenzymes that catalyze the dismutation of the superoxide anion to molecular oxygen and hydrogen peroxide and, thus, form a crucial part of the cellular antioxidant defense mechanism. In this paper, we used the total fat body RNA of silkworm, Bombyx mori L. to clone and sequence a 648-bp Mn-SOD cDNA fragment through RT-PCR. Furthermore, a newly established Bac-to-Bac/BmNPV Baculovirus expression system was used to overexpress the recombinant Mn-SOD enzyme in silkworm larvae. The hemolymph was collected from the infected larvae 96 h post-infection and subjected to a 12 % SDS-PAGE and Western blotting. A 18.0-kDa protein was visualized after rBacmid/BmNPV/SOD infection. The SOD enzyme activity was determined with a tetrazolium salt for detection of superoxide radicals generated by xanthine and xanthine oxidase and its peak appeared in 96 h post-infection with 2.7 times of the control larvae. The availability of large quantities of SOD that the silkworm provides should greatly facilitate the future research and testing of this protein for potential application in medicine.     

施用有机肥对侵蚀黑土玉米苗期根内生细菌多样性的影响

为了解根内生细菌群落结构在土壤侵蚀条件下的变化,明确有机肥施用对其多样性的影响,本研究采用LNA-PCR和454高通量测序技术相结合的方法对土壤表层剥离30 cm和施用有机肥处理的玉米苗期根内生细菌群落结构进行研究,以表层土没有剥离和单施化肥处理为对照.试验共获得37820条16S rDNA有效序列,主要分布在4个门35个纲214个属和782个OTU,其中,变形菌门、厚壁菌门、放线菌门和拟杆菌门为优势菌门,但不同样品各菌门分布比例存在差异.土壤侵蚀降低了玉米苗期根内生细菌群落多样性,但增施有机肥可以增加根内生细菌群落多样性,这种作用以表层土剥离30 cm处理表现得更为突出.     

Taxonomic and ecological profile of `green tide' species of Ulva (Ulvales,Chlorophyta) in central Philippines

Hydrobiologia - Ulva spp. are common in the intertidal zones of the Philippines, but, at certain times, could over-proliferate producing blooms or `green tide' in some protected bays. In Mactan...     

High-density Integrated Linkage Map Based on SSR Markers in Soybean

A well-saturated molecular linkage map is a prerequisite for modern plant breeding. Several genetic maps have been developed for soybean with various types of molecular markers. Simple sequence repeats (SSRs) are single-locus markers with high allelic variation and are widely applicable to different genotypes. We have now mapped 1810 SSR or sequence-tagged site markers in one or more of three recombinant inbred populations of soybean (the US cultivar ‘Jack’ × the Japanese cultivar ‘Fukuyutaka’, the Chinese cultivar ‘Peking’ × the Japanese cultivar ‘Akita’, and the Japanese cultivar ‘Misuzudaizu’ × the Chinese breeding line ‘Moshidou Gong 503’) and have aligned these markers with the 20 consensus linkage groups (LGs). The total length of the integrated linkage map was 2442.9 cM, and the average number of molecular markers was 90.5 (range of 70–114) for the 20 LGs. We examined allelic diversity for 1238 of the SSR markers among 23 soybean cultivars or lines and a wild accession. The number of alleles per locus ranged from 2 to 7, with an average of 2.8. Our high-density linkage map should facilitate ongoing and future genomic research such as analysis of quantitative trait loci and positional cloning in addition to marker-assisted selection in soybean breeding.Key words: EST-derived SSR marker, integrated linkage map, microsatellite marker, polymorphism information content     

水稻雌性不育材料FS－1胚囊败育的细胞学观察

以水稻雌性不育材料FS－1为试验材料,采用石蜡连续切片技术对FS－1及其亲本藤坂5号幼穗发育中期的胚囊进行观察。结果表明：（1）亲本的胚囊都能正常发育分化,成为功能健全的雌配子体,而FS－1的胚囊却普通发生败育,在胚囊原来的区域充满了胚囊残迹和解体的珠心细胞。（2）败育基本上发生在功能大孢子发生期,近合点端的大孢子和珠孔端的三个大孢子都发生解体,实验中未发现二核,四核或八核的败育胚囊,我们初步认为,FS－1胚囊败育发生在功能大孢发生期。