Influence of size and level of satiation on prey handling time in Channa striata (Bloch)

Channa striata fry (100 ± 20 mg) and fingerlings (2 ± 0.2 g) were offered mosquito larvae as prey and the adults (75 ± 5 g) small fishes. The size of the fish was directly related to satiation time and inversely related to satiation amount. The influence of satiation levels on handling time, showed an increase to almost eight-fold in fry and fingerlings and about two-fold in adults. The study also revealed the role played by the young of C. striata in mosquito control. With the increase in size of the fish the preference for mosquito larvae was seen to decrease. The air breathing habit and hence its ability to survive in polluted and oxygen-depleted waters makes it a suitable candidate as a fish for mosquito control.     

PRASINOPHYTES FORM INDEPENDENT LINEAGES WITHIN THE CHLOROPHYTA: EVIDENCE FROM RIBOSOMAL RNA SEQUENCE COMPARISONS1

Complete nuclear-encoded small-subunit ribosomal RNA (rRNA) sequences were determined from Nephroselmis olivacea Stein, Pseudoscourfieldia marina (Throndsen) Manton, Scherffelia dubia (Perty) Pascher, and Tetraselmis striata Butcher (Chlorophyta) to investigate the evolutionary position of these scaly green flagellates. Results of neighbor-joining and maximum parsimony phylogenetic analyses demonstrate at least two independent prasinophyte lineages defined by N. olivacea/P. marina and S. dubia/T. striata, which together with the Chlorophyceae, Pleurastrophyceae, and Ulvophyceae form a monophyletic group. Within this assemblage, N. olivacea and P. marina represent an early-diverging lineage that is evolutionarily distinct from the later-diverging S. dubia/T. striata clade. The branch point of the S. dubia/T. striata clade precedes the near-simultaneous radiation of the Chlorophyceae, Ulvophyceae, and Microthamniales. Though interrelationships between these three latter groups of algae are not resolved, the phylogenetic analyses demonstrate that the Prasinophyceae (sensu Moestrup and Throndsen) and the Pleurastrophyceae (sensu Mattox and Stewart) are not monophyletic classes.     

Dyakia bioluminescence—1. Bioluminescence and fluorescence spectra of the land snail,D. striata

The luminescent land snail Dyakia striata displayed a bioluminescence spectrum with a maximum wavelength of 515 nm. A green fluorescent substance extracted from the photogenic organ of an adult snail had a similar wavelength maximum but its fluorescence spectrum differed from that of flavin chromophore substances involved in light emission in some other luminescent organisms.     

Studies on the Changes of Cell Ultrastructure in the Course of Seed Germination of Bletilla striata Under Fungus Infection Conditions

Aided by the techniques of ultrathin section and electron microscopy, the changes of cell ultrastructure of seed germination of Bletilla striata was investigated. It was found that the seeds of B. striata were germinated easily among Orchidaceae, the large thin-wall cells of embryo contained a great amount of starch and lipid materials which were nutrients of seed germination. The differentiation and growth of the nutritive organ of B. striata would be accelerated after fungus infection. Fungus could penetrate seed coat in cell interstice, invaded, embryo through suspensor, and interspersed in several layers of embryonic ceils. Cytoplasm and organelles of embryo would disappear after the cells infected by fungus, and then endocytic plasmalemma produces some sacs enclosing and digesting hyphae. The hyphae with its tip inflation, relying on expansion-pressure of its cytoplasm, could penetrate cell wall of embryo. In addition, after invasion hyphae wall was significantly thickened by the deposition of the embryonic cytoplasm. In the end, the hyphae would be wholly collapsed and its degradated materials were used as nutrient for germination. The cells without penetration' by hyphae show vigrous metabolism activity in protocorms.     

Update on Wnt signaling in bone cell biology and bone disease

For more than a decade, Wnt signaling pathways have been the focus of intense research activity in bone biology laboratories because of their importance in skeletal development, bone mass maintenance, and therapeutic potential for regenerative medicine. It is evident that even subtle alterations in the intensity, amplitude, location, and duration of Wnt signaling pathways affects skeletal development, as well as bone remodeling, regeneration, and repair during a lifespan. Here we review recent advances and discrepancies in how Wnt/Lrp5 signaling regulates osteoblasts and osteocytes, introduce new players in Wnt signaling pathways that have important roles in bone development, discuss emerging areas such as the role of Wnt signaling in osteoclastogenesis, and summarize progress made in translating basic studies to clinical therapeutics and diagnostics centered around inhibiting Wnt pathway antagonists, such as sclerostin, Dkk1 and Sfrp1. Emphasis is placed on the plethora of genetic studies in mouse models and genome wide association studies that reveal the requirement for and crucial roles of Wnt pathway components during skeletal development and disease.     

美洲黑石斑鱼消化道的形态结构

采用解剖和光镜技术观察了美洲黑石斑鱼消化道的形态及组织学结构。消化道由口咽腔、食道、胃、肠构成。口咽腔较大,具颌齿、腭齿及犁齿;舌由基舌骨突出部分覆盖粘膜构成。食道、胃及肠均由粘膜层、粘膜下层、肌层及外膜构成。食道粘膜层绒毛分柱状上皮区及扁平上皮区,扁平上皮区表面为杯状细胞层;食道粘膜下层中有食道腺。胃呈V形,由贲门部、胃体部及幽门部组成,胃壁粘膜层上皮为单层柱状上皮,胃腺位于贲门部与胃体部的固有层中。肠细长,呈S型,由前、中、后肠构成,粘膜层向肠腔突起形成肠绒毛,粘膜上皮为单层柱状上皮,上皮游离面有微绒毛密集排列而成的纹状缘,上皮中含有杯状细胞,且杯状细胞的数量从前向后呈递减趋势;肠长/体长约为1.6。胃与小肠相接处有3对指状幽门盲囊,幽门盲囊的组织学结构与肠相同。     

Box-Benhnken响应面法优化白及愈伤组织的增殖培养基配方

为了提高白及组培过程中愈伤的增殖系数,以白及种子为外植体,利用响应面法对诱导愈伤的增殖培养基中的激素水平进行优化。在添加不同浓度的6-BA（6-苄氨基嘌呤）和2,4-D（2,4-二氯苯氧乙酸）的正交试验诱导愈伤基础上,根据Box-Benhnken（BBD）试验设计原理,采用三因素三水平的方法对3个激素的不同浓度水平进行组合实验。结果显示,通过回归模型分析获得增殖诱导的最佳培养基为MS+0.801 mg/L 6-BA（6-苄氨基嘌呤）+1.192 mg/L 2,4-D（2,4-二氯苯氧乙酸）+0.724 mg/L NAA（萘乙酸）。以优化后培养基进行愈伤组织继代发现其增殖系数为6.154 2,为理论预测值的99.74%。利用响应面法对愈伤组织增殖培养基进行优化,为以愈伤组织为研究材料的细胞悬浮培养、遗传转化、种苗快繁等研究奠定了基础。     

雌百灵端脑新生神经前体细胞的产生和分布并与白腰文鸟的比较

用BrdU标记DNA的ABC免疫细胞化学方法,观察雌性蒙古百灵端脑神经前体细胞的产生和分布特点,并与白腰文鸟作比较。结果如下:1.在百灵和白腰文鸟胸肌注射BrdU短时程组(存活1天),在端脑室带区外侧壁(LVZ)有大量的标记细胞,新生神经细胞起源于端脑室带区(VZ)中的增殖细胞层,并在纹状体腹侧的VZ形成标记细胞增殖热点,如在百灵和白腰文鸟靠近中缝线处的外侧纹状体(LSt)与内侧纹状体(MSt)腹侧的LVZ形成标记最多的‘第1增殖热点’区;在靠近中缝线处LVZ的头端形成密集的新生标记细胞,形成‘第2增殖热点’区;在百灵LSt尾端的LVZ标记细胞形成‘第3增殖热点’,但白腰文鸟此脑区的标记细胞较少。2.在百灵胸肌注射BrdU长时程组中5天起,大量的LVZ的标记细胞开始迁移,存活5-30天期间在高级发声中枢(HVc)和高位发声运动中枢-古纹状体栎核(RA)有新生标记细胞,在端脑靠近LVZ的区域有较多的标记细胞。但在雌性白腰文鸟胸肌注射BrdU存活30天期间,在HVC、RA内未见到标记细胞。结果提示雌百灵端脑HVc和RA不断地产生新生神经细胞,这可能与雌性需要不断地感知、识别雄百灵鸣唱的新语句有关,而白腰文鸟不需要这种功能。