Indo-West Pacific patterns of genetic differentiation in the high-dispersal starfish Linckia laevigata

Genetic variation in four natural populations of the starfish Linckia laevigata from the Indo-West Pacific was examined using restriction fragment analysis of a portion of the mtDNA including the control region. Digestion with seven restriction enzymes identified 47 haplotypes in a sample of 326 individuals. Samples collected from reef sites within each location were not significantly differentiated based on Φ_ST or spatial distribution of haplotypes, indicating that dispersal is high over short to moderate distances. Evidence of gene flow is further supported by the low divergence among haplotypes and the lack of any clear geographical structuring among different haplotypes in the gene phylogeny. However, analysis of molecular variance ( AMOVA ), Φ_ST and contingency χ² analyses of the spatial distribution of haplotypes demonstrate the presence of significant broad scale population genetic structure among the four widespread locations examined. RFLP data are consistent with high gene flow between the Philippines and Western Australia and moderate gene flow between the Great Barrier Reef (GBR) and Fiji, but only limited gene flow between either the Philippines or Western Australia and either the GBR or Fiji. The presence of mtDNA structure contrasts with previous allozyme data which suggest that dispersal among widely separated locations is equivalent to dispersal among populations within the highly connected GBR studies. This discordance between patterns of gene flow inferred from these two markers cannot be fully accounted for by differences in effective population size for mtDNA. This might suggest that while mtDNA variation may represent contemporary patterns of gene flow, allozyme variation among populations is yet to reach equilibrium between drift and migration over the range surveyed.     

An effective method for isolating DNA from historical specimens of baleen

DNA was isolated from an early twentieth century museum specimen of northern right whale baleen. A system of stringent controls and a novel set of cetacean specific primers eliminated contamination from external sources and ensured the authenticity of the results. Sequence analysis revealed that there were informative nucleotide positions between the museum specimen and extant members of the population and closely related species. The results indicate that museum specimens of baleen can be used to assess historical genetic population structure of the great whales.     

Intrachain disulfide bond in the core hinge region of human IgG4.

IgG is a tetrameric protein composed of two copies each of the light and heavy chains. The four-chain structure is maintained by strong noncovalent interactions between the amino-terminal half of pairs of heavy-light chains and between the carboxyl-terminal regions of the two heavy chains. In addition, interchain disulfide bonds link each heavy-light chain and also link the paired heavy chains. An engineered human IgG4 specific for human tumor necrosis factor-alpha (CDP571) is similar to human myeloma IgG4 in that it is secreted as both disulfide bonded tetramers (approximately 75% of the total amount of IgG) and as tetramers composed of nondisulfide bonded half-IgG4 (heavy chain disulfide bonded to light chain) molecules. However, when CDP571 was genetically engineered with a proline at residue 229 of the core hinge region rather than serine, CDP571 (S229P), or with an IgG1 rather than IgG4 hinge region, CDP571(gamma 1), only trace amounts of nondisulfide bonded half-IgG tetramers were observed. Trypsin digest reversephase HPLC peptide mapping studies of CDP571 and CDP571(gamma 1) with on-line electrospray ionization mass spectroscopy supplemented with Edman sequencing identified the chemical factor preventing inter-heavy chain disulfide bond formation between half-IgG molecules: the two cysteines in the IgG4 and IgG1 core hinge region (CPSCP and CPPCP, respectively) are capable of forming an intrachain disulfide bond. Conformational modeling studies on cyclic disulfide bonded CPSCP and CPPCP peptides yielded energy ranges for the low-energy conformations of 31-33 kcal/mol and 40-42 kcal/mol, respectively. In addition, higher torsion and angle bending energies were observed for the CPPCP peptide due to backbone constraints caused by the extra proline. These modeling results suggest a reason why a larger fraction of intrachain bonds are observed in IgG4 rather than IgG1 molecules: the serine in the core hinge region of IgG4 allows more hinge region flexibility than the proline of IgG1 and thus may permit formation of a stable intrachain disulfide bond more readily.     

Design, synthesis, expression, and characterization of the genes for mouse Fc gamma RIIb1 and Fc gamma RIIb2 cytoplasmic regions.

The cytoplasmic regions of the mouse low-affinity Fc gamma RII isoforms, mFc gamma RIIb1, and mFc gamma RIIb2, play a key role in signal transduction by mediating different cellular functions. mFc gamma RIIb1 has a 94-residue cytoplasmic region, whereas mFc gamma RIIb2 has a 47-residue cytoplasmic region. Genes encoding the cytoplasmic regions of mFc gamma RIIb1 (b1-94) and mFc gamma RIIb2 (b2-47) were designed, synthesized, and expressed as fusion proteins in Escherichia coli. A sequence-specific protease, thrombin, was used to release the b1-94 peptide, which was purified by using HPLC. The b2-47 peptide was synthesized chemically. CD spectropolarimetry was employed to examine the secondary structures of b1-94 and b2-47. These studies were conducted in aqueous solution, in mixtures of water and trifluoroethanol or methanol, and as a function of temperature. The results indicate that the b1-94 and b2-47 structures are sensitive functions of the solvent environment, and that nonaqueous solvents induce significant alpha-helical structure.     

Conservation and management issues of Prespa National Park

The present article describes the human activities inthe area and their changes and trends, given that thecontemporary nature conservation key issues areclosely related to past and present socio-economic andcultural conditions, both within Prespa itself andoutside of it. The liberation of Prespa, a remote andrather socially isolated borderline area, from Ottoman occupation took place in 1912–13. Recentevents in its environmental history have been forestclearings and human depopulation in the Civil War(1944–49), irrigation system construction in the1960s, its discovery by ornithologists in the late1960s, the high emigration rates of 1960–1980, itsdesignation as a National Park in 1974, thedestructive development works of 1984–86 afterGreeces entry to the EEC and the conversion to intensivebean cultivation in the mid 1980s.The human population of ca 7000 at the start of thiscentury suffered an almost 80% decrease after theCivil War. A resettlement in the mid 1950s increasedthe population by 40% but in the 1970s emigrationreduced it to its previous size of around 1500, stillits present size. The extensive and diverse farmingsystems of previous centuries changed gradually afterthe construction of an irrigation network in the1960s, which twenty years later and along withinternational changes in production and economypatterns, made possible the present day domination ofa bean monoculture within irrigated croplands. Thiswas accompanied by increased energy inputs,mechanisation and the use of chemicals.Intensification of agriculture brought increasedincomes which attracted also livestock keepers,resulting in a 56% decrease in numbers of livestockin 1964–1993. Cattle are presently kept for meatproduction only. They graze on the mountains, and nolonger in the meadows around the lakeshore. A localshorthorn breed accounting for 93% of all cattle in1963 declined to less than 18% in 1993. Fishing aimedmainly at carp and Prespa bleak, continues today as inthe past to be a source of supplementary income.Eighty-six per cent of the – mainly oak and beech –forests are State owned and the rest belong to localmunicipalities. The forest area has not changedessentially in the last 40 years, but forest roadshave expanded. Forests provide mainly fuelwood forlocal needs and small quantities of industrial timber.No specific management is conducted to safeguard theconservation values of the forest, the majority ofwhich consists of even aged coppiced stands withlimited value for wildlife. Manufacturing never playedan important role for the economy of the area. Tourismhas increased in the last 20 years, concentratedmainly in summer and spring. Accommodation in thevillages is not yet satisfactory though it hasimproved enormously in recent years. The NationalParks infrastructure for visitors remains poor.Tourist pressure generally is not yet that high toimpact drastically the social and environmentalfabric. In places, hunting, angling and poaching cannegatively affect the target species. The constructionof the irrigation network in the eastern part of LakeMikri Prespa was the most important change to thelandscape and the habitats of Prespa the last 30years. It resulted in the embankment of free-flowingstreams, drainage of wet meadows and dramaticreduction of trees and hedges. In the last 15 years,the reedbeds, no longer burnt or mowed and assisted byincreased nutrient loadings from agricultural runoff,have expanded landward to occupy formerly open,periodically flooded, areas. The above changes inhabitats and land use have brought an impoverishmentof biodiversity which can be seen in the exterminationor the decrease in the numbers of certain plant andbird species.The problems preventing a better management of theNational Park and the perpetuation of its values areinappropriate legislation, the poor degree ofcoordination of the public services, the lack of botha specific National Park Service in Greece and amanagement authority for the Park and the hostileattitude of local people due to their limitedinformation and involvement. The scenic beauty, thewetlands and a number of rare habitats, the diversityof habitats, flora and fauna, the endemic life forms,the rare mammals and the colonial waterbirds, thelocal architecture and the cultural expressions suchas the Byzantine monuments, are the values of Prespathat must be preserved as a whole. The initialconservation efforts aimed at preserving biodiversitybut later it became apparent that not only are humansan inseparable part of the whole, but additionally,several of their extensive activities have contributedsubstantially to the rich biodiversity of the area.Through the prerequisites of keeping a balance betweenprimary and tertiary sector activities and ofrevitalizing the social fabric, the following are thekey management and conservation issues of today: anunequivocal agreement on the values to be preservedand their limits; the formation of a managementauthority; a new realistic protection and land usezoning; the diversification and extensification of allfarming activities; the restoration of the wet meadowhabitats; the ensuring of a high water level and agood water quality for both lakes through tri-lateralcooperation between Greece, Albania and FYROM; and theestablishment of a permanent environmental monitoringscheme.     

Evolution of the mitochondrial DNA control region in the mbuna (Cichlidae) species flock of lake Malawi, East Africa

Considerable controversy has surrounded the application of mitochondrial DNA data to reconstruction of evolutionary relationships among the endemic cichlids of Lake Malawi. Central to this debate has been the issue of whether lineage sorting is complete, and thus whether these data actually reflect species phylogeny, or simply gene genealogy. Review of all mtDNA control region sequences available for members of one monophyletic subset of this species flock, the Malawi rockfishes, or mbuna, strongly indicates that lineage sorting is incomplete: Character-based analyses of these sequences reconstruct gene, not species, interrelationships. Analysis of the pattern of nucleotide substitutions differentiating these mtDNA alleles suggests that pyrimidine residues undergo transition substitutions more often than do purines. Estimation of the magnitude of derived sequence differentiation in light of the reconstructed gene genealogy suggests that the mbuna may be of considerably more recent vintage than previous molecular characterizations have indicated. Received: 6 April 1996 / Accepted: 3 March 1997     

The rDNA Internal Transcribed Spacer Region as a Taxonomic Marker for Nematodes

The ITS region from a wide taxonomic range of nematodes, including secernentean and adenophorean taxa, and free-living, entomopathogenic, and plant-parasitic species, was evaluated as a taxonomic marker. Size of the amplified product aided in the initial determination of group membership, and also suggested groups that may require taxonomic reevaluation. Congeneric species often displayed identically sized ITS regions, but genera such as Pratylenchus and Tylenchorhynchus had species with large differences in size. ITS heterogeneity in individuals and populations was identified in several nematode taxa. PCR-RFLP of ITS1 is advocated as a method of taxonomic analysis in genera such as Helicotylenchus that contain numerous species with few diagnostic morphological characteristics.     

Sex estimation using the first cervical vertebra

The articular surfaces and vertebral foramen area of the first cervical vertebra are sexually dimorphic and can be used to sex complete or fragmentary specimens. Eight measurements were taken from the articular regions (superior and inferior) of 100 first cervical vertebrae from Terry collection specimens housed at the Smithsonian Institution. Seven regression and seven discriminant function equations were created that predict sex with 77–85% and 75–85% accuracy, respectively. In separate control tests, measurements from 100 first cervical vertebrae from Hamann-Todd collection individuals (Cleveland Museum of Natural History) and from 34 archaeological specimens were used with the Terry equations. The control samples were sexed with 60—85% accuracy. © 1995 Wiley-Liss, Inc.     

毛茛科金莲花亚科植物的地理分布

本文对毛茛科金莲花亚科各属的地理分布作了分析,该亚科植物除了少数属的一些种分布到南半球的温带地区,一些种分布或延伸到亚热带山地、非洲东部和北部的干旱、半干旱的地区外,绝大部分的属、种均分布于泛北极区域。根据其17个属的地理分布式样,把它们划分为8个分布区类型:(1)北温带分布类型4属;(2)北温带和非洲分布类型1属;(3)北半球温带和南半球间断分布类型1属;(4)欧洲和东亚间断分布类型1属;(5)西亚分布类型1属;(6)地中海分布类型3属;(7)欧亚和温带亚洲分布类型1属;(8)东亚分布类型5属。本文以形态特征为主,结合花粉和染色体的性状分析,认为东亚特有的鸡爪草属、Megaleranthis和铁破锣属可能分别是联系驴蹄草属和金莲花属,鸡爪草属和金莲花属以及金莲花族和升麻族的中间类型。另外,文中详细地统计了该亚科的不同等级分类群及特有种在各个植物区的分布,并从系统发育的观点讨论了各个植物区所具有的原始类群和进化类群,提出了如下论点,即东亚植物区(特别是中国西南部)不但是金莲花亚科植物分布的多度和多样性中心以及特有类群的分布中心,而且还是原始类群的保存中心,伊朗-土兰区及地中海周围是第二分布中心。     

Mammalian expression of single chain variable region fragments dimerized by Fc regions

To promote application of a single chain variable region fragment (sFv) in immunoglobulins, a sFv gene was connected to an IgG1 Fc gene, designated as a sFvc gene, and used for transfection of Sp2/0. As a result, the sFvc protein was found to be secreted in a dimeric form. It is thus felt that the sFvc protein, which mimicks the shape of a naturally occurring antibody, can be simple and useful to reproduce divalency and Fc-associated effecter functions as seen in a natural antibody.Abbreviations Abbreviations sFv single chain variable region fragment - Fc constant region of immunoglobulin - sFvc single chain variable region fragment with an Fc region