The distribution of calanoid copepods in the plankton of Wisconsin Lakes

Zooplankton communities from 499 lakes were examined for calanoid copepod species. Limnocalanus macrurus and Senecella calaloides are confined to Lakes Michigan, Superior and one inland lake each. Eurytemora affinis has recently become established in the coastal waters of Lakes Michigan and Superior. Epischura lacustris is present in the summer plankton of a wide variety of lake types. Aglaodiaptomus leptopus is sensitive to fish predation and confined to small lakes without fish. Leptodiaptomus ashlandi is restricted to Lakes Michigan and Superior, but L. sicilis is also found in some inland lakes. Leptodiaptomus minutus is a boreal species found mostly in lakes of the far north. Skistodiaptomus oregonensis is the most commonly occurring calanoid and seems well adapted to lakes of the meso-to low eutrophic types. Skistodiaptomus pallidus is also generally distributed throughout the state, but less common than oregonensis and adapted to more eutrophic lakes. Leptodiaptomus siciloides and A. clavipes are western species, adapted to eutrophic lakes, which are expanding their ranges eastward, aided by cultural eutrophication.     

Organization of the origins of replication of the chromosomes of Mycobacterium smegmatis, Mycobacterium leprae and Mycobacterium tuberculosis and isolation of a functional origin from M. smegmatis

The genus Mycobacterium is composed of species with widely differing growth rates ranging from approximately three hours in Mycobacterium smegmatis to two weeks in Mycobacterium leprae. As DNA replication is coupled to cell duplication, it may be regulated by common mechanisms. The chromosomal regions surrounding the origins of DNA replication from M. smegmatis, M. tuberculosis, and M. leprae have been sequenced, and show very few differences. The gene order, rnpA-rpmH-dnaA-dnaN-recF-orf-gyrB-gyrA, is the same as in other Gram-positive organisms. Although the general organization in M. smegmatis is very similar to that of Streptomyces spp., a closely related genus, M. tuberculosis and M. leprae differ as they lack an open reading frame, between dnaN and recF, which is similar to the gnd gene of Escherichia coli. Within the three mycobacterial species, there is extensive sequence conservation in the intergenic regions flanking dnaA, but more variation from the consensus DnaA box sequence was seen than in other bacteria. By means of subcloning experiments, the putative chromosomal origin of replication of M. smegmatis, containing the dnaA-dnaN region, was shown to promote autonomous replication in M. smegmatis, unlike the corresponding regions from M. tuberculosis or M. leprae.     

Succession in zooplankton and hydrophytes of a seasonal water on the west coast of South Africa

Paramesochra mielkei sp.n. is described and figured from the interstices of subtidal sandy sediments off the SW Dutch coast. Kunz' (1981) phylogenetic scheme of the Paramesochridae Lang, 1948 is re-examined and it is suggested that the family comprises two phyletic lines which originated early in paramesochrid evolution. Translation into Linnean hierarchies implies the establishment of two new sub-families. Within the primitive Diarthrodellinae subfam. n., Tisbisoma Bozic, 1964 is ancestral to Diarthrodella Klie, 1949 s.l. and Rossopsyllus Soyer, 1975. Remanea Klie, 1929 is transferred to the Paramesochrinae subfam. n. which comprises the genera of both the Scottopsyllus- and the Paramesochra-group. The aberrant genus Caligopsyllus Kunz, 1975, standing close to Apodopsyllus, is removed from the Paramesochra-group. P. brevifurca Galhano, 1970 is splitted into two subspecies and replaced in the genus Paramesochra. An attempt is made to assess the phyletic interrelationships of the Paramesochra-species and the resulting cladogram splits the genus into four species-groups. P. mielkei sp.n. is referred to the dubia-group and seems to be closely related to P. borealis Geddes, 1981. Finally, an amended diagnosis and a revised key to the species of the genus Paramesochra are presented.     

Approximate matching of regular expressions

Given a sequenceA and regular expressionR, theapproximate regular expression matching problem is to find a sequence matchingR whose optimal alignment withA is the highest scoring of all such sequences. This paper develops an algorithm to solve the problem in timeO(MN), whereM andN are the lengths ofA andR. Thus, the time requirement is asymptotically no worse than for the simpler problem of aligning two fixed sequences. Our method is superior to an earlier algorithm by Wagner and Seiferas in several ways. First, it treats real-valued costs, in addition to integer costs, with no loss of asymptotic efficiency. Second, it requires onlyO(N) space to deliver just the score of the best alignment. Finally, its structure permits implementation techniques that make it extremely fast in practice. We extend the method to accommodate gap penalties, as required for typical applications in molecular biology, and further refine it to search for substrings ofA that strongly align with a sequence inR, as required for typical data base searches. We also show how to deliver an optimal alignment betweenA andR in onlyO(N+logM) space usingO(MN logM) time. Finally, anO(MN(M+N)+N ²logN) time algorithm is presented for alignment scoring schemes where the cost of a gap is an arbitrary increasing function of its length.     

Systematic revision of the catfish genusSilurus,with description of a new species from Thailand and Burma

On the basis of external morphology and anatomy, 17 scpeies of the genusSilurus Linnaeus including a new species,S. torrentis from Thailand and Burma, are recognized as valid.S. bedfordi Regan is synonymized withS. asotus, andS. goae Haig is transferred to the genusOmpok. From an anatomical study of 12 species, the diagnostic feature of the genusParasilurus Bleeker is revealed to be invalid, and the genus is synonymized withSilurus. From the phylogenetic analysis, the genusSilurus is divided into two major species groups, thecochinchinensis group which is disributed mainly in Southeast Asia, and theglanis group which is further separated into three subgroups occurring separately in East Asia and Europe. The pattern of distribution and relationships between ontogeny and phytogeny in the genusSilurus are briefly discussed.     

A new tribe, Epistomentini, of Buprestidae (Coleoptera) with a redefinition of the tribe Chrysochroini

A new tribe Epistomentini is designated to include Epistomentis Solier, Cyria Solier (with which Cyrioides Carter and Xenocyria Obenberger are synonymized), Diadoxus Thomson, Cyrioxus Hoschek, and a new genus and species Araucariana queenslandica, which is described. The tribe Chrysochroini is redefined, and Epidelus Deyrolle, Cyalithus Thomson, Cyalithoides Fisher and Chrysopistus Thery are transferred to it from the Chalcophorini. Chalcophoropsis Thomson is transferred from the Chrysochroini to the Chalcophorini. A reassessment of the value of some characters used in the higher classification of the Buprestidae is given.     

A Molecular Phylogeny of Lilium in the Internal Transcribed Spacer Region of Nuclear Ribosomal DNA

Phylogenetic relationships among 55 species of Lilium, Cardiocrinum giganteum, and Nomocharis saluenensis were inferred from nucleotide sequence variations in the internal transcribed spacer (ITS) regions of 18S–25S nuclear ribosomal DNA. The phylogeny derived from ITS sequences estimated using maximum-likelihood methods indicated that (1) most of the species construct their own clade according to the classification based on morphological features at the section level; (2) section Daurolirion is not independent of Sinomartagon, and it is appropriate to integrate two sections as Sinomartagon; (3) it is appropriate that L. henryi and L. bulbiferum are classified into subsection 6a and Sinomartagon–Daurolirion, respectively; (4) subsection 6b is much closer to Sinomartagon than subsection 6a and Archelirion, and it arose directly from Sinomartagon; and (5) Lilium is much closer to Nomocharis than Cardiocrinum. Phylogenetic estimation using sequences of the ITS region is suitable at the levels of genus, section, and most of subsection. Received: 18 December 1998 / Accepted: 14 March 1999     

Echidnopsis thulinii sp. nov. (Apocynaceae–Asclepiadoideae) with a review of the infrageneric classification of the genus

Echidnopsis thulinii M. G. Gilbert is described from northern Somalia. The infrageneric classification of Echidnopsis Hook. f. is reviewed in the light of recently published molecular phylogenies. The new species belongs to E. sect. Echidnopsis and a key to the species of this section is provided. A lectotype, supported by an epitype, is designated for E. virchowii K. Schum. Echidnopsis sect. Profundicoronata Bruyns is included within sect. Vadosicoronata Bruyns and two new sections recognised: E. sect. Pseudopectinaria (Lavranos) M. G. Gilbert, based on the genus Pseudopectinaria Lavranos, and E. sect. Sobolifera M. G. Gilbert. A key is given to the sections of Echidnopsis.     

Characterization of mariner transposon from the genome of Himasthla elongata fluke

A novel DNA-transposon Hemar1 has been identified and characterized in the genome of the flatworm Himasthla elongata. This transposon is a representative of the mariner family, which is widely spread in eukaryotes; it belongs to the capitata subfamily and is highly homologous to the mariner element of the freshwater turbellarian worm Dugesia tigrina. The Hemar1 transposon has been established as a dispersed repeat and accounts for about 0.01% of the H. elongata genome. The identified Hemar1 element is a convenient tool for the further study of the functioning of mobile elements in the H. elongata genome.     

Temperature regulation of membrane composition in the Firmicute,Enterococcus faecalis,parallels that of Escherichia coli

Both Enterococcus faecalis and Escherichia coli can undergo abrupt temperature transitions in nature. E. coli changes the composition of its phospholipid acyl chains in response to shifts growth temperature. This is mediated by a naturally temperature sensitive enzyme, FabF (3-ketoacyl-acyl carrier protein synthase II), that elongates the 16 carbon unsaturated acyl chain palmitoleate to the 18 carbon unsaturated acyl chain, cis-vaccenate. FabF is more active at low temperatures resulting in increased incorporation of cis-vaccenoyl acyl chains into the membrane phospholipids. This response to temperature is an intrinsic property of FabF and does not require increased synthesis of the enzyme. We report that the FabF of the very divergent bacterium, E. faecalis, has properties very similar to E. coli FabF and is responsible for changing E. faecalis membrane phospholipid acyl chain composition in response to temperature. Moreover, expression E. faecalis FabF in an E. coli ∆fabF strain restores temperature regulation to the E. coli strain.     

A Microenvironment Based Model of Antimitotic Therapy of Gompertzian Tumor Growth

A model of tumor growth, based on two-compartment cell population dynamics, and an overall Gompertzian growth has been previously developed. The main feature of the model is an inter-compartmental transfer function that describes the net exchange between proliferating (P) and quiescent (Q) cells and yields Gompertzian growth for tumor cell population N = P + Q. Model parameters provide for cell reproduction and cell death. This model is further developed here and modified to simulate antimitotic therapy. Therapy decreases the reproduction-rate constant and increases the death-rate constant of proliferating cells with no direct effect on quiescent cells. The model results in a system of two ODE equations (in N and P/N) that has an analytical solution. Net tumor growth depends on support from the microenvironment. Indirectly, this is manifested in the transfer function, which depends on the proliferation ratio, P/N. Antimitotic therapy will change P/N, and the tumor responds by slowing the transfer rate from P to Q. While the cellular effects of therapy are modeled as dependent only on antimitotic activity of the drug, the tumor response also depends on the tumor age and any previous therapies—after therapy, it is not the same tumor. The strength of therapy is simulated by the parameter λ, which is the ratio of therapy induced net proliferation rate constant versus the original. A pharmacodynamic factor inversely proportional to tumor size is implemented. Various chemotherapy regimens are simulated and the outcomes of therapy administered at different time points in the life history of the tumor are explored. Our analysis shows: (1) for a constant total dose administered, a decreasing dose schedule is marginally superior to an increasing or constant scheme, with more pronounced benefit for faster growing tumors, (2) the minimum dose to stop tumor growth is age dependent, and (3) a dose-dense schedule is favored. Faster growing tumors respond better to dose density.     

Thermal inactivation of maltase and its application to temperature-sensitive mutants of yeast

Summary Phage P22 mutationc27 defines a site required for establishment, but not maintenance of repressor synthesis. This study confirms that P22c27 is able to synthesize repressor if active repressor is present. An interaction involving gene products ofc1 andc3 and the sitec27 retards expression of the lytic genes of P22. Mutations in genec1 eliminate the retardation of lytic gene expression, butc27 does not alleviate the retardation. These results are used to construct a model that postulates that binding ofc1 andc3 products to DNA at or nearc27 is sufficient to cause retardation of lytic gene expression. The functioning ofc27 is contrasted to that of the analogouscy mutants of λ. The effect of thec27 mutation upon alleviation of “c1 repression” was studied in a partial revertant ofSalmonella typhimurium Pox-1 in whichc1 repression is exaggerated. The higher frequency of lysogenization seen in the mutant host is related to enhancedc1 repression.     

Larvae of Ceratocanthidae and Hybosoridae (Coleoptera: Scarabaeoidea): study of morphology, phylogenetic analysis and evidence of paraphyly of Hybosoridae

Abstract. Larvae of the scarabaeoid genera Germarostes Paulian, Cyphopisthes Gestro, Paulianostes Ballerio, Ceratocanthus White, Pterorthochaetes Gestro, Madrasostes Paulian, Astaenomoechus Martínez & Pereira (Ceratocanthidae) and Hybosorus Macleay, Phaeochrous Castelnau, and Anaides Westwood (Hybosoridae) are described, keyed and illustrated with fifty‐seven drawings. A phylogenetic analysis of these two families based on larval morphology is presented. Fifty‐four larval morphological and three biological characters from twenty‐seven taxa revealed nineteen equally parsimonious cladograms. The monophyly of (Ceratocanthidae + Hybosoridae) is supported by four unambiguous unique synapomorphies: dorsal medial endocarina on cranium extended anteriorly into frontal sclerite; presence of large membranous spot on apical antennomere; labium dorsally with four pores in centre (secondarily reduced to two pores in some groups); and presence of stridulatory organ on fore‐ and middle legs (secondarily reduced in some groups). Our analysis suggests that the family Hybosoridae is paraphyletic with respect to Ceratocanthidae. The clade comprising the hybosorid genera Hybosorus and Phaeochrous is the sister group of the remaining Hybosoridae plus Ceratocanthidae. It is supported by two unambiguous synapomorphies: two apical antennomeres completely joined and the stridulatory organ represented by seven to nine large teeth anteriorly on the middle leg. The hybosorid genus Anaides is a sister group to the remaining Hybosoridae plus Ceratocanthidae (without Hybosorus and Phaeochrous) and the ceratocanthid genus Germarostes is a sister group to the remaining Hybosoridae plus Ceratocanthidae (without Hybosorus, Phaeochrous and Anaides). The ceratocanthid genera Cyphopisthes, Astaenomoechus, Paulianostes, Pterorthochaetes, and Madrasostes constitute a sister group to the hybosorid genus Cryptogenius and are supported by the presence of two reversions: two dorsal pores on labium and completely reduced stridulatory organs on fore‐ and middle legs.     

中国桑科植物属的空间分布及多样性

该研究以FRPS《中国植物志》全文电子版网站、中国在线植物志(eFlora)网站和国家标本资源共享平台(NSII)网站收录的全部中国桑科植物数据为基础,以部分省的植物志以及正式发表的论文为补充,查找每一个桑科植物的具体分布地点(精确到县一级),并采用地理信息系统技术,以县为空间数据的基本单元,以桑科12属的植物为研究对象,制作属的空间分布图,计算空间相似性系数,分析桑科植物各属的空间多样性及其差异。结果表明:(1)中国桑科植物中桑属的分布最广,橙桑属的分布最狭窄。(2)橙桑属与其他属的空间分布相似性系数均较低(0~0.0444),其中橙桑属与见血封喉属和牛筋藤属的相似性系数均为0,表明橙桑属与其他属的分布几乎没有重叠区;榕属与构属和柘属的空间分布相似性系数分别为0.7394和0.6795,表明这3属的空间分布有较多的重叠区;见血封喉属的分布范围较广,从热带到亚热带地区均有。(3)中国桑科植物属的多样化中心(保护区域)集中在热带和亚热带地区,其中波罗蜜属和葎草属的多样化中心均在云南,鹊肾树属的多样化中心在海南,柘属的多样化中心从热带、南亚热带扩大至中亚热带地区;榕属在中国有98个种,多样化中心分布在甘肃东南部、贵州东北部、云南南部、广西西南部、台湾南部和海南西部;桑属(11个种)的多样化中心分布在重庆南部、湖北南部、湖南西北部、贵州中南部、云南东部和广西西部。研究认为,中国桑科植物属的多样化中心各有特点,基于县的空间分布及多样性研究结果能够具体确定中国桑科植物属的最小保护区域;且该研究结果支持贵州地区是桑属植物的分化中心和过渡中心。     

The genetic control of isovitexin-glycosylation in the petals of Melandrium album

Summary The glycosylation of flavones in the petals of Melandrium album is shown to be controlled by the genes G, X and A. In the presence of the recessive alleles of these genes, only the aglycone isovitexin (6-C-glucosylapigenin) is found in the petals. The gene G controls the transfer of glucose, the gene X the transfer of xylose to the 7-hydroxyl group of isovitexin. The gene G is epistatic over X. In the presence of the gene A arabinose is coupled to the carbon-carbon bound glucose of isovitexin. In the presence of both G and A, or both X and A the corresponding di-glycosides are formed.The petals of the plants in which all genes for the flavone glycosylation are present in the homozygous recessive form are of a particular phenotype.