C-banding and FISH in chromosomes of the blow flies Chrysomya megacephala and Chrysomya putoria (Diptera, Calliphoridae)

The blow flies Chrysomya putoria and C. megacephala have 2n=12 chromosomes, five metacentric pairs of autosomes and an XX/XY sex chromosome pair. There are no substantial differences in the karyotype morphology of these two species, except for the X chromosome which is subtelocentric in C. megacephala and metacentric in C. putoria and is about 1.4 times longer in C. putoria. All autosomes were characterized by the presence of a C band in the pericentromeric region; C. putoria also has an interstitial band in pair III. The sex chromosomes of both species were heterochromatic, except for a small region at the end of the long arm of the X chromosome. Ribosomal genes were detected in meiotic chromosomes by FISH and in both species the NOR was located on the sex chromosomes. These results confirm that C. putoria was the species introduced into Brazil in 1970s, and not C. chloropyga as formerly described.     

Complete genome sequence of the thermophilic sulfur-reducer Hippea maritima type strain (MH(2))

Hippea maritima (Miroshnichenko et al. 1999) is the type species of the genus Hippea, which belongs to the family Desulfurellaceae within the class Deltaproteobacteria. The anaerobic, moderately thermophilic marine sulfur-reducer was first isolated from shallow-water hot vents in Matipur Harbor, Papua New Guinea. H. maritima was of interest for genome sequencing because of its isolated phylogenetic location, as a distant next neighbor of the genus Desulfurella. Strain MH(2) (T) is the first type strain from the order Desulfurellales with a completely sequenced genome. The 1,694,430 bp long linear genome with its 1,723 protein-coding and 57 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.     

鹿科动物的染色体组型及其进化

染色体是遗传物质的主要携带者。在动植物进化过程中,染色体在数量和结构上的变化,无疑对物种形成起重要的作用。染色体的变化往往引起基因的重新排列和遗传物质的增加或丢失。染色体在结构和数量上的差异还往往造成两个本来很相近的群体间的生殖隔离而形成新种。染色体组型和染色体的带型都代表着种的特性,它为不同动物在分类研究和确定其在进化过程中的位置提供了一个新的和重要的标准。可是,染色体的结构既是稳定的,同时又是可变的。染色体组型的改变是以染色体组的结构特点为基础     

山东海岸木生海洋真菌的研究I.(英文)

为调查中国黄海海域的丝状海洋真菌,从山东威海潮间带海滩收集了沉没木、附着木和沙埋木,并从其上分离到7种高等海洋真菌。Arenariomycestrifurcata,Corollosporamaritima,Alternariamaritima,Trichocladiumachrasporum为中国大陆新记录种,Chaetomiunglobosum,Tetraploaaristata,Torulasp.为中国大陆新生境报道。对每个种作了描述并对分类和形态进行了讨论。     

Pollen and seed morphology of Gueldenstaedtia and Tibetia (Leguminosae) - with a special reference to the taxonomic significance

The pollen morphology of Gueldenstaedtia gansuensis. G. gracilis, G. henryi, G. monophylla. G. mutijlora, G. stenophylla. and G. verna and Tibetia liangshanensis, T. tongolensis, T. yadongensis. T. coelestis, and T yunnanensis are reported for the first time. The seed morphology of G. gracilis, G. maritima. G. monophylla, G. mutiflora, G. taihangensis, and G. verna and L coelestis, T. himalaica, T. yunnanensis, and T. yadongensis are firstly described here. In pollen morphology, the differences of pollen grains of Gueldenstaedtia and Tibetia are as follows: Gueldenstaedtia with pollen grains 3–colporate, psilate, and shapes spheroidal, sometimes subprolate, prolate or oblong; and Tibetia with pollen grains 3– and 4–colporate, perforate, shapes spheroidal, sometimes subprolate or prolate. These results, combined with the data of the basic chromosome number x=7 of Gueldenstaedtia and x=8 of Tibetia, support that the two genera should be recognized as two distinct genera, which are consistent with their morphological characters: Gueldenstaedtia with 2 upper lobes of calyx free, stipules free, adnate to petiole, and Tibetia with 2 upper lobes of calyx connate, stipules connate and opposite to leaves. In Tibetia, two types of pollen grains, 3– and 4–colporate pollen grains, are found. Regarding seed morphology: Gueldenstaedtia has circular depression, irregular circular depression or irregular circular reticulation on the surface; Tibetia has smooth surface. The differences in seed morphology of the two genera also support that they should be kept separate. The pollen morphology supports that G. gansuensis, G. gracilis, G. multiflora, G. stenophylla, and G. verna should be reduced into one species consistent with their morphological characteristics. The pollen grains of G. henryi are different from those of the other species in having wide colpi.     

X-chromosomal localization of mammalian Y-linked genes in two XO species of the Ryukyu spiny rat

Ryukyu spiny rats (genus Tokudaia), which are endemic to the central part of the Nansei Shoto archipelago in Japan, have unique karyotypes with odd numbers of chromosomes and no cytologically recognizable Y chromosome. The chromosome numbers of Tokudaia osimensis from Amamioshima and of Tokudaia sp. from Tokunoshima are 2n = 25 and 2n = 45, respectively, with a putative single X chromosome. The mouse X probe hybridized to the unpaired X chromosome, except for the distal part of the short arm in a female specimen of T. osimensis and in one male and one female of Tokudaia sp. Fluorescence in situ hybridization with the Tspy (testis-specific protein, Y-encoded) gene from both male and female cells of Tokudaia sp. by PCR localized Tspy to the distal part of the long arm of the X chromosome. Another Y-related gene, Zfy, from Tokudaia sp. was also localized to the same region in both species. Although the Sry gene is absent in this species, the present results suggest that the Y-chromosome segment carrying functional Y-linked genes, such as Tspy and Zfy, is translocated onto the distal part of the long arm of the X chromosome.     

Coexistence of two related bush-cricket species (Orthoptera: Tettigonia caudata, T. viridissima) in an agricultural landscape

Competition is a basic type of interaction between species. Because complete competitors cannot exist in one habitat, closely related species must show at least slight differences in their biology or ecology. In the present study, we analyzed the habitat use of the two closely related bush-cricket species Tettigonia caudata and T. viridissima which often occur syntopically. The meso- and microhabitat use of males was compared in an agricultural landscape in NE Germany. Males of both species were found to use similar mesohabitats and to prefer dense and high vegetation. Microhabitats differed significantly in two aspects: Microhabitats of T. caudata had a higher proportion of herbs, while T. viridissima used higher song posts. These differences in microhabitats might explain the co-occurrence of the bush-crickets in open habitats. However, variation between the two species might also take place during other life-cycle stages such as during egg development.     

Chromosome evolution in the Thermotogales: large-scale inversions and strain diversification of CRISPR sequences

In the present study, the chromosomes of two members of the Thermotogales were compared. A whole-genome alignment of Thermotoga maritima MSB8 and Thermotoga neapolitana NS-E has revealed numerous large-scale DNA rearrangements, most of which are associated with CRISPR DNA repeats and/or tRNA genes. These DNA rearrangements do not include the putative origin of DNA replication but move within the same replichore, i.e., the same replicating half of the chromosome (delimited by the replication origin and terminus). Based on cumulative GC skew analysis, both the T. maritima and T. neapolitana lineages contain one or two major inverted DNA segments. Also, based on PCR amplification and sequence analysis of the DNA joints that are associated with the major rearrangements, the overall chromosome architecture was found to be conserved at most DNA joints for other strains of T. neapolitana. Taken together, the results from this analysis suggest that the observed chromosomal rearrangements in the Thermotogales likely occurred by successive inversions after their divergence from a common ancestor and before strain diversification. Finally, sequence analysis shows that size polymorphisms in the DNA joints associated with CRISPRs can be explained by expansion and possibly contraction of the DNA repeat and spacer unit, providing a tool for discerning the relatedness of strains from different geographic locations.     

Effects of thermoperiod on recovery of seed germination of halophytes from saline conditions

Recovery of seed germination from NaCl salinity of desert shrubs (Haloxylon recurvum and Suaeda fruticosa, and the herbs Zygophyllum simplex and Triglochin maritima was studied under various thermoperiods. The percentage of ungerminated seeds that recovered when they were transferred to distilled water varied significantly with variation in species and thermoperiods. Zygophyllum simplex had little recovery from all NaCl concentrations in all thermoperiods. Haloxylon recurvum, S. fruticosa, and T. maritima showed substantial recovery. Percentage recovery was highest in S. fruticosa, followed by T. maritima, and H. recurvum. Thermoperiodic effects varied with the species investigated. There was little thermoperodic effect on the percentage recovery of S. fruticosa, except in the higher salinity treatment at higher thermoperiods. Variation in thermoperiod appears to play an important role in recovery of germination of halophytes from salt stress when seeds are transferred to distilled water.     

Comparative cytogenetics of tapirs, genus tapirus (Perissodactyla, tapiridae)

Chromosomes of the four species of Tapirus were 2n = 52 in T. indicus, 2n = 76 in T. pinchaque, 2n = 80 in T. bairdii, and 2n = 80 in T. terrestris. The number of autosomal arms was 80-94. G-banded karyotypes indicated that a heterochromatic addition/deletion distinguished chromosomes 2 and 3 of T. bairdii and T. pinchaque, respectively. There were at least 13 conserved autosomes between the karyotypes of T. bairdii and T. terrestris, and at least 15 were conserved between T. bairdii and T. pinchaque. In G- and C-banded preparations, the X chromosomes of T. bairdii, T. indicus, and T. terrestris were identical, whereas the X chromosome of T. pinchaque differed from the X of the other species by a heterochromatic addition/deletion. The Y chromosome was a medium-sized to small acrocentric in T. bairdii, T. indicus, and T. pinchaque, but it was not positively identified in T. terrestris. There appeared to be fewer homologies between T. indicus and the three species occurring in Central and South America. Future cytogenetic studies of tapirs from the entire range of each of the four species might provide additional insight into their evolutionary biology and aid wildlife conservation efforts aimed at these threatened mammals.     

Chromosomal distribution of repetitive DNA sequences highlights the independent differentiation of multiple sex chromosomes in two closely related fish species

The arrangement of 6 repetitive DNA sequences in the mitotic and meiotic sex chromosomes of 2 Erythrinidae fish, namely Hoplias malabaricus and Erythrinus erythrinus, both with a multiple X(1)X(1)X(2)X(2)/X(1)X(2)Y sex chromosome system, was analyzed using fluorescence in situ hybridization. The distribution patterns of the repetitive sequences were distinct for each species. While some DNA repeats were species-specific, others were present in the sex chromosomes of both species at different locations. These data, together with the different morphological types of sex chromosomes and the distinct chromosomal rearrangements associated with the formation of the neo-Y chromosomes, support the plasticity of sex chromosome differentiation in the Erythrinidae family. Our present data highlight that the sex chromosomes in fish species may follow diverse differentiation patterns, even in the same type of sex chromosome system present in cofamiliar species.     

Cytogenetic evidence for a complex of species within the taxon Anopheles maculatus (Diptera: Culicidae)

Two largely independent studies of chromosomes from natural populations of Anopheles maculatus provide evidence for several genetic species within the taxon. (1) Polytene chromosome variation shows four different rearrangements of arm 2 and three rearrangements of the X chromosome. There is strong evidence for three species. Two allopatric populations represent either dramatic geographic variation for two independent inversion systems within one of the genetic species, or represent two additional species. Their species status remains unresolved by this work. (2) Heterochromatic variation occurs in both X and Y chromosomes as revealed by Giemsa-banding of mitotic chromosomes from larval brains. The distribution and association of these various sex chromosomes give further evidence of a species complex. A preliminary correlation of these two kinds of chromosomal variation is given.     

Interaction of B chromosomes with A or B chromosomes in segregation in insects

Additional or B chromosomes not belonging to the regular karyotype of a species are found in many animal and plant groups. They form a highly heterogeneous group with respect to their morphology and behaviour both in mitosis and meiosis. Achiasmatic mechanisms that ensure the segregation of a B chromosome from another B chromosome or from an A chromosome are reviewed. An achiasmatic mechanism characterized by the "distance pairing" of segregating univalents at metaphase I was found to be responsible for the preferential segregation of B chromosome univalents in Hemerobius marginatus L. (Neuroptera), and a mechanism characterized by the "touch and go pairing" of segregating univalents was responsible for the highly regular segregation of a B chromosome and the X chromosome in Rhinocola aceris (L.) (Psylloidea, Homoptera). The latter mechanism resulted in the integration of a B chromosome to the A chromosome set as a Y chromosome in a psyllid species Cacopsylla peregrina (Frst.). Furthermore, B chromosomes can disturb the regular segregation of the achiasmatic X and Y chromosomes resulting in the formation of X0/XY polymorphism in a population, which might precede the loss of the Y chromosome. The absence of observations on accurately functioning achiasmatic segregation mechanisms in grasshoppers (Orthoptera) was attributed to the X and B chromosomes, which re-orient one or several times during metaphase I. Apparently, these re-orientations mask any achiasmatic segregation mechanism that might operate during meiotic prophase in these insects.     

GTPase activity, structure, and mechanical properties of filaments assembled from bacterial cytoskeleton protein MreB

MreB, a major component of the recently discovered bacterial cytoskeleton, displays a structure homologous to its eukaryotic counterpart actin. Here, we study the assembly and mechanical properties of Thermotoga maritima MreB in the presence of different nucleotides in vitro. We found that GTP, not ADP or GDP, can mediate MreB assembly into filamentous structures as effectively as ATP. Upon MreB assembly, both GTP and ATP release the gamma phosphate at similar rates. Therefore, MreB is an equally effective ATPase and GTPase. Electron microscopy and quantitative rheology suggest that the morphologies and micromechanical properties of filamentous ATP-MreB and GTP-MreB are similar. In contrast, mammalian actin assembly is favored in the presence of ATP over GTP. These results indicate that, despite high structural homology of their monomers, T. maritima MreB and actin filaments display different assembly, morphology, micromechanics, and nucleotide-binding specificity. Furthermore, the biophysical properties of T. maritima MreB filaments, including high rigidity and propensity to form bundles, suggest a mechanism by which MreB helical structure may be involved in imposing a cylindrical architecture on rod-shaped bacterial cells.     

Local variability of the phosphoglycerate kinase-triosephosphate isomerase fusion protein from Thermotoga maritima MSB 8

The pgk-tpi gene locus of Thermotoga maritima encodes both phosphoglycerate kinase (PGK) and a bienzyme complex consisting of a fusion protein of PGK with triosephosphate isomerase (TIM). No separate tpi gene for TIM is present in T. maritima. A frame-shift at the end of the pgk gene has been previously proposed as a mechanism to regulate the expression of the two protein variants [Schurig et al., EMBO J. 14 (1995), 442-451]. Surprisingly, the complete T. maritima genome was found to contain a pgk-tpi sequence not requiring the proposed frameshift mechanism. To clarify the apparent discrepancy, a variety of DNA sequencing techniques were applied, disclosing an anomalous local variability in the pgk-tpi fusion region. The comparison of different DNA samples and the mass spectrometric analysis of the amino acid sequence of the natural fusion protein from T. maritima MSB8 confirmed the local variability of the DNA variants. Since not all peptide masses could be assigned, further variations are conceivable, suggesting an even higher heterogeneity of the T. maritima MSB8 strain.     

青海四种雏蝗染色体核型的比较分析

采用常规染色体制片方法对雏蝗属的褐色雏蝗Chorthippusbrunneus(Thunb .) ,异色雏蝗C .big uttulus(Linnaeus) ,小翅雏蝗C .fallax(Zub .) ,青藏雏蝗C .qingzangensis(Ying)的染色体核型进行分析 ,结果 :染色体数目均为 2n(♂ ) =1 7=1 6+XO ;常染色体类型为两类 ,中着丝点染色体 (m ,6条 )和端着丝点染色体 (T ,1 0条 ) ;性染色体类型为端着丝点。褐色雏蝗、异色雏蝗和青藏雏蝗的核型公式和染色体的相对长度组成为K( 2n ,♂ ) =1 7=6m +1 1T =6L +6M +4S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +6M +4S +XX ;小翅雏蝗的为K( 2n,♂ ) =1 7=6m +1 1T =6L +4M +6S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +4M +6S+XX。褐色雏蝗性染色体中部有次缢痕。染色体臂数 4种均为NF =2 3(♂ ) ,2 4 (♀ )。     

鲤科七种鱼的银染核型研究

对鲤科七种鱼的银染核型进行了比较研究。这七种鱼均有4个NORs。其中鲴亚科五种鱼的Ag-NORs彼此特征相似;鮈亚科的似刺鳊鮈sm_3染色体上的NORs与次缢痕的位置、形态一致;雅罗鱼亚科的鳡鱼sm_6同源染色体上的一对NORs显示相对大小异形。结合以前的工作,本文以NORs为指标,讨论了有关雅罗鱼亚科几种鱼的亲缘关系及亚科鱼类染色体进行保守等问题。     

SOUND PRODUCTION AND SOUND EMISSION IN SEVEN SPECIES OF EUROPEAN TETTIGONIIDS. PART I. THE DIFFERENT PARAMETERS OF THE SONG; THEIR RELATION TO THE MORPHOLOGY OF THE BUSHCRICKET

Abstract

Comparative studies of sound production and sound emission in seven species of European tettigoniids have been carried out. The species chosen were two Tettigoniines (Tettigonia cantans, Tettigonia viridissima), two Ephippigerines (Ephippiger discoidalis, Ephippiger ephippiger), and three Decticines (Decticus albifrons, Decticus verrucivorus, Psorodonotus illyricus). The factors which determined the choice of species were the different morphology (for example body shape and weight, and wing size) of the three subfamilies. The parameters of the different songs (e.g. dominant frequency, intensity) are normally not correlated to any of the investigated morphological characteristics of the animals. In the brachypterous species intraspecific correlations exist between wing size and the dominant low frequency band of the call. This frequency band is also observable at related higher frequencies in the ultrasonic range (20–60 kHz), the observed band width increasing with frequency. Sound emission in all species is to some extent directional. This directionality is related to body size and wing structure. The song structure of the different species does not appear to be related to any observable characteristic of the habitat of die animals. A possible exception may be the song of Psorodonotus illyricus with a particularly low dominant frequency band. The phylogenetic development of the songs seems to be determined by relationships between the different species rather than to any factors contributed by the habitat.