Molecular phylogeny of glacial relict species: a case of freshwater Valvatidae molluscs (Mollusca: Gastropoda) in North and East Asia

The study of glacial relict species has been focused on understanding how the biogeographic patterns of species have developed. A number of studies using phylogenetic and population genetics approaches have been conducted for terrestrial glacial relict species, and the mechanisms of their formation have been elucidated. On the other hand, less focus has been placed on glacial relict species inhabiting freshwater systems. In particular, stable lakes can serve as refugia during a glacial period, but research studies on freshwater relict species inhabiting lakes have not been well conducted. In order to clarify the mechanism of the glacial relict species in freshwater, we conducted a molecular phylogeny analysis, divergence time estimation, and a biogeographic reconstruction on freshwater Valvatidae molluscs, which have been considered as a glacial relict in the Japanese Archipelago. Our study shows that the valvatid fauna in the Japanese Archipelago was produced by multiple dispersal events from the Asian continent and by vicariance events during the period of the Pliocene–Quaternary glaciation. It includes multiple relict species that survived interglacial periods in different lakes. These findings suggest that the lakes can serve as refugia not only during glacial periods, but also during interglacial periods.     

Biosynthesis of phosphoglycerides in skeletal muscle in control rats and in rats deficient in essential fatty acids.

1. The specific radioactivities of individual molecular species of phosphoglycerides in the skeletal muscles of control rats and of rats deficient in essential fatty acids have been determined 3 h after intraperitoneal injection of ortho[32P] phosphate. 2. It has been demonstrated that the high average specific radioactivity of phosphoglycerides in muscles of rats deficient in essential fatty acids is due to both increased amounts and increased turnover of 1-palmitoyl-2-oleoyl phosphatidylcholine and phosphatidylethanolamine. 3. The 1-stearoyl-2-arachidonoyl phosphatidylcholine was found to turn over faster than the 1-palmitoyl-2-arachidonoyl species. In rats deficient in essential fatty acids, the 1-stearoyl-2-(5,6,11-eicosatrienoyl) phosphatidylcholine turned over more rapidly than the 1-palmitoyl-2-(5,8,11-eicosatrienoyl) species. Both findings are in constant with similar findings for liver.     

四川当归属植物资源及其开发利用

对四川当归属植物进行了标本查看和资料整理,调查了四川当归属植物资源。结果表明：四川共有当归属植物19种1变种1变型,资源丰富。开发利用潜力大,并对开发利用提出建议。     

Antarctic marine benthic biodiversity in a world-wide latitudinal context

In the 1950s and 1960s, the first data sets were assembled to examine whether or not there was a latitudinal gradient of species richness in the sea. These data comprised very few species and were from very small areas. However, recent data from large species lists covering broad geographical ranges suggest strongly that there is a gradient of increasing species richness from the Arctic to the tropics. However, the Southern Ocean has high species richness and in the southern hemisphere there is no clear evidence of a cline of increasing richness from pole to tropic. The great richness of the Southern Ocean compared with the Arctic is probably due to its great age, the fact that it covers a much larger area and that it has higher structural heterogeneity formed by living organisms. The importance of area as a determinant of species richness needs to be studied in more detail since most studies have been confined to small areas. A number of hypotheses have been proposed to explain the species:area relationship and these are discussed. An alternative explanation for the latitudinal cline in the northern hemisphere is the energy-input hypothesis, but again this has not been adequately tested. Two studies on the relationship between local and regional species richness show a significant positive correlation. These findings suggest that local assemblages are not tightly organised and saturated with species but are open to recruitment from the regional species pool. Whether or not such a relationship holds in Antarctica is unknown. It is concluded that further studies of the Southern Ocean are likely to provide new findings fundamental to the "new" discipline of macroecology, which examines patterns and processes at the geographic scale.     

Arabidopsis ovule development and its evolutionary conservation

Ovules have an important role during the life cycle of the plant, and they provide an excellent model for studying organogenesis in plants. As such, the molecular control of ovule development has been studied for many years. Recent studies in Arabidopsis have revealed important new data concerning ovule primordia formation, ovule identity determination, and patterning. Furthermore, interesting results about ovule development in other species, such as Petunia and rice, have been published recently. In this review, we discuss these recent findings in reference to ovule development in Arabidopsis. We compare available data with those of other species to investigate the evolutionary conservation of the regulatory pathways.     

鸟类利用地磁场定向的机制

地磁场和生物体问的相互作用关系是一个很有趣的未解之迷.虽然对地磁场的生物学作用至今还知之不多,为过近来有关鸟类利用地磁场信息定向的研究取得了较大的进展.很多鸟类能够对地磁场和外加磁场信息做出反应,这些反应可能通过磁场一生物化学过程介导.对此,目前有两种被广为接受的解释,一种认为在鸟喙上方存在一个磁场信息感受器,另一种认为通过视觉成像系统感受磁场信息.另外,最近研究发现磁场信息的感知分析功能有明显的单侧优势特征.虽然目前有关鸟类利用磁场信息定向的研究取得了很多进展,但是要想解释并利用鸟类的磁场定向功能还有很多工作要做.本文结合最近的研究发现对这一有趣的问题进行了综述.     

Plant genome archaeology: evidence for conserved ancestral chromosome segments in dicotyledonous plant species

We have developed genetic maps, based on expressed sequence tags (ESTs) that are homologous to Arabidopsis genes, in four dicotyledonous crop plant species from different families. A comparison of these maps with the physical map of Arabidopsis reveals common genome segments that appear to have been conserved throughout the evolution of the dicots. In the four crop species analysed these segments comprise between 16 and 33% of the Arabidopsis genome. Our findings extend the synteny patterns previously observed only within plant families, and indicate that structural and functional information from the model species will be, at least in part, applicable in crop plants with large genomes.     

Phylogenetic relationships of Carpha and its relatives (Schoeneae, Cyperaceae) inferred from chloroplast trnL intron and trnL-trnF intergenic spacer sequences

Within the tribe Schoeneae (Cyperaceae), the relationships between Carpha and its relatives have not been certain, and the limits and definition of Carpha have been controversial. Further, the relationships of species within Carpha have been unclear. In this study, cladistic analyses based on chloroplast trnL intron and trnL-trnF intergenic spacer sequence data were undertaken to estimate phylogenetic relationships in and around Carpha. This study found that Trianoptiles is sister to Carpha; Ptilothrix is sister to Cyathochaeta rather than to Carpha as suggested by some former authors; and Gymnoschoenus is distant from Carpha and its close relatives. The merging of Schoenoides back into Oreobolus is supported. The findings also revealed the non-monophyletic status of Costularia and of Schoenus, and indicated the phylogenetic relationships of species within Carpha.     

Food, pharmaceutical and industrial potential of Carissa genus: an overview

Shrubs belonging to Carissa genus (Apocyanaceae family) are potential sources of food, medicine and fuel, yet they are wallowing under obscurity and rarely been exploited. Edibility of the pulpy Carissa fruits is known to only a meagre few. Since antiquity, the stem, root bark, leaves, fruit and seed extracts have been used in folklore medication. Now, the emerging scientific investigations are validating the ethno-medicinal uses of these species. Bioactive compounds which include viz. polyphenolics, flavonoids, flavanones, lignans and sesquiterpenes imparting therapeutic potential to these species have been isolated. In vitro and in vivo studies have shown these species to have antioxidant, analgesic, anti-inflammatory, hypolipidemic, wound healing, antimicroabial, antidiabetic, antiepileptic, anticancer, diuretic, nephrotoxicity amelioration and hepatoprotective activity. This miraculous plant extract has also been effective in the management of veterinary ailments. Apart from the medicinal attributes, this genus also holds promise as a suitable alternative crop for harvesting renewable energy. Micropropagtion is being tried for rapid multiplication of the valuable species. This review summarizes the recent findings for promoting the versatility of this genus.     

Microorganisms surviving for 5300 years

Abstract Recently, the well-preserved corpse of a prehistoric man with an age of approximately 5300 years bp was discovered in the Central European Alps. Analysis of materials associated with the individual has revealed the presence of microorganisms which are believed to have survived since the time of death. So far, two fungi have been isolated and identified as species of the genera Chaetomium and Absidia , respectively. In addition, we have obtained one bacterial isolate which we have identified as a Streptomyces species. Our findings demonstrate that microorganisms can remain viable under appropriate circumstances for thousands of years. The isolates may enable us to study evolutionary trends within microorganisms.     

Trichosporon species isolated from guano samples obtained from bat-inhabited caves in Japan

Yeasts from caves have rarely been examined. We examined yeasts collected from bat guano samples from 20 bat-inhabited limestone and volcanic caves located in 11 prefectures in Japan. Of approximately 700 yeast-like colonies, nine Trichosporon species were recovered from 15 caves. Two of these were known species, and the remaining seven are potentially novel species, based on molecular phylogenetic analyses. In addition to Trichosporon species, identifiable strains of eight ascomycetous yeasts and one basidiomycetous yeast were recovered at frequencies of 5 to 35%. Our findings suggest that Trichosporon spp. are the major yeast species in bat guano in Japan and that bat guano is a potentially rich source of previously undescribed yeast species.     

Comparative IR study of solid hydrate decavanadates and polyvanadates in acidic aqueous solution

An attempt has been made to compare i.r. spectra of polyvanadate solutions with those of solid polyvanadates, in order to solve the problem if aqueous solution decavanadate species have the same structure as reported in solid hydrate decavanadates, and if hexavanadate species are coexisting with them.The i.r. spectra directly obtained from water solutions were unreliable; so, solution species have been extracted into a low absorbing organic phase. A previous control showed that no modifications of existing species were occurring for the phase transfer. In this way, evidence resulted for a complete identity between aqueous solution and solid decavanadate structure, and for a lack of hexavanadate species, at least within the sensitivity limits of the i.r. technique.These findings are in agreement with a recent Raman investigation, but appear in contrast with NMR and complexation data. A new interpretation of NMR data is suggested, leading to the removal of disagreement.     

Interspecific hybridization, a matter of pioneering? Insights from Atlantic salmon and brown trout

Interspecific hybridization may occur in situations of recent contact between a colonizer and a resident species, being more intense in the colonization front. Atlantic salmon Salmo salar and brown trout S. trutta have been sympatric species since their origin and they share spatial and temporal spawning niches, exhibiting low levels of bidirectional interspecific hybridization and introgression throughout their distribution range. Different causes have been identified for increased hybridization, from escapes or deliberate releases of domesticated fish to sneaking male behavior. We have examined hybridization rates and direction in different situations of advance of one of these species into a territory formerly inhabited by the other (247 samples were analyzed in northern Spain and 487 in Kerguelen Islands). In all cases, hybrids found in the colonization front were offspring of colonizer females and resident males. We hypothesize that these findings are the result of adaptive relaxed mate choice of colonizing females, regardless of the relative abundance of each species.     

Ant community structure during forest succession in a subtropical forest in South-East China

Understanding how communities respond to environmental gradients is critical to predict responses of species to changing habitat conditions such as in regenerating secondary habitats after human land use. In this study, ground-living ants were sampled with pitfall traps in 27 plots in a heterogeneous and diverse subtropical forest to test if and how a broad set of environmental variables including elevation, successional age, and tree species richness influence ant diversity and community composition. In total, 13,441 ant individuals belonging to 71 species were found. Ant abundance was unrelated to all environmental variables. Rarefied ant species richness was negatively related to elevation, and Shannon diversity decreased with shrub cover. There was considerable variation in ant species amongst plots, associated with elevation, successional age, and variables related to succession such as shrub cover. It is shown that younger secondary forests may support a species-rich and diverse community of ants in subtropical forests even though the species composition between younger and older forests is markedly different. These findings confirm the conservation value of secondary subtropical forests, which is critical because subtropical forests have been heavily exploited by human activities globally. However, the findings also confirm that old-growth forest should have priority in conservation as it supports a distinct ant community. Our study identifies a set of ant species which are associated with successional age and may thus potentially assist local conservation planning.     

Hemoglobins from bats (Myotis myotis and Rousettus aegyptiacus): a possible example of molecular adaptation to different physiological requirements

The functional properties of the hemoglobin systems from two different species of bat i.e. Rousettus aegyptiacus and Myotis myotis have been studied as a function of chloride, polyphosphates, pH and temperature. Apart from overall similarities shared with most mammalian hemoglobins, the two systems show significant differences with respect to the effect of chloride and temperature sensitivity. These findings have been related to the different physiological needs of the two species.     

Genetic control of multiple births in low ovulating mammalian species

In mammals, litter size is a highly variable trait. Some species such as humans or cattle are monotocous, with one or sometimes two newborns per birth, whereas others, the polytocous species such as mice or pigs, are highly prolific and often produce a dozen newborns at each farrowing. In monotocous species, however, two or three newborns per birth may sometime be unwanted. In more polytocous species such as sheep or pigs, litter size is studied in order to increase livestock prolificacy. By contrast, twinning rates in humans or cattle may increase birth difficulties and health problems in the newborns. In this context, the aim of our review was to provide a clearer understanding of the genetic and physiological factors that control multiple births in low-ovulating mammalian species, with particular focus on three species: sheep, cattle, and humans, where knowledge of the ovulation rate in one may enlighten findings in the others. This article therefore reviews the phenotypic and genetic variability observed with respect to ovulation and twinning rates. It then presents the QTL and major genes that have been identified in each species. Finally, we draw a picture of the diversity of the physiological mechanisms underlying multiple ovulation. Although several major genes have been discovered in sheep, QTL detection methods in humans or cattle have suggested that the determinism of litter size is complex and probably involves several genes in order to explain variations in the number of ovulations.     

Genetic control of multiple births in low ovulating mammalian species

In mammals, litter size is a highly variable trait. Some species such as humans or cattle are monotocous, with one or sometimes two newborns per birth, whereas others, the polytocous species such as mice or pigs, are highly prolific and often produce a dozen newborns at each farrowing. In monotocous species, however, two or three newborns per birth may sometime be unwanted. In more polytocous species such as sheep or pigs, litter size is studied in order to increase livestock prolificacy. By contrast, twinning rates in humans or cattle may increase birth difficulties and health problems in the newborns. In this context, the aim of our review was to provide a clearer understanding of the genetic and physiological factors that control multiple births in low-ovulating mammalian species, with particular focus on three species: sheep, cattle, and humans, where knowledge of the ovulation rate in one may enlighten findings in the others. This article therefore reviews the phenotypic and genetic variability observed with respect to ovulation and twinning rates. It then presents the QTL and major genes that have been identified in each species. Finally, we draw a picture of the diversity of the physiological mechanisms underlying multiple ovulation. Although several major genes have been discovered in sheep, QTL detection methods in humans or cattle have suggested that the determinism of litter size is complex and probably involves several genes in order to explain variations in the number of ovulations.

     

Can plant biochemistry contribute to understanding of invasion ecology?

Ecologists have long searched for an explanation as to why some plant invaders become much more dominant in their naturalized range than in their native range, and, accordingly, several non-exclusive ecological hypotheses have been proposed. Recently, a biochemical explanation was proposed--the "novel weapons hypothesis"--based on findings that Centaurea diffusa and Centaurea maculosa produce bioactive compounds (weapons) that are more active against na?ve plant species in the introduced range than against co-evolved species in the native range. In this Opinion article, we revise and expand this biochemical hypothesis and discuss experimental and conceptual advances and limitations.     

Molecular cloning and sequencing of metallothionein in squamates: New insights into the evolution of the metallothionein genes in vertebrates

Metallothioneins are cysteine-rich, metal-binding proteins ubiquitously expressed in living organisms. In the last past years, a plethora of vertebrate metallothionein sequences have become available, but so far there has been an almost absolute lack of data about sequences of metallothionein of non-avian diapsida. In the framework of the investigations on structural and functional properties of non-mammalian metallothioneins, we have cloned and sequenced the cDNAs encoding for metallothioneins of 10 squamate reptiles, belonging to 5 different infraorders. These sequences have been used to gain insight into the evolutionary history of metallothioneins in reptiles. Phylogenetic analysis shows that reptilian metallothionein phylogeny is inconsistent with the species phylogeny. Such findings allow us to hypothesize that the identified metallothionein in each squamate species used for this study might be considered a paralogous gene derived from more events of gene duplication and losses occurred during the diversification of the squamate species. Finally, through vertebrate metallothionein comparisons and phylogenetic analysis, we also add a novel contribution to the understanding of the evolution of metallothionein genes along the major vertebrate lineages.     

Paedomorphosis as an Evolutionary Driving Force: Insights from Deep-Sea Brittle Stars

Heterochronic development has been proposed to have played an important role in the evolution of echinoderms. In the class Ophiuroidea, paedomorphosis (retention of juvenile characters into adulthood) has been documented in the families Ophiuridae and Ophiolepididae but not been investigated on a broader taxonomic scale. Historical errors, confusing juvenile stages with paedomorphic species, show the difficulties in correctly identifying the effects of heterochrony on development and evolution. This study presents a detailed analysis of 40 species with morphologies showing various degrees of juvenile appearance in late ontogeny. They are compared to a range of early ontogenetic stages from paedomorphic and non-paedomorphic species. Both quantitative and qualitative measurements are taken and analysed. The results suggest that strongly paedomorphic species are usually larger than other species at comparable developmental stage. The findings support recent notions of polyphyletic origin of the families Ophiuridae and Ophiolepididae. The importance of paedomorphosis and its correct recognition for the practice of taxonomy and phylogeny are emphasized.