褐云玛瑙螺的繁殖习性及其贝壳在胚后发育期的变化

褐云玛瑙螺(Achatina fulica Ferussac)又名花螺,为华南地区危害农作物的一种陆栖贝类。关于它的繁殖习性及其胚后发育问题的研究尚缺乏。作者近年来在从事褐云玛瑙螺的生态研究过程中,注意观察了它的繁殖习性及其胚后发育时外壳的变化,除在野外现场观察外,并采集标本回室内从事生殖器官、螺体测量及室内饲养观察,现将观察结果报导如后。 一、繁殖习性的观察 在广州地区褐云玛瑙螺的     

褐云玛瑙螺(Achatina fulica Férussac)受精位置的探讨

对于褐云玛瑙螺的形态及某些器官的机能,梁羡园(1959)曾进行过研究。但是对于褐云玛瑙螺的受精位置问题,还存在不同的意见。梁羡园认为褐云玛瑙螺的受精位置十分可能是在蛋白腺基部的盲囊形受精室内,同时提出还需今后进一步的探讨。张、齐钟彦(1961)在贝类学纲要一书中,引述了梁羡园的意见。江静波(1959)在解剖褐云玛瑙螺时发现两性管上有一囊,囊中充满了精子。有时在输卵管内充满许多有壳的卵子(就是说这些卵子已受精),同时在两性管上的囊内也充满了精子。这些精子很可能是来自另一个螺体,认为受精作用应是在两性管上的囊内进行。因此,称这囊为受精囊。我们认为,在这方面进一步深入研究,既可给教师参考解决教学上在这方面的疑难问题,更可为褐云玛瑙螺生殖发育的深入研究打下基础。     

外来物种褐云玛瑙螺(非洲大蜗牛)

褐云玛瑙螺(Achatina fulica Ferussac,1822),又称非洲大蜗牛．原产于东非沿岸桑给巴尔、奔巴岛一带。据报道,现已知全世界玛瑙螺科Achatinidae共计有23属和亚属,其中玛瑙螺属Achatina有80种和亚种,在我国仅此1种．主要分布于我国福建南部、珠江三角洲、雷州半岛、海南岛、广西南部及云南南部等地区。这一外来物种给当地农业、园艺等经济作物造成很大的危害。     

有害植物孪花蟛蜞菊扩张对西沙岛屿陆生软体动物的影响

有害植物孪花蟛蜞菊(Wedelia biflora)的扩张对我国西沙群岛原生植物群落结构和功能产生了深刻影响, 但陆生软体动物如何响应该扩张却未见报道。本文调查了西沙群岛永兴岛孪花蟛蜞菊不同扩张程度下褐云玛瑙螺(Achatina fulica)、钻头螺科、坚齿螺科和拟阿勇蛞蝓科等主要陆生软体动物的残体分布情况, 测定了残体的分布密度和壳高、壳宽、壳重等可量化性状指标, 研究了孪花蟛蜞菊扩张对陆生软体动物种群的影响。结果表明: (1)随孪花蟛蜞菊扩张程度增加, 钻头螺科和褐云玛瑙螺的种群密度增加, 坚齿螺科种群密度减小, 拟阿勇蛞蝓科种群密度出现先增加后减少的趋势; (2)陆生软体动物类群的体型分布频率随孪花蟛蜞菊扩张呈现不同的变化趋势, 褐云玛瑙螺较小个体数量增加, 其他陆生软体动物体型分布变化不明显或较大体型残体分布增加; (3)孪花蟛蜞菊扩张对褐云玛瑙螺体型特征产生抑制作用, 褐云玛瑙螺主要采用r策略来响应有害植物扩张的影响。综上, 有害植物孪花蟛蜞菊在热带珊瑚岛屿植被中的扩张改变了陆生软体动物的形态、密度与种群结构, 不同的软体生物类群表现出不同响应策略, 在海岛有害生物的综合防治过程中应该引起足够重视。     

褐云玛瑙螺的生态观察及其对碱度的迥避性生理反应

为开辟家畜、家禽的动物性蛋白饲料的来源,开展褐云玛瑙螺的人工养殖已提到日程上来。饲养褐云玛瑙螺要圈起来养,以形成一个完整的生物生化物质循环(如图),既可综合利用,又可减少对作物的危害。     

褐云玛瑙螺（Achatina fulica）北方冬季室内饲养的探讨

作者在实验室控制温度、湿度等条件下,以麦麸、玉米面粉及鸭跖草为饲料对褐云玛瑙螺进行室内饲养。实验表明：在温度２６℃,相对湿度８０￣９０％的条件下,每个成螺平均产卵２３４．４粒;卵孵化率为９０．７２％;幼螺成活率为９４．３％;从初孵幼螺长至体重为３５．６ｇ的成螺需１９６天／２６℃,１７３天／２８℃;从２克重的幼螺长至３５．６克重的成螺,每个螺平均累积取食混合饲料２２９．７ｇ。饲养密度会影响螺的生长,     

蜗牛电栏的初步试验

大蜗牛(Helix)是西欧许多国家尤其是法国的重要食品,褐云玛瑙螺(Achatina fulica)又称非洲蜗牛亦有很高食用价值。目前国际上蜗牛的消费量很大,已供不应求,因此在一些国家和地区已开始了蜗牛的人工养殖。养殖方法简单易行,但防逃问题却是关键一环,因为如让其逃入农园则会破坏农作物造成灾害。国内曾有人试验用柴灰等高碱(pH11.5)三合土围墙拦养,似有一定效果,但在生产上应用仍很不便。故我们用褐云玛瑙螺试以电栏,获得初步效果,现简报如下:     

米曲霉两株营养缺陷型原生质体的形成和再生的条件实验*

采用1%溶壁酶加1%玛瑙螺酶(褐云玛瑙螺消化液的冷冻干粉)的混合酶,自米曲霉(Aspergillus oryzae)的两株营养缺陷型中获得了大量的原生质体,并比较了渗透压稳定剂、温度、菌丝体的培养基成分等因素对原生质体形成和再生的作用。无机盐类稳定剂(NaCl、KCl)获得了高产量的原生质体,而有机类(蔗糖、甘露醇、山梨醇)做为稳定剂不甚理想。对120和720菌株的原生质体在高渗再生培养基上进行再生试验,再生率分别为52%和65%。     

米曲霉两株营养缺陷型原生质体的形成和再生的条件实验

采用1%溶壁酶加1%玛瑙螺酶(褐云玛瑙螺消化液的冷冻干粉)的混合酶,自米曲霉(Aspergillus oryzae)的两株营养缺陷型中获得了大量的原生质体,并比较了渗透压稳定剂、温度、菌丝体的培养基成分等因素对原生质体形成和再生的作用。无机盐类稳定剂(NaCl、KCl)获得了高产量的原生质体,而有机类(蔗糖、甘露醇、山梨醇)做为稳定剂不甚理想。对120和720菌株的原生质体在高渗再生培养基上进行再生试验,再生率分别为52%和65%。     

褐云玛瑙螺的生态研究

褐云玛瑙螺(Achatina fulica Férussac)在闽粤一些地区俗称花螺、菜螺、东风螺、非洲蜗牛等。原产地为东非大陆,上世纪中期,传入印度,以后逐渐扩及东南亚与南洋群岛,第二次世界大战期间传入美洲。     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

Comparison of in vitro decomposition of bryophytic and tracheophytic plant material

The fossil record of bryophytes is generally poor and infertile plants attributable to liverworts and mosses could also be thalloid vascular plant gametophytes or herbaceous lycophytes respectively. The paucity of the bryophytic record could be the result of relatively rapid degradation of bryophytic material in comparison to that of vascular plants, the absence of lignified cells in bryophytes sustaining this belief. However, certain organs of bryophytes are as robust as those of vascular plants (e.g. spores) and the hydroxybenzofuran polymers produced by some mosses could be of similar preservational resistance to lignins. A simplistic experiment to test the relative resistance to decay of bryophytic material has been undertaken. Its findings suggest that bryophytic plant material has a similar preservational potential to that of a selected vascular plant, particularly in organic rich sediments. This result may be construed to imply that bryophytes were indeed less abundant in the preservational environments of the Coal Measures than might be expected on the basis of current palaeoenvironmental reconstructions.     

Genetic Analysis of an Emerging GII.P2–GII.2 Norovirus Associated with a 2016 Outbreak of Acute Gastroenteritis in China

<正>Dear Editor,Noroviruses are positive-sense, single-stranded RNA viruses belonging to Caliciviridae and account for more than 50%of all acute gastroenteritis (AGE) outbreaks worldwide and cause an estimated 200,000 deaths per year among children\5 years of age, primarily in developing countries (Hall et al. 2012; Glass et al. 2009). The norovirus genome contains three open reading frames (ORFs).     

The structure of Crimean-Congo hemorrhagic fever virus Gc is revealed; many more still need an answer

Highlights
1. The structure of glycoprotein Gc, responsible for mediating membrane fusion between cell and CCHFV, is revealed, but many more mysteries remain.
2. Why do only antibodies against Gc have neutralizing effect, but not the one against Gn?
3. Why can NAbs against Gc only be protective in the animals in preventive settings, but not in the therapeutic administration?     

Development of a biosensor assessing SARS-CoV-2 main protease proteolytic activity in living cells for antiviral drugs screening

Highlights:
The biosensor reported in our study can monitor SARS-CoV-2 M^pro activity in living cells instead of in vitro solutions.
The biosensor reported in our study is sensitive and easy to operate.
It is suitable for high-throughput screening.
It has the potential to be used in small animal models.     

Development of functional antibodies against influenza B virus by activation-induced cytidine deaminase in hybridoma cells

Highlights
1. Class-switch recombination was mimicked in hybridomas through a controllable expression system of activation-induced cytidine deaminase.
2. IgG antibodies were generated through this system in an anti-Flu B IgM hybridoma 7G1.
3. IgG1 and IgG2a subtypes of 7G1 present improved antiviral activity in vitro and in vivo.