Chromosomal assignment of two putative canine keratin gene clusters

Mutations in keratin genes account for a number of inherited keratodermas in humans. The groups of basic and acidic keratin genes are clustered on human chromosomes 12 and 17, respectively. The present authors have assigned the two putative keratin gene clusters to canine chromosomes using canine cosmid clones. Successful fluorescence in situ hybridization mapped the putative cluster of canine acidic genes to dog chromosome 20 and the putative cluster of basic keratin genes to a small autosome not yet included in the partial canine standard karyotype.     

Effects of trichomes on the behavior and distribution of Platyprepia virginalis caterpillars

Trichomes are an important physical resistance mechanism of plants, as they reduce insect herbivore movement, feeding, and digestion. However, we know little about how trichomes influence herbivore distributions and populations. We conducted laboratory and field experiments to evaluate the preferences of Platyprepia virginalis (Boisduval) (Lepidoptera: Arctiidae) caterpillars to natural and manipulated densities of trichomes on their primary food, Lupinus arboreus Sims (Fabaceae). We then conducted field surveys to determine whether variation in trichome density among lupine bushes affected caterpillar spatial distribution on the landscape. Platyprepia virginalis caterpillars preferred lupine leaves with fewer trichomes in choice and no‐choice experiments. In the field, caterpillar feeding damage was found more often on leaves with fewer trichomes. These preferences scaled up to the level of bushes in the landscape such that more caterpillars were found on bushes with lower trichome densities than on bushes with higher trichome densities. This is one of few studies to show the potential for trichome density to influence herbivore population size and distribution in a natural system at a landscape level. The results are consistent with trichomes functioning as a resistance mechanism with consequences for herbivore choice, performance, and distribution.     

Habitat and abundance of Balitoridae in small rivers of central Thailand

Balitorids were collected, by electrofishing, from small rivers across central Thailand between October 2000 and March 2004. Total balitorid abundance for the 18 species averaged 3·8% of the cumulative total for all fishes. Balitorid species numbers and abundance varied directly with elevation to c. 400 m, substratum particle size and ambient silica concentration. Species numbers at stations were modest and few species were widely distributed. Species associations related significantly with elevation, temperature and ambient concentrations of dissolved oxygen and silica. Turbidity was also significant but probably an artefact. Habitat separation clearly occurs among some balitorids, particularly the less common species, and probably represents species-specific direct and indirect habitat effects. The more common balitorid species tended to occur in similar habitats where the significant factors approximated average values. For these species, coexistence is suggested to occur through food resource sharing possibly facilitated through adaptations. Balitorid distributions in low-order rivers are attributed to the direct and indirect influences of the environment on energy available for the performance of essential activities.     

Influence of Thickeners on the Fragmentation of Fish Meat Sausage by Mastication

The influence of food thickeners (potato starch, guar gum, and xanthan gum and deionized water) on the breakdown of solid food was numerically analyzed, and an investigation was made into the cumulative size distribution of food fragments, textural properties, sensory evaluation and maximum transit velocity of a bolus in the pharynx.

The results suggest that evaluating the breakability into small pieces was easily influenced by the addition ratio of the dispersion medium. However, in respect of the destruction process for the solid body, each sample was more strongly affected by the type of the dispersion medium than by the addition ratio of this medium.

The destruction process was strongly influenced by the history of the breakdown caused by mastication when a liquid dispersion medium was added to the solid. However, when a high-viscosity sol was added to the solid, the destruction process was random and not affected by any history.     

Arm lengths and arm reaches: some interrelationships of structural and functional body dimensions

Structural measurements of the human body have for the most part been of little practical use as indicators of such functional body dimensions as arm reaches. These dimensions, which define the area around the body to which a person can reach given certain specified conditions and constraints are often critical for the design and layout of workspaces. However, they are relatively difficult and time-consuming to obtain, usually requiring specially constructed measuring systems for each differing design situation, as well as resurveys for each physically distinct population. An alternate approach, described here, investigates the interrelationships between these two classes of measurements with the aim of predicting functional reaches from structural body dimensions. In the present study traditional structural measurements and 117 functional arm reaches were obtained on 100 subjects. Correlations between the two types of measures are reported. Regression equations are presented which can predict functional arm reaches from two structural body dimensions on anthropometrically differing populations under a fixed set of workspace conditions.     

迷卡斗蟋鸣声的声学特征及其生物学意义

首次利用计算机技术对迷卡斗蟋Velarifictorusmicado (Saussure)的鸣声特征及其生物学意义进行了研究。结果表明 :迷卡斗蟋在不同性比条件下 ,鸣声的声学特征不同。雄性独处时发出召唤声 ;2只以上的雄性在一起时会发出警戒声、挑战声或胜利声 ;1雄 1雌在一起时会发出欢迎声、求爱声 ,如果雌性不理会雄性的求爱时则会发出一种催促声。利用计算机 ,除了对人们用耳辨别的 3种鸣声 (召唤声、求偶声和争斗声 )进行客观记录外 ,还可以对以前所称的“求偶声”和“争斗声”进行更细致地分析和比较。根据其生物学意义 ,作者首次将其鸣声分为 7种 ,并对这 7种鸣声在功率谱和时域两方面进行了比较 ,发现迷卡斗蟋在不同行为下有不同的鸣声特征 ,传递不同的信息。     

苏云金杆菌酪氨酸酶基因转化子黑色素的研究

苏云金杆菌(Bacillusthuringiensis,Bt)是使用广泛的杀虫细菌。将构建的含有嗜麦芽假单胞菌酪氨酸酶基因的重组质粒导入苏云金杆菌体内,使后者获得了稳定产生黑色素的能力。所产黑色素是无定形物质,在大多数有机和无机溶剂中溶解度低或不溶解,在碱性溶液中有较好的溶解性,在中性及弱酸性溶液中溶解度低,pH<4时沉淀;可用过氧化氢或次氯酸钠氧化,也能被银离子或硫化氢还原;含有天然物质中少见的自由基,并能清除由紫外线诱导产生的自由基;能吸收所有波长的光线,在紫外波长下吸收值最大,能有效地保护紫外辐射对蛋白质及DNA等生物大分子物质的损害,具有很强的抗辐射作用。使转化子抗辐射能力显著增强,杀虫活性稳定保持;能抵抗病毒的侵袭,生长旺盛;对畜禽安全。     

陕西黄土区不同施肥条件下农田土壤动物的群落组成和结构

为探明长期施肥与土壤动物群落之间的关系,于2001年6月至2002年10月,在陕西黄土区对不同施肥条件下的农田土壤动物类群的群落组成和结构进行了研究.在6种不同施肥处理的小区内,即对照组(不施肥,简称CK)、撂荒(不施肥、不耕作、不种植,简称ABAND)、施氮磷钾(简称NPK)、施氮磷钾+秸秆(简称SNPK)、施氮磷钾+有机肥(简称MNPK)和施1.5倍MNPK(简称1.5MNPK),两年4次共采集了72个定点土壤样品.采用手捡法和Cobb过筛法共获得农田土壤动物标本5495个,隶属6门11纲22目61科2亚科35属.结果显示6种施肥处理中,大型农田土壤动物的个体总数从多到少依次为SNPK＞1.5MNPK＞NPK＞ABAND＞MNPK＞CK,类群数依次是1.5MNPK＞NPK＞SNPK＞CK＞ABAND=MNPK.中小型农田土壤动物个体总数由多到少依次为1.5MNPK＞MNPK＞ABAND＞SNPK＞NPK＞CK,类群数依次是SNPK=MNPK＞CK=NPK=1.5MNPK＞ABAND.大型农田土壤动物个体数和类群数分布最多的分别是SNPK和1.5MNPK处理,而中小型农田土壤动物则分别是1.5MNPK和SNPK处理.表明农田土壤动物类群分布与施肥处理有关.农田土壤动物优势类群分布以施氮磷钾(NPK)小区最多,常见类群以对照组(CK)最多,极稀有类群以施1.5倍MNPK小区最多.群落相似性指数分析结果表明,在不同施肥处理之间,农田土壤动物的相似性系数一般较低,而其群落组成的异质性较高如大型土壤动物群落在撂荒地与其他施肥处理之间的相似性明显低于其他各施肥处理之间;而中小型土壤动物群落在对照小区与其他施肥之间的相似性指数明显低于其他各施肥处理之间,反映出不同施肥处理对土壤生态系统内部环境,进而对土壤动物群落产生的影响.     

Aspergillus sp.脂肪酶发酵条件优化及酶学性质的研究

作者为了得到一种热稳定性较好的脂肪酶新酶种,通过研究分离白极端环境的Aspergillus sp．的最佳产酶条件及其所产脂肪酶的酶学性质,得出了该菌产酶的最佳发酵条件为：以1％黄豆饼粉为氮源、0．2％玉米淀粉为碳源,1．5％橄榄油为诱导物,起始pH6．0左右。装量10mL（250mL三角瓶。摇瓶转速180r／min）、发酵时间为96h。在最佳发酵条件下可得最大发酵酶活36U/mL。Aspergillus sp．所产的脂肪酶的酶学性质是：最适pH为9．0,在pH5．0—10．0于20℃下放置24h后,残余酶活仍保持在起始酶活的90％以上;该酶的最适温度为50℃,50℃保温60min后仍保留70％以上的酶活。Aspergillus sp．所产脂肪酶的热稳定性较好。     

桃花水母

介绍了桃花水母的生活习性、形态、生理、分类、分布,讨论了桃花水母的研究意义及经济价值。