鮈亚科鱼类下咽骨和下咽齿的形态差异及其功能适应

采用双筒解剖镜观察和手工绘图的方法,研究鮈亚科鱼类39个代表种下咽骨和下咽齿的形态特征,分析鮈亚科鱼类下咽骨和下咽齿的形态差异及其功能适应。结果显示,鮈亚科鱼类的下咽骨可以分为粗壮型、中间型和狭长型3种形态类型;下咽齿可以分为圆锥型、臼齿型、粗壮侧扁型、侧扁型和极侧扁型5种形态类型。鮈亚科鱼类下咽骨和下咽齿间呈现出多种形态组合,并相互配合共同处理不同类型的食物。下咽骨和下咽齿的形态差异为鮈亚科鱼类摄食不同类型的食物、充分利用不同的生境资源在摄食器官多样性方面提供了保证。

东湖沉积物中微生物量与碳、氮、磷的相关性

对武汉东湖3个采样点柱状沉积物中总氮、总磷、总有机碳及微生物量的垂向分布进行了测定,并对生源要素与微生物量之间垂向分布的相关性进行了研究.结果表明,东湖柱状沉积物中总有机碳与总氮之间存在明显的同步变化趋势,其含量随着沉积物深度的增加而不断降低,处于纳污区的1号点的各种营养盐含量均显著高于其它各点.沉积物中的有机质有着明显的双重来源,1号点含有较高的陆源有机质成分,而远离排污口部分的2号和3号点的有机质来源则以水生生物为主.微生物量在沉积物表层最高,随着沉积物深度的增加而不断下降.微生物量与有机质含量之间存

海峡两岸淡水鱼类分布格局及其生物地理学意义

通过台湾大陆初级淡水鱼类区系的比较分析,将台湾与大陆间的淡水鱼类区系和组成归纳为3种生物地理分布格局:(1)台湾与大陆东南沿海诸水系的淡水鱼类有很高相似性;(2)台湾与东喜马拉雅具有一些相同的淡水鱼类分布;(3)包括台湾岛在内的太平洋西部岛链的淡水鱼类区系之间的相似度很低,这些岛屿与各自相邻大陆的淡水鱼类更相似.从历史生物地理学的角度看,这种分布格局的形成与台湾和大陆古地理、地质的变迁有关.简约分析(PAE)结果认为,以上格局可以用隔离分化的假说加以解释,进一步的研究将使用分子生物地理学方法和手段对海峡两

中华双腔吸虫精子的超微结构

利用透射电镜技术，研究了中华双腔吸虫（Ｄｉｃｒｏｃｏｅｌｉｕｍ　ｃｈｉｎｅｎｓｉｓ Ｔａｎｇ ｅｔ Ｔａｎｇ， １９７８）的精子结构，探讨了它与其他复殖吸虫间的异同。结果表明：本种的成熟精于为细线状，共分为头部、中部和尾部，具两根并生的、结构为９＋１的轴丝。细胞核的致密程度有区域上的变化，细胞质较多，电子密度高，具一个线粒体，在单轴丝区域未观察到异常二联管及外周微管。

显著车轮虫无性繁殖生物学研究

显著车轮虫无性繁殖过程中,其新齿环在分裂前期发生于旧齿环和辐线环之间;由细线状圆环分节以覆瓦式排列,其数目常为旧环的一倍,少数个体有增多。随着虫体发育,新环依次长出齿钩、锥体、齿棘。旧环则依齿钩、齿棘、锥体、齿钩柄的顺序消失;口沟、伸缩泡均在分裂前期分裂,各自形成两个新的口沟、伸缩泡;新辐线在子体发育初或中期才发生于新齿环外缘,总数为旧辐线的一倍。该虫无性繁殖以24小时为一周期。分裂前期需0.5—1小时;分裂期需1—3分钟。幼虫生长发育期需1.5—3小时。成虫生长成熟期需20—22小时。无论幼虫、童虫和成

四倍化草鱼细胞株的获得、特性和移核实验的初步试探

本文报道经过35次再培养的草鱼尾鳍细胞,用秋水仙素诱导后约有71％左右细胞四倍化(染色体加倍)。经过6次再培养以后四倍化细胞上升到78％左右,建立了四倍化的草鱼细胞株,命名为GOC(4)。 本文还报道了把GCC(4)细胞(核)移植到草鱼及泥鳅的去核未受精卵内,有80％的草鱼卵发育到囊胚。在总数为342个泥鳅的移核卵中有5个发育到肌肉效应期,1个发育到心跳期。

Identification and characterization of a novel gene differentially expressed in zebrafish cross-subfamily cloned embryos

m Background: Cross-species nuclear transfer has been shown to be a potent approach to retain the genetic viability of a certain species near extinction. However, most embryos produced by cross-species nuclear transfer were compromised because that they were unable to develop to later stages. Gene expression analysis of cross-species cloned embryos will yield new insights into the regulatory mechanisms involved in cross-species nuclear transfer and embryonic development. Results: A novel gene, K31, was identified as an up-regulated gene in fish cross-subfamily cloned embryos using SSH approach and RACE method. K31 complete cDNA sequence is 1106 base pairs (bp) in length, with a 342 bp open reading frame (ORF) encoding a putative protein of 113 amino acids (aa). Comparative analysis revealed no homologous known gene in zebrafish and other species database. K31 protein contains a putative transmembrane helix and five putative phosphorylation sites but without a signal peptide. Expression pattern analysis by real time RT-PCR and whole-mount in situ hybridization (WISH) shows that it has the characteristics of constitutively expressed gene. Sub-cellular localization assay shows that K31 protein can not penetrate the nuclei. Interestingly, over-expression of K31 gene can cause lethality in the epithelioma papulosum cyprinid (EPC) cells in cell culture, which gave hint to the inefficient reprogramming events occurred in cloned embryos. Conclusion: Taken together, our findings indicated that K31 gene is a novel gene differentially expressed in fish cross-subfamily cloned embryos and over-expression of K31 gene can cause lethality of cultured fish cells. To our knowledge, this is the first report on the determination of novel genes involved in nucleo-cytoplasmic interaction of fish cross-subfamily cloned embryos.

alr0117, a two-component histidine kinase gene, is involved in heterocyst development in Anabaena sp PCC 7120

Anabaena sp. PCC; 7120 was mutagenized by transposon Tn5-1087b, generating a mutant whose heterocysts lack the envelope polysaccharide layer. The transposon was located between nucleotides 342 and 343 of alr0117, a 918 bp gene encoding a histidine kinase for a two-component regulatory system. Complementation of the mutant with a DNA fragment containing alr0117 and targeted inactivation of the gene confirmed that alr0117 is involved in heterocyst development. RT-PCR showed that alr0117 was constitutively expressed in the presence or absence of a combined-nitrogen source. hepA and patB, the two genes turned on during wild-type heterocyst development, were no longer activated in an alr0117-null mutant. The two-component signal transduction system involving alr0117 may control the formation of the envelope polysaccharide layer and certain late events essential to the function of heterocysts.

适合于芯片集成的被动型铷原子频标

本发明公开了一种适合于芯片集成的被动型铷原子频标，包括量子系统、伺服电路、20MHz压控振荡器和第一2分频器;其中，量子系统由100MHz电离源、Rb87灯、Rb85滤光泡、谐振腔Rb87吸收泡以及光电检测电路构成;伺服电路由低噪声放大器、带通滤波器、缓冲器、模数转换器、控制器、数模转换器、比较器、锁相环电路、第二2分频器、DDS和混频器构成;其中锁相环电路包括342分频器、鉴频鉴相器、电荷泵、滤波器和6840MHz压控振荡器。利用本发明，极大的提高了被动型铷原子频标稳定性和相位噪声指标，降低了被动型铷原子频标的功耗，减小了被动型铷原子频标的重量和体积，便于被动型铷原子频标的芯片集成。

Effect of metal contact's reflection on the effective coupling coefficient of second-order DFB laser diodes

For a second-order DFB-LD, the presence of a metal contact layer can reduce I-st-order radiation. Part of the reflected power is redistributed into guided modes and results in a variation of the effective coupling coefficient kappa(eff). In this paper, we study the effect of the Au top contact's reflection on the kappa(eff) of 2(nd)-order DFB lasers. (C) 2004 Wiley Periodicals, Inc.

Photoluminescence of Mg-doped GaN grown by metalorganic chemical vapor deposition

Two Mg-doped GaN films with different doping concentrations were grown by a metalorganic chemical vapor deposition technique. Photoluminescence (PL) experiments were carried out to investigate the optical properties of these films. For highly Mg-doped GaN, the PL spectra at 10 K are composed of a blue luminescence (BL) band at 2.857 eV and two excitonic luminescence lines at 3.342 eV and 3.282 eV, in addition to a L2 phonon replica at 3.212 eV. The intensity of the L1 line decreases monotonously with an increase,in temperature. However, the intensity of the L2 line first slowly increases at first, and then decreases quickly with an increase in temperature. The two lines are attributed to bound excitonic emissions at extended defects. The BL band is most likely due to the transition from deep donor Mg-V-N complex to Mg shallow acceptor. From the temperature dependence of the luminescence peak intensity of the BL band, the activation energy of acceptor Mg was found to be 290 meV. (C) 2003 American Vacuum Society.

In situ doping of 3C-SiC grown on (0001) sapphire substrates by LPCVD

The heteroepitaxial growth of n-type and p-type 3C-SiC on (0001) sapphire substrates has been performed with a supply of SiH4+C2H4+H-2 system by introducing ammonia (NH3) and diborane (B2H6) precursors, respectively, into gas mixtures. Intentionally incorporated nitrogen impurity levels were affected by changing the Si/C ratio within the growth reactor. As an acceptor, boron can be added uniformly into the growing 3C-SiC epilayers. Nitrogen-doped 3C-SiC epilayers were n-type conduction, and boron-doped epilayers were p-type and probably heavily compensated.

New annealing processes and explanation for novel silicon pn junctions formed by proton implantation

Proton-implanted n-type Si wafers were annealed at 950 degrees C to achieve novel pn junctions. The novel pn junctions are explained by the combined use of four models. The background (e.g. oxygen impurity) of an Si wafer is suggested to play a key role in creating the novel pn junction.