The effect of plant growth regulators, nitric oxide, nitrate, nitrite and light on the germination of dimorphic seeds of Suaeda salsa under saline conditions

Suaeda salsa, a leaf succulent shrub in the family Chenopodiaceae, is one of the most important halophytes in China. Suaeda salsa produces dimorphic seeds (soft brown seeds and hard black seeds). Seeds of S. salsa were collected from the coastal salt flats near Huanghua City, China. Experiments were conducted to determine the salinity-alleviating effect of plant growth regulators, nitric oxide, nitrate, nitrite and light on the germination of dimorphic seeds of S. salsa. Brown seeds had a higher germination rate than black seeds in all experiments. Black seeds were more sensitive to salt in the absence of light in comparison to brown seeds. Brown seeds absorbed water more quickly in comparison to black seeds and were found to be more tolerant of salt stress. Our results showed that 1-aminocyclopropane-1-carboxylate (ACC, the immediate precursor of ethylene), nitrite, GA₄ and BA improved seed germination in the presence of salt. However, nitrate, GA₁, GA₃ failed to alleviate salt stress. ABA inhibited seed germination and seedling growth. Possible mechanisms involved in the alleviation of salt stress in S. salsa seeds and the ecological adaptation of the seeds to the environment are discussed.     

The Sec14 homology domain regulates the cellular distribution and transforming activity of the Rho-specific guanine nucleotide exchange factor Dbs

Dbs is a Rho-specific guanine nucleotide exchange factor that was identified in a screen for proteins whose overexpression cause deregulated growth in murine fibroblasts. Dbs contains multiple recognizable motifs including a centrally located Rho-specific guanine nucleotide exchange factor domain, a COOH-terminal Src homology 3 domain, two spectrin-like repeats, and a recently identified NH(2)-terminal Sec14 homology domain. The transforming potential of Dbs is substantially activated by the removal of inhibitory sequences that lie outside of the core catalytic sequences, and in this current study we mapped this inhibition to the Sec14 domain. Surprisingly removal of the NH(2) terminus did not alter the catalytic activity of Dbs in vivo but rather altered its subcellular distribution. Whereas full-length Dbs was distributed primarily in a perinuclear structure that coincides with a marker for the Golgi apparatus, removal of the Sec14 domain was associated with translocation of Dbs to the cell periphery where it accumulated within membrane ruffles and lamellipodia. However, translocation of Dbs and the concomitant changes in the actin cytoskeleton were not sufficient to fully activate Dbs transformation. The Sec14 domain also forms intramolecular contacts with the pleckstrin homology domain, and these contacts must also be relieved to achieve full transforming activity. Collectively these observations suggest that the Sec14 domain regulates Dbs transformation through at least two distinct mechanisms, neither of which appears to directly influence the in vivo exchange activity of the protein.     

甲型H1N1流感病毒血凝素蛋白单抗杂交瘤细胞株的制备与初步鉴定

目的:建立具有高特异、高效价的甲型H1N1流感病毒血凝素蛋白(HA)单抗的杂交瘤细胞株。方法:以纯化的昆虫杆状病毒表达的甲型H1N1流感病毒HA蛋白为免疫原免疫BALB/c小鼠,取脾细胞与Sp2/0小鼠骨髓瘤细胞融合,通过有限稀释法筛选阳性克隆,经ELISA和Western blot分析单抗的特性和特异性。结果:获得6株甲型H1N1流感HA抗原特异单克隆抗体杂交瘤细胞株,抗原肽库ELISA检测结果表明其中3株(1E12,3F12,1C11)单抗只与甲型H1N1流感HA抗原肽库反应,不与H5N1病毒HA抗原肽库反应;Western blot分析表明,单抗1B3只特异识别甲型H1N1流感HA抗原,而与其他季节性甲流病毒(H1,H3)及人禽流感H5N1病毒不反应。结论:所获杂交瘤细胞株特异性强,效价高,分泌抗体性能稳定,为分析甲型H1N1流感病毒抗原性位点、建立诊断试剂奠定了基础。     

人胎盘滋养层细胞原代的体外培养与改进

目的:建立与改进纯度较高的适于实验研究的人绒毛膜滋养层细胞。方法:采用胰蛋白酶消化法消化人正常妊娠6～8周胎盘组织,以35%、45%2个Percoll密度梯度进行分离纯化,并用免疫组化及透射电镜等技术对其生物学特性、细胞内部结构进行观察。结果:胎盘组织中滋养层细胞角蛋白染色阳性,血管内皮细胞及基质成分波形蛋白染色阳性,经该法分离纯化的细胞角蛋白染色阳性者(滋养层细胞)占90%以上,透射电镜观察示所获细胞有典型滋养层细胞结构。结论:该法简便易行,可获得合乎实验要求的人滋养层细胞,可供后续实验研究。     

近岸污染指示半知菌灰黄青霉(Penicillium griseo fulvum)的分子检测

【目的】通过分子方法检测近海污染环境优势种灰黄青霉,并为由此而推断污染程度做准备。【方法】根据GenBank中青霉属不同种和相近属种的ITS序列差异和灰黄青霉特有的IAO序列,设计了污染区优势种灰黄青霉的特异性引物AS1/RS4和IAO1/IAO2,建立相应的特异探针检测体系。通过PCR和套式PCR技术,分析比较两对特异序列检测灰黄青霉的差异。【结果】建立的分子检测体系可以排除其它近似或相关菌株干扰,从环境中扩增到目的基因片段。利用引物AS1/RS4作为核酸探针,通过套式PCR菌株DNA的检测灵敏度可达到10fg/μL,当仅有10个数量级分生孢子时即可检测出,从沉积物中检测灵敏度为102个数量级孢子/0.25g。特异酶基因IAO1/IAO2检测灵敏度较前者稍低。【结论】利用特异序列作为探针检测污染环境优势种灰黄青霉的方法可行,在一定范围内,灰黄青霉的出现频率及数量对污染程度有较好的指示作用。     

Towards precise classification of cancers based on robust gene functional expression profiles

Background

Despite the continuous production of genome sequence for a number of organisms, reliable, comprehensive, and cost effective gene prediction remains problematic. This is particularly true for genomes for which there is not a large collection of known gene sequences, such as the recently published chicken genome. We used the chicken sequence to test comparative and homology-based gene-finding methods followed by experimental validation as an effective genome annotation method.

Results

We performed experimental evaluation by RT-PCR of three different computational gene finders, Ensembl, SGP2 and TWINSCAN, applied to the chicken genome. A Venn diagram was computed and each component of it was evaluated. The results showed that de novo comparative methods can identify up to about 700 chicken genes with no previous evidence of expression, and can correctly extend about 40% of homology-based predictions at the 5' end.

Conclusions

De novo comparative gene prediction followed by experimental verification is effective at enhancing the annotation of the newly sequenced genomes provided by standard homology-based methods.     

The induction of trehalose and glycerol in Saccharomyces cerevisiae in response to various stresses

Trehalose and glycerol have been implicated as potential stress protectants that accumulate in yeasts during various stress conditions. We investigated the levels of glycerol and trehalose and the expression profiles of genes involved in their metabolism to determine their involvement in the response of Saccharomyces cerevisiae XQ1 to thermal, sorbitol and ethanol stresses. The results showed that the genes involved in the synthesis and degradation of trehalose and glycerol were stress induced, and that trehalose and glycerol were synthesized simultaneously during the initial stages (a sensitive response period) of diverse stress treatments. Trehalose accumulated markedly under heat treatment, but not under sorbitol or ethanol stress, whereas glycerol accumulated strikingly under sorbitol stress conditions. Interestingly, extracellular trehalose seemed to be involved in protecting cells from damage under unfavorable conditions. Moreover, our results suggest that the stress-activated futile ATP cycles of trehalose and glycerol turnover are of general importance during cellular stress adaptation.     

Architecture and function of the lophophore in the problematic brachiopod Heliomedusa orienta (Early Cambrian, South China)

The detailed structure of the lophophore is a key diagnostic character in the definition of higher brachiopod taxa. The problematic Heliomedusa orienta Sun and Hou, from the Lower Cambrian Chengjiang Lagerstätte of Yunnan, southwestern China, has a well-preserved lophophore, which is unlike that of any known extant or extinct brachiopods. Based on a comparative study of lophophore disposition in H. orienta and the extant discinid Pelagodiscus atlanticus, the in- and excurrent pattern and shell orientation of H. orienta are described and discussed. Reconstructions of lophophore shape and function are based on numerous specimens and comparison with P. atlanticus. The lophophore is composed of a pair of lophophoral arms that freely arch posteriorly rather than coiling anteriorly as commonly seen in fossil and recent lingulids. The lophophore is attached to the dorsal lobe of the mantle; it has neither calcareous nor chitinous supporting structures, and is disposed symmetrically on either side of the valve midline. The mouth can be inferred to be located at the base of the two brachial tubes, slightly posterior to the anterodorsal projection of the body wall. The lophophoral arms bear laterofrontal tentacles with a double row of cilia along their lateral edge, as in extant lingulid brachiopods. The main brachial axes are also ciliated, which presumably facilitated transport of mucous-bound nutrient particles to the mouth. The unique organization of the lophophore in Heliomedusa is not like any known fossil and living brachiopods. This clearly demonstrates that H. orienta is not a member of any crown group. It is here considered as a member of the brachiopod stem group, which challenges recent interpretations of a close discinid affinity.     

Synthesis, structures and DNA binding of ternary transition metal complexes M(II)L with the 2,2′-bipyridylamine (L = p-aminobenzenecarboxylic acid, M = Ni, Cu and Zn)

New ternary transition metal complexes of formulations [Ni(bpa)(p-AB)Cl]_n · 3nH₂O (bpa = 2,2′-bipyridylamine, p-AB = aminobenzenecarboxylic acid) (1), [Cu(bpa)(p-AB)Cl] · H₂O (2), [Zn(bpa)(p-AB)₂] · H₂O (3) are prepared, their structural features are characterized by crystal structural studies, and their DNA binding propensity has been evaluated by fluorescence and viscosity method. In complex 2 and 3, both bpa and p-AB act as the bidentate N and O-donor ligand, respectively. While in complex 1, p-AB acts as a rare tridentate ligand. In the packing pattern of each complex, π-π interaction in their solid state is also described. The complexes show the competitive inhibition of ethidium binding to DNA, and the DNA binding propensity can be reflected as the relative order: 1 > 2 > 3.