Ultrastructure of Chrysopetalid Paleal Chaetae (Annelida,Polychaeta)

Paleal notochaetae belonging to a number of Chrysopetalum species (Chrysopetalidae) were examined by scanning and transmission electron microscopy. Paleae are composed of broad medullary channels stacked with a regular series of horizontal fibrous diaphragms. The medullary part of the palea is surrounded by irregular rows of narrow tubular channels within the chaetal cortex. The origin and function of camerate chaetae is discussed.     

Genetic and chaetal variation in Nais worms (Annelida,Clitellata, Naididae)

The genus Nais is a group of oligochaetous clitellates, common in eutrophic freshwater habitats. About 30 species are described. Species identification is based primarily on chaetal characters, which are often subtle, inconsistent, and even overlapping between nominal species. We investigated the correlation between genetic variation and chaetal morphology in this genus. Eighty‐one individuals from Europe, North America, and China were included in the study. Seventy‐five of these were preserved as vouchers. They were scrutinized with regard to chaetal morphology, and ten different morphotypes were identified. Three molecular markers, two mitochondrial (the COI gene and 16S rDNA) and one nuclear (the ITS region), were used to establish the genetic lineages in the material. Genetic variation was found to be largely congruent with chaetal character patterns. However, at least nine separately evolving lineages (all supported by mitochondrial as well as nuclear data) correspond to at most six nominal species. Four morphotypes/lineages are recognized as Nais barbata, Nais christinae, Nais elinguis, and Nais stolci, respectively, whereas five, or possibly more, lineages represent a morphological continuum covering the variation of the Nais communis/variabilis complex. Thus, cryptic speciation is revealed. Our results indicate that a taxonomic revision of the genus will be needed in the future.     

Chaetal arrangement in Orbiniidae (Annelida,Polychaeta) and its significance for systematics

The systematic position of Orbiniidae within Polychaeta is still uncertain. In order to provide additional comparative data, we investigated the chaetal arrangement in this family, which is considered valuable for polychaete systematics. Specimens of Scoloplos armiger, Orbinia latreillii, and Pettibonella multiuncinata were examined by SEM and serial sections analysed by computer aided 3D-reconstructions. The obtained data suggest that the chaetal arrangement of Orbiniidae resembles that of other sedentary polychaetes in only a few respects. Transverse rows are only present in the main, anterior part of the chaetal patches of thoracic neuropods. The position of the formative site indicates homology with the transverse rows of several sedentary polychaete taxa. The chaetal patches thus differ significantly from those known in Apistobranchidae. Independent rows with an own caudal formative site, which run along the caudoventral edge of the chaetal patches, resemble the neuropodial ventral longitudinal rows known in Spionidae and related taxa. The abdominal neuropodia of S. armiger and O. latreillii bear longitudinal rows of chaetae. These are reorientated during ontogenetic chaetiger transformation and become the transverse rows of the thoracic chaetal patches. 3D reconstruction of S. armiger revealed that the notopodial chaetal bundles are organized in rows as well. Notopodia and abdominal neuropodia bear deep reaching supportive chaetae. They are the first chaetae formed during neuropodial development and reside dorsally to the longitudinal row of capillary chaetae. Neither position nor structure indicates homology with the supportive chaetae of other sedentary polychaetes. Spionidae and related taxa are thus the only sedentary polychaetes, which specifically resemble Orbiniidae in certain aspects of their chaetal arrangement. Dedicated to Prof. Dr. Wilfried Westheide on the occasion of his 70th birthday.     

Homology and Evolution of the Chaetae in Echiura (Annelida)

Echiura is traditionally regarded as a small phylum of unsegmented spiralian worms. Molecular analyses, however, provide unquestionable evidence that Echiura are derived annelids that lost segmentation. Like annelids, echiurans possess chaetae, a single ventral pair in all species and one or two additional caudal hemi-circles of chaetae in two subgroups, but their evolutionary origin and affiliation to annelid chaetae are unresolved. Since annelids possess segmental pairs of dorsal (notopodial) and ventral (neuropodial) chaetae that are arranged in a row, the ventral chaetae in Echiura either represent a single or a paired neuropodial group of chaetae, while the caudal circle may represent fused rows of chaetae. In annelids, chaetogenesis is generally restricted to the ventral part of the notopodial chaetal sac and to the dorsal part of the neuropodial chaetal sac. We used the exact position of the chaetal formation site in the echiuran species, Thalassema thalassemum (Pallas, 1766) and Echiurus echiurus (Pallas, 1767), to test different hypotheses of the evolution of echiurid chaetae. As in annelids, a single chaetoblast is responsible for chaetogenesis in both species. Each chaeta of the ventral pair arises from its own chaetal sac and possesses a lateral formation site, evidencing that the pair of ventral chaetae in Echiura is homologous to a pair of neuropodia that fused on the ventral side, while the notopodia were reduced. Both caudal hemi-circles of chaetae in Echiurus echiurus are composed of several individual chaetal sacs, each with its own formative site. This finding argues against a homology of these hemi-circles of chaetae and annelids’ rows of chaetae and leads to the hypothesis that the caudal chaetal rings evolved once within the Echiura by multiplication of ventral chaetae.     

Two new species of an atypical group of Pseudobranchiomma Jones (Polychaeta: Sabellidae)

The genus Pseudobranchiomma Jones, 1962 can be divided into three groups: (A) those with paired serrated flanges along all or most of the crown radioles, as in the type species P. emersoni Jones, 1962; (B) those with such flanges only on the distal parts of the radioles; (C) those with flanges reduced or absent (without serrations) as in two new species described here from Florida and Italy. Group C also contains Pseudobranchiomma longa (Kinberg, 1867), P. punctata (Treadwell, 1906) and P. minima (Nogueira & Knight-Jones, 2002). Lists of species (and their synonyms) in the other two groups are given, and scissiparity, thoracic length, chaetal arrangements and types of radiolar eyes are discussed.     

Cytotaxonomical analysis of <Emphasis Type="Italic">Momordica</Emphasis> L. (Cucurbitaceae) species of Indian occurrence

Somatic chromosome number and detailed karyotype analysis were carried out in six Indian Momordica species viz. M. balsamina, M. charantia, M. cochinchinensis, M. dioica, M. sahyadrica and M. cymbalaria (syn. Luffa cymbalaria; a taxon of controversial taxonomic identity). The somatic chromosome number 2n = 22 was reconfirmed in monoecious species (M. balsamina and M. charantia). Out of four dioecious species, the chromosome number was reconfirmed in M. cochinchinensis (2n = 28), M. dioica (2n = 28) and M. subangulata subsp. renigera (2n = 56), while in M. sahyadrica (2n = 28) somatic chromosome number was reported for the first time. A new chromosome number of 2n = 18 was reported in M. cymbalaria against its previous reports of 2n = 16, 22. The karyotype analysis of all the species revealed significant numerical and structural variations of chromosomes. It was possible to distinguish chromosomes of M. cymbalaria from other Momordica species and also between monoecious and dioecious taxa of the genus. Morphology and crossability among the dioecious species was also studied. Evidence from morphology, crossability, pollen viability and chromosome synapsis suggests a segmental allopolyploid origin for M. subangulata subsp. renigera. The taxonomic status of the controversial taxon M. cymbalaria was also discussed using morphological, karyological and crossability data.     

Recent genus Notonecta (Insecta: Heteroptera: Notonectidae) in the Lower Cretaceous of San Luis,Argentina: Palaeoecological implications

We describe a new species of the genus Notonecta, i.e. Notonecta mazzoniae n. sp. from the Lower Cretaceous of Argentina. It is the first fossil representative of the family described from South America, demonstrating the great antiquity of the genus, bearing identical ventral chaetal system correlated with respiratory for such a long period. The new species is recorded only by immature stages from the second to the fifth instars. Specimens are considered to be exuviae and not body fossils. Absence of body fossils may be due to taphonomic bias instead of palaeoecological constrains. In addition we found some specimens of Anisopinae, also considered as nymph exuviae, which represent the oldest record of the taxon.     

A new genus of Syllidae (Polychaeta) from Western Australia

During a study carried out on the subfamily Exogoninae (Syllidae) from Australia, several specimens of a new genus and species were found in samples of dead coral substrate from Western Australia. They have long palps, fused except for a terminal notch, long median and two short lateral antennae, a single pair of short tentacular cirri, and short dorsal cirri, somewhat longer than the parapodial lobes. These characters resemble those of the genus Exogone Örsted, 1845. However, all these appendages are articulated. The chaetae are very similar to those of several species of Syllis Lamarck, 1818, having coarse spines on the margin of compound chaetal blades and truncated dorsal simple chaetae. Furthermore, the pharynx begins in chaetiger 3, posterior to the peristomium, as in many species of the genus Syllis; this condition does not occur in any described species of Exogone. The new genus is provisionally proposed to belong to the subfamily Syllinae, although it has some characters typical of the Exogoninae. Examination under the SEM shows another peculiar feature, the nuchal organs are distinctly laterally located. Within the Syllinae, only Paratyposyllis Hartmann-Schröder, 1962 has a single pair of tentacular cirri, but in that genus, the palps are only basally fused.     

三种厚朴叶绿体基因组的比较研究

为了深入发掘日本厚朴、厚朴、凹叶厚朴叶绿体基因组差异,筛选厚朴优良性状候选基因,开展三种厚朴的分子遗传研究,该文利用Illumina HiSeq高通量测序平台首次对日本厚朴叶绿体进行测序、组装,并与已有的厚朴、凹叶厚朴叶绿体基因组共同注释,获得三个物种叶绿体基因图谱,筛选出三个基因组中的差异基因,又与同科中11个亲缘物种进行叶绿体基因组比对,构建NJ遗传树。结果表明：(1)日本厚朴叶绿体基因组的Clean Reads为19 791 019,Q30为91.33%,组装后基因组全长160 051 bp, GC含量为39.2%,含tRNA 37个,rRNA 8个。(2)比对分析发现三种厚朴具有相似的IR、LSC和SSC结构,以及GC含量和tRNA数量,但编码基因种类和数量、内含子和外显子的数量和结构等存在差异。(3)日本厚朴的功能基因数目较厚朴、凹叶厚朴分别多6个和4个,主要分布于LSC区和IR区,涉及核糖体大亚基、核糖体小亚基和未知功能基因类群。(4)系统发育分析结果进一步显示日本厚朴与凹叶厚朴亲缘关系较近,其次是厚朴。该研究表明日本厚朴具有更丰富的叶绿体基因组结构、组成和变异特征,是其适...     

Hair today,gone tomorrow: induced chaetal changes in tubificid oligochaetes

Laboratory experiments were conducted to determine the extent of chaetal variation in the tubificids Tubifex tubifex and Ilyodrilus frantzi and the naidids Specaria fraseri and Nais communis under varying environmental conditions. Univariate exposures were carried out using different levels of pH, salinity, water hardness and mercury. We were not able to induce chaetal changes in the two naidids tested. However, we were able to reduce the hairs and pectinations of T. tubifex with exposure to pH, salinity and to hard water such that the bergi form was produced. Prolonged exposure to low or high pH resulted in the total loss of hairs and pectinates such that the blanchardi form was produced. We were able to eliminate the hairs and pectinates of I. frantzi (capillatus) in soft, freshwater exposures such that the bifidus form of I. frantzi was produced. Conversely, in hard or saline water we were able to induce formation of hairs and pectinates on the bifidus form such that the capillatus form was produced. These changes occurred at time intervals ranging from a few days to two months.     

Comparison of K+-channel activation and deactivation in guard cells from a dicotyledon (Vicia faba L.) and a graminaceous monocotyledon (Zea mays)

We describe and compare inward and outward whole-cell K⁺ currents across the plasma membrane surrounding guard-cell protoplasts from the dicotyledon, Vicia faba, and the graminaceous monocotyledon, Zea mays. Macrosopic whole-cell current is considered in terms of microscopic single-channel activity, which involves discrete steps between conducting (open) and nonconducting (closed) states of the channel protein. Kinetic equations are used to model the number of open and closed states for channels conducting K⁺ influx (K(in)) and K⁺ efflux (K(out)) in the two species, and to calculate the rate at which open-closed transitions occur. The opening and closure of K(in) channels in both Vicia and Zea follow single-exponential timecourses, indicating that K(in)-channel proteins in each species simply fluctuate between one open and one closed state. In both species, opening of K(in) channels is voltage-independent, but closure of K(in) channels is faster at more positive membrane potentials. In response to identical voltage stimuli, K(in) channels in Zea open and close approximately three times as fast as in Vicia. In contrast to K(in), K(out) channels in Zea open and close more slowly than in Vicia. The closure of K(out) channels follows a single-exponential timecourse in each species, indicating one open state. The kinetics of K(out)-channel opening are more complicated and indicate the presence of at least two (Vicia) or three (Zea) closed states. The authors thank Professor N.A. Walker and Dr. D.R. Laver for the use of laboratory equipment, for helpful discussion and for provision of the program, GETHH. Thanks also to Dr. R.J. Ritchie for assistance with statistical analyses and to Ms. Janet Sherwood for maintenance of Vicia and Zea plants. This work was supported by grants from the National Science Foundation (DCB-89-04041) and the McKnight Foundation (S.M.A) and by a Charles Gilbert Heydon Travelling Fellowship (K.F-G).     

Different egg-associated and larval development characteristics of Macrobrachium jelskii and Macrobrachium amazonicum (Arthropoda: Crustacea) in a Venezuelan continental lagoon

Summary

In Venezuela, M. jelskii and M. amazonicum are both found living in fresh waters and sometimes share the same habitat. The respective patterns of development of the two species have been compared, with reference to such parameters as egg size and number, duration and number of larval stages, and body length of the first zoea. Development of M. jelskii exhibits features characteristic of fresh water species, whereas that of M. amazonicum has features usually associated with brackish water species.     

Microsatellite markers for the large blue butterflies Maculinea nausithous and Maculinea alcon (Lepidoptera: Lycaenidae) and their amplification in other Maculinea species

We developed microsatellite markers for Maculinea nausithous and Maculinea alcon, two of five species of endangered large blue butterflies found in Europe. Two separate microsatellite libraries were constructed. Eleven markers were developed for M. nausithous and one for M. alcon. The primers were tested on both species as well as on the three other European Maculinea species. The number of alleles per locus ranged from two to 14. These markers will be useful tools for population genetic studies of Maculinea species.     

我国原生植物假泽兰(菊科)的细胞学研究

该文研究了我国原生植物假泽兰(Mikania cordata)台湾花莲居群、苗栗居群、宜兰居群以及台北居群的染色体数目和染色体形态。结果表明:所有居群的染色体数目为2n=36,第一对染色体为近中部着丝粒染色体,其长臂中部具有次缢痕,显著大于其余染色体。各居群的核型公式皆为2n=18m+18sm,核型均为2B型,染色体内不对称性指数(A_1)的变化范围为0.38~0.39,染色体之间不对称性指数(A_2)的变化范围为0.30~0.32。此为我国假泽兰居群染色体数目的唯一报道,也是对该种核型的首次报道。结合前人对假泽兰染色体数目的研究结果,认为假泽兰存在种内非整倍性现象,但在中国台湾的居群中目前仅发现基于x=18的二倍体(2n=36)。假泽兰的第一对染色体的长臂中部具次缢痕,与假泽兰属已报道的核型相似,这一次缢痕可作为假泽兰属的细胞学标记。核型资料、野外观察以及ISSR数据显示薇甘菊(M.micrantha)在我国的成功入侵与入侵种和本土种之间的杂交渐渗无关。根据标本记录和野外考察结果,我国假泽兰现在的分布区与过去相比有了很大的缩减,推测生境的破坏和薇甘菊的侵入可能是导致假泽兰在中国台湾地区逐渐消失的主要原因。     

Karyomorphology of Maianthemum sensu lato (Polygonatae, Ruscaceae)

We report results of karyotype analyses using nine species of Maianthemum from China. The species, except M. atropurpureum (with 2n=72), had 2n=36, and the results support the earlier suggestion that Maianthemum has x=18 with 2n=36 in most species. The species examined, however, showed marked differences in karyotype, particularly in the numbers of metacentric, submetacentric, and acrocentric chromosomes as well as in the number of satellites. In addition, we distinguished three different modes based on the number of clear gaps in chromosome length variation: unimodal, bimodal, and trimodal. The unimodal variation (with no gap) was found in M. dahuricum and M. atropurpureum, the bimodal variation (with one gap) in M. tatsienense, and the trimodal variation (with two gaps) in M. bifolium, M. forrestii, M. japonicum, M. henryi, M. purpureum, and M. lichiangense. In the trimodal variation, the positions of the two gaps may differ from species to species. In addition, the frequency of acrocentric chromosomes per complement was generally higher in the trimodal variation than in the unimodal and bimodal variations. Results of our analyses, which had not been clearly presented prior to this, may provide a better understanding of species evolution in the tribe Polygonatae.     

Mycobacterium rhodesiae sp. nov.

A number of rapid-growing scotochromogenic mycobacteria were isolated from the sputum specimen of Rhodesian patients with pulmonary disease and recognized as a new species. This was given the name Mycobacterium rhodesiae sp. nov. A comparison between M. rhodesiae, M. parafortuitum, M. aurum and M. vaccae was done, and distinguishing characters serving for differentiation between these 4 species of rapid-growing scotochromogenic mycobacteria were described.     

Altitudinal distribution of bats in the Pol’ana Mts area (Central Slovakia)

In May — August, bats were mist-netted along an altitudinal gradient of 350–1350 m a.s.l. in the Pol’ana Mts area, to verify the correlation of species number decrease and the increase in elevation, to find which species could be predictors of certain altitude levels and to compare the sexual occurrence of species in various altitudes. Seventeen bat species were recorded. The most abundant mist-netted species were Myotis daubentonii (16%), M. myotis (13%) and M. mystacinus (12%). Otherwise, the most frequently caught species were M. mystacinus (40%), Eptesicus serotinus, M. myotis (26%) and Nyctalus leisleri (23%). In this study at a local scale, from oak to spruce vegetation stages, decreasing number of species with increasing altitude was found. Species dominance of the individual altitudinal levels was significantly different (15 species up to 600 m a.s.l., six species over 1100 m a.s.l.). The results indicated that the occurrence of some bat species, due to their ecological adaptations, is more or less characteristic for higher or lower altitudes of the Western Carphathians. The “lowland” species were considered to be mainly E. serotinus, Pipistrellus pipistrellus, N. noctula, N. leisleri and M. daubentonii. In higher elevations (more than 850 m), the presence of reproductive females was not found, of all but one, N. noctula, of the “lowland” species which are breeding in the area. The “mountain” species were considered to be E. nilssonii and Plecotus auritus. The general occurrence and reproduction of M. mystacinus and Barbastella barbastellus, was not limited by elevation.     

Effects of river control structures on the juvenile migration of Macrobrachium ohione

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