Literature on archaeological remains of cultivated plants (1997/1998)

Publications on archaeological remains of cultivated plants have been collected, mainly from 1997, with some earlier and some from 1998. A list is given of the finds according to taxon, country, site, and age.     

Structure et composition chimique élémentaire de quelques coquilles d'œufs de dinosaures du Jurassique et du Crétacé d'Amérique du Nord

Structure and chemical composition of some dinosaur eggshells from Jurassic and Cretaceous of North America. Microstructural analyses of some dinosaur eggshells from Jurassic and Cretaceous sites of North America show a large variability in the state of preservation. Outer and inner surfaces are often hidden by secondary deposits, and the tubercles or ridges and spherolites are not visible. Chemical analyses show that some fragments are strongly enriched in Si. There is a good correlation between the preservation of the structures and the chemical contents. Diagenetic processes are different from those described in the samples from Southern France.     

Influence of olfactory stimulants on resistance/susceptibility of pearl millet, Pennisetum americanum to the rice weevil, Sitophilus oryzae

The orientation responses of the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) as influenced by the olfactory stimulants emanating from either resistant or susceptible pearl millet, Pennisetum americanum, kernels were studied using a Y-tube olfactometer. The rice weevils were more attracted towards odours from millet grains than to blank controls and to susceptible entries more than to resistant entries, in general. However, there were exceptions. Odours from some resistant entries caused statistically the same, or even more positive orientations than those from some susceptible entries, and this suggests that the relative resistance of an entry and its olfactory attractiveness may not be strongly related, or that the resistance to infestation might be influenced by factors other than attractiveness. The partial damage of the millet kernel pericarp by abrasion slightly increased the orientational response of the weevils to odours from some susceptible and some resistant entries alike.     

Literature on archaeological remains of cultivated plants (1998/1999)

Publications on archaeological remains of cultivated plants have been collected, mainly from 1998, with some earlier ones, and some from 1999, A list is given of the finds according to taxon, country, site, and age     

Diversity of isolates of Rhodococcus equi from Australian Thoroughbred horse farms

Pulsed field gel electrophoresis of restriction endonuclease digested genomic DNA from a collection of clinical isolates of Rhodococcus equi was used to compare strain diversity on different Thoroughbred horse farms over time. Restricted diversity was found among the isolates tested, as the same strains were detected on multiple farms and in multiple years. Marked variation occurred in strain prevalence with some strains being represented by single isolates, and the most prevalent by 26 isolates. There were dominant strains on some farms and the prevalence of some strains differed between farms. Infection with multiple strains was noted in some cases where multiple isolates from a single foal were examined.     

侵染细胞质膜附近小泡的来源及其作用

箭舌豌豆根瘤幼龄侵染细胞的壁和质膜比较光滑,成熟侵染细胞与此不同,不仅细胞壁厚薄均,有较多的胞间连丝,而且质膜常常内陷形成各种突起,然后离质膜形成小泡。这些位于质膜附近的小泡体积较小,多呈圆形,既可单独存在,也可多个聚在一起。在向细胞中央移动中,有的小泡靠近细胞质膜,甚至与细菌周期融合,有的小泡不民附近的小液泡融合变为较大液泡,并常用降解程度不同的细菌位于其中,在衰老侵染细胞中,细胞壁附近有小泡,     

Tools and collaborative environments for bioinformatics research

Advanced research requires intensive interaction among a multitude of actors, often possessing different expertise and usually working at a distance from each other. The field of collaborative research aims to establish suitable models and technologies to properly support these interactions. In this article, we first present the reasons for an interest of Bioinformatics in this context by also suggesting some research domains that could benefit from collaborative research. We then review the principles and some of the most relevant applications of social networking, with a special attention to networks supporting scientific collaboration, by also highlighting some critical issues, such as identification of users and standardization of formats. We then introduce some systems for collaborative document creation, including wiki systems and tools for ontology development, and review some of the most interesting biological wikis. We also review the principles of Collaborative Development Environments for software and show some examples in Bioinformatics. Finally, we present the principles and some examples of Learning Management Systems. In conclusion, we try to devise some of the goals to be achieved in the short term for the exploitation of these technologies.     

Nuclear insertion sequences of mitochondrial DNA predominate in hair but not in blood of elephants

Hair has become a widely used source of DNA in population genetics, forensics, and conservation biology. Here we report that PCR primers that amplify a segment of the mitochondrial control region from blood DNA amplify primarily integrated nuclear copies of mitochondrial DNA from hair DNA. Thus, in some species, and under some circumstances, DNA from hair may yield unreliable results.     

Human pluripotent stem cells: a progress report

The derivation of diploid human pluripotent stem cell lines from either human blastocysts or embryonic gonads in 1998 attracted a great deal of interest because of the widespread potential applications of these cells in research and in regenerative medicine. Since the initial reports, there has been some progress in the characterisation of blastocyst-derived stem cells, and some technical advances in their manipulation. Conditions for differentiation in vitro of pluripotent stem cells from either blastocysts or gonads have been defined. In some studies, committed progenitor cell populations have been isolated from mixed cultures of differentiating ES cells.     

Excystation of the Sporozoites of Eimeria tenella in Apparently Unbroken Oocysts in the Chicken

SYNOPSIS. Chickens experimentally fed sporulated oocysts of Eimeria tenella were necropsied 5–300 minutes later to study excystation, especially in apparently unbroken oocysts. In birds killed 75–125 minutes after inoculation, there was evidence of excystation in some oocysts recovered from the small and large intestines. Altho not visibly broken, the shells of about 10% of the ones studied were wrinkled or otherwise deformed; many contained active sporozoites, some inside and some outside the sporocysts. During examinations, numerous sporozoites emerged from the sporocysts. Altho evidence was not obtained that excystation from unbroken oocysts was occurring inside the birds, the fact that it occurred in some oocysts during examinations may indicate that it could be taking place. Evidence of excystation was not seen in oocysts with shells that were not visibly altered.     

新西兰的负鼠——一场尚未完结的与外来入侵有袋类的较量（英）

为发展毛皮工业,新西兰19世纪中叶从澳大利亚引入刷尾负鼠（Trichosurus vulpecula),后成为新西兰一大害兽,刷尾负鼠不仅因破坏当地植被,捕食鸟蛋等而严重影响了新西兰的生物多样性,而且因其传播结核病菌对当地畜牧业造成了很大损失,新西兰每年花费巨额资金来控制这一害兽,虽然刷尾负鼠在一些孤立的岛屿和重复自然保护区已完全被消灭或得到有交和的控制,但在新西兰大部分地区其分布却还在扩展,依然威胁着新西兰的生物多样性和农牧业生产,传统的控制方法包括兽夹捕杀,射杀和药物灭杀,其效果不佳的主要原因是：1）受资金的限制;2）小面积控制后因为种群密度减小,负鼠的生育率,存活率随之增高,加上新个体从周围迁入,种群数量迅速恢复,生物防治特别是免疫绝育法被认为是经济,人道及有效的方法,新的研究结果证明刷尾负鼠具有一雄多雌的繁殖方式,而且在雌兽被绝育后,种群中雄兽与雌兽之比率反而增高,因此雌兽绝育可能不会降低雌雄负鼠之间的接触频率,这些研究结果表明免疫绝育控制刷尾负鼠是很有前景的。     

Effects of venom/calyx fluid from the endoparasitic wasp Cotesia plutellae on the hemocytes of its host Plutella xylostella in vitro

Crude venom and calyx fluid from Cotesia plutellae (Hymenoptera Braconidae) were assayed for biological activity toward hemocytes of Plutella xylostella (Lepidoptera Plutellidae). Venom from C. plutellae displayed high activity toward the spreading of plasmatocytes of P. xylostella early in the incubation period, and the inhibition was more severe as the concentration of venom increased. However, most inhibited hemocytes spread normally after being incubated for 4h. No effects were found toward granular cells from the host. Additionally, the venom from C. plutellae had some lethal effects on hemocytes of P. xylostella at high concentrations. In contrast, when incubated with different concentrations of calyx fluid, the spreading of some hemocytes was inhibited, some began to disintegrate, and some were badly damaged with only the nucleus left. After 4h, the majority of hemocytes died. The same results were observed when hemocytes were incubated in calyx fluid together with venom. These results show that calyx fluid from C. plutellae may play a major role in the suppression of the host immune system, whereas venom from C. plutellae has a limited effect on hemocytes and probably synergizes the effect of calyx fluid or polydnavirus.     

Literature on archaeological remains of cultivated plants (1999/2000)

Publications on archaeological remains of cultivated plants have been collected, mainly from 1999, with some earlier and some from 2000. A list is given of the finds according to taxon, country, site, and age. Received November 22, 2000 / Accepted November 27, 2000     

侧根的发生及其激素调控

本文概述了侧根发生及其植物激素调控的研究进展。侧根的发生起源于特定的中柱 鞘细胞,其发生过程可简单地分为侧根发生的起始、侧根原基的形成、侧根分生组织的形成和活化等几个关键时期。参与侧根发生调控的植物激素主要是生长素,它影响到侧根发生过程的各个时期。茉莉酸对侧根的发生也有一定的调控作用。     

异珊瑚研究的新进展

通过对异珊瑚形态构造特征分析,进一步阐明了隔壁的发生方式、隔壁发育阶段、隔壁生长的变演性、隔壁基端与外壁的关系、隔壁的微细构造及其所含的化学成份,枝体表壁和壁面上的构造物特征,横板的形态及枝体繁殖的方式.通过异珊瑚生长特征的分析,探讨了它们的生活环境.结合地层资料归纳了异珊瑚的时空分布并将异珊瑚重新归纳为6科2亚科16属.     

Illegitimate recombination in Xenopus: characterization of end-joined junctions.

When linear DNAs are injected into Xenopus laevis eggs, they are converted into several different kinds of recombination products. Some molecules undergo homologous recombination by a resection-annealing mechanism; some ends are precisely ligated; and some ends are joined by illegitimate means. The homologous and illegitimate products are also generated in nuclear extracts from stage VI Xenopus oocytes. In order to gain insight into the mechanism(s) of illegitimate end joining, we amplified, cloned and sequenced a number of junctions from eggs and from oocyte extracts. The egg junctions fell into three categories: some with no homology at the join point that may have been produced by blunt-end ligation; some based on small, but significant homologies (5-10 bp); and some with matches of only 1 or 2 nucleotides at the joint. Junctions made in oocyte extracts were largely of the latter type. In the extracts, formation of illegitimate joints required the addition of all four deoxyribonucleoside triphosphates and was inhibited by aphidicolin. This indicates that this process involves DNA synthesis, and mechanisms incorporating this feature are considered. The spectrum of recombination products formed in Xenopus eggs is very reminiscent of those produced from DNA introduced into mammalian cells.     

侧根的发生及其激素调控

本文概述了侧根发生及其植物激素调控的研究进展。侧根的发生起源于特定的中柱鞘细胞,其发生过程可简单地分为侧根发生的起始、侧根原基的形成、侧根分生组织的形成和活化等几个关键时期。参与侧根发生调控的植物激素主要是生长素,它影响到侧根发生过程的各个时期。茉莉酸对侧根的发生也有一定的调控作用。     

A review of theropod dinosaurs from the Late Jurassic to mid-Cretaceous of Southeast Asia

Several non-avian theropod dinosaurs, as well as some Mesozoic birds, have been reported from Southeast Asia. The fossils are dominantly found in northeastern Thailand, however, one bizarre theropod has been described from Laos, one theropod has been reported from Malaysia, and some avian and non-avian theropods have been recently reported from Myanmar. The temporal distribution of Southeast Asian theropods ranges from the Late Jurassic to the mid-Cretaceous. All non-avian theropod faunas from Southeast Asia consist of non-maniraptoran tetanurans. They show similarity to Chinese plus Japanese theropods during the Early Cretaceous in broad systematic terms. During this time, megaraptorans can be found only in Japan, Australia, Brazil, and possibly Thailand, whereas tyrannosauroids can be found in China, Europe, possibly Brazil and Australia. Spinosaurids, carcharodontosaurians, and some coelurosaurs such as ornithomimosaurs were almost cosmopolitan. Metriacanthosaurids, on the other hand, were endemic to Europe and Asia including China and Thailand during the Middle to Late Jurassic.     

桃遗传多样性的RAPD分析

采用RAPD技术,利用200个引物筛选的22个10碱基随机引物对桃182个变种,类型,品种进行DNA扩增。对扩增位点上的带型分析,观察到有的引的在某一位点上明显有带的分离,且S65,S459,S167,S60引物在这一位点可以包含一个类群或几个类群全部的供试品种,变种或类型,但各类群都没有各自独特的特征带。聚类图分析表明,来源无性系的品种遗传一致度最大达0．990;有的品种也表现出较大遗传一致度的为0．985;也有的品种的遗传一致度较低,范围在0．686－0．831之间。对桃的分类,以水蜜桃,寿星桃,垂枝桃作为类群划分较明晰,其它品种的类群划分则较困难,从而也说明了原产中国的桃种质资源的遗传多样性丰富。     

Models for the perception of orientation in random dot patterns

The aim of this paper is to summarize and to compare some known mathematical models of orientation perception in random dot patterns and to propose new solutions of this question. The model adequacy is judged from the previously obtained experimental results. Apart from the models based on some simple function of the coordinates of dots forming a pattern, also models derived from the so-called image function of the pattern are analysed. The latter ones were found more flexible to render the different features of experimentally obtained data, mainly in the case of orientation ambiguity for some special patterns. The stochastic variants of the deterministic models are introduced.