This paper describes a new diatom species, Aulacoseira calypsi Tremarin, Torgan & Ludwig, from specimens in plankton samples from Água Preta lake. This Amazonian lake is a shallow mesotrophic environment situated in northern Brazil. The species is characterized by long filaments united by spatulate linking spines, obovate to conic separation spines, a valve surface variably ornamented, straight striae on the mantle, a narrow ringleist, and one row of sessile rimoportulae near the ringleist. Aulacoseira calypsi's morphometric features are compared with the following similar species: Aulacoseira nygaardii (Camburn) Camburn & Charles, Aulacoseira lacustris (Grunow) Krammer, Aulacoseira coroniformis Pearce & Cremer, Aulacoseira occulta Siver & Hamilton, Aulacoseira lancea Siver & Hamilton, Aulacoseira gessneri (Hustedt) Simonsen, and Aulacoseira islandica (Müller) Simonsen. The species shares similarities as to frustule size, striation pattern, and narrowness of ringleist; but differs in the morphology of separation and linking spines, and the number and position of the rimoportulae. 相似文献
Aulacoseira skvortzowii sp. nov. is a diatom taxon present in modern plankton assemblages and sedimentary deposits from Lake Baikal, Russia. It has been previously reported as A. islandica (O. Müll.) Simonsen, A. islandica ssp. helvetica (O. Müll.) Simonsen, a sporangial frustule of A. baicalensis (K. Meyer) Simonsen, and Aulacoseira “spore”. However, its microstructure, ecology, and ability to form true resting spores provide ample criteria to describe this diatom as Aulacoseira skvortzowii sp. nov. 相似文献
Are size and arrangement of valve mantle areolae in Aulacoseira Thwaites adapted to light intensity? To test one criterion demonstrating an adaptation, heritability experiments were run on isolates of Aulacoseira subarctica (Müller) Haworth. Several clones of A. subarctica were isolated from Yellowstone Lake (Wyoming, USA), Lewis Lake (Wyoming), and East Rosebud Lake (Montana, USA). Two to four clones from each lake were grown in batch cultures under three irradiance levels: 2, 11.4, and 115 μmol photons·m?2·s?1. Five randomly chosen valves for each of two replicates of each clone were examined using a scanning electron microscope for a total of 300 valves. Size measurements were taken for each valve examined, and images of mantle areolae were captured on film at a magnification of 20,000×. Each image was digitized, and quantitative morphometric areolar characters were measured. A quantitative genetic analysis was performed within each light environment for the mean area of the external opening of mantle areolae, the mean distance between areolae within pervalvar striae, and the mean distance between pervalvar striae. Resulting estimates of heritability from among‐lake and within‐lake analyses indicate that all three mantle areolar characters could presently respond to selection and thus have potentially done so in the past. 相似文献
Molecular studies conducted over the past 25 years have revealed previously unrecognised diversity in the phylum Acanthocephala.
Several nominal species have been shown to represent complexes of morphologically cryptic biological species, a situation
potentially confounding the analysis of ecological data. A software tool, ‘Proboscis profiler’, was developed to detect morphological
heterogeneity in collections of superficially similar acanthocephalan worms based on the multivariate statistical analysis
of proboscis hook dimensions. Proboscis profiler identifies objective, natural groups in a collection of acanthocephalans
which may correspond to distinct biological species or populations. Initial trials demonstrate that Proboscis profiler can
discriminate biological acanthocephalan species of the Echinorhynchus gadi Zoega in Müller, 1776 complex and differentiate between dorsal and ventral hook rows from the proboscis of E. salmonis Müller, 1784. Proboscis profiler is free software and can be downloaded from . 相似文献
This study reports the length–weight relationships (LWRs) for two elasmobranch species, Rhinobatos horkelii Müller & Henle, 1841 and Zapteryx brevirostris (Müller & Henle, 1841) collected from the southwestern Atlantic, off Brazil. Both are considered endangered species. The LWR data can be taken into consideration for further management and conservation plans. 相似文献
Reduced expression of a ~150 kDa protein was unexpectedly observed while investigating Norrin protein in a transgenic murine model in which Müller cells can be selectively and inducibly disrupted. Isolation of this unknown protein via ion exchange and hydrophobic interaction chromatography followed by Tandem mass spectrometry identified it as Inter‐photoreceptor retinoid‐binding protein (IRBP). Significantly reduced IRBP mRNA expression was observed at the early and late stages after Müller cell disruption. IRBP protein expression was also consistently reduced to 5.7% of the control level as early as 1 week after Müller cell disruption. This down‐regulation of IRBP was accompanied by focal hyperfluorescent dots and cytotoxic N‐retinylidene‐N‐retinylethanolamine (A2E) accumulation. In vitro treatment of cone photoreceptor cell lines with conditioned medium collected from stressed Müller cells suggested that Müller cells regulated photoreceptors expression of IRBP via secreted factor(s). In vivo studies suggested that one of these secreted factors was tumour necrosis factor alpha (TNFα). These findings suggest that dysregulation of IRBP expression caused by Müller cell dysfunction may be an important early event in photoreceptor degeneration in some retinal diseases.
Supravital study of rhodamine-stained mitochondria in cells of aerial and submerged micelium of 31 strains from 9 species
from genus Agaricus (A. arvensis Schaeff., A. bisporus (Lange) Imbach, A. bitorquis (Quel.) Sacc., A. campestris L., A. excellens, (F.H. Müller) F.H. Müller, A. macrocarpus (F.H. Müller) F.H. Müller, A. silvaticus Schaeff., A. silvicola (Vittad.) Peck, A. xanthodermus Genev) and of 2 strains from 2 species from genus Pleurotus (P. ostreatus (Jacg.) P. Kumm., P. pulmonarius (Fr.) Quel.) was carried out. Mitochondrial morphogenesis in micelial cells of species from Agaricus and Pleurotus genera has many common features in distribution of mitochondria in micelial cells both under the favorable growth conditions
and during chondriom reorganization (fission and fragmentation of mitochondria to small subunits) under unfarovable growth
conditions and during aging. During the balanced growth of mycelium of heterokaryotic strains from genera Agaricus and Pleurotus for 7–14 days on agar media as well as during cultivation of mycelium of oyster mushroom and several strains of field mushroom
in submerged culture, distribution of mitochondria by the type 1 (small granular mitochondria in the apical zone—1, long rod-like
mitochondria in the subapical zone—2 and short rod-like and granular mitochondria formed as a result of fragmentation of rod-like
mitochondria in mature mycelium cells—3) was observed. Under unfarovable growth conditions (starvation), in mycelium cells
of homokaryotic strains of champignon, during long cultivation of all strains and species from the studied genera and during
cultivation on liquid wort, for majority of champignon, distribution of mitochondria by the type 2 was observed (sphere-like
mitochondria in all cells of the studied mycelium zones). Mitochondrial profiles at ultrastructural level had specific features,
such as associations of the outer mitochondrial membrane with cytoplasmic ribosomes and changes in cristae structure. The
preliminary test for apoptosis-like phenotype of the submerged mycelium cells of Bs94 champignon that hardly grows in the
submerged culture gave positive result. Thus, mitochondrial morphogenesis in mycelium cells of Agaricus and Pleurotus species under different conditions and terms of cultivation occurs similarly and is determined by a complex of physiological
and biochemical processes reflecting the state of mycelium cells. 相似文献
During the summer of 2008 and 2009, massive algal blooms repeatedly broke out in the Yellow Sea of China. These were undoubtedly
caused by the accumulations of one or more species in the macroalgal genus Ulva. In previous reports, morphological observation indicated that the species involved in this phenomenon is Ulva prolifera but molecular analyses indicated that the species belongs to an Ulva linza–procera–prolifera (LPP) clade. Correct identification of the bloom species is required to understand and manage the blooms, but the taxonomic
status of the bloom species remains unclear. In the current study, the taxonomic status of 22 selected specimens from the
Yellow Sea was assessed by using both morphological and molecular (ITS and rbcL sequences) data. In addition, 5S rDNA analyses
were performed for those samples clustering in the LPP clade, and phylogenetic tree and ribotype analyses were constructed
for determining the possible origin of the bloom. Three free-floating and two attached Ulva species were distinguished and described: Ulva compressa Linnaeus and Ulva pertusa Kjellman were found in free-floating samples; U. linza Linnaeus was found on rocks; and U. prolifera O.F. Müller was found in both habitats. Diversity in free-floating Ulva of the Yellow Sea appears to be greater than previously thought. The dominant free-floating Ulva species, U. prolifera, was not closely related to local populations attached to rocks but was closely related to populations from Japan. 相似文献
The morphology and phylogeny of two metopid ciliates, collected from anaerobic habitats in China, were investigated using live observation, protargol staining method, and SSU rDNA sequencing. The new species Metopus paravestitus nov. spec. can be distinguished by a combination of the following features: oblong cell with densely arranged ectobiotic prokaryotes perpendicular to cell surface, filiform intracytoplasmic structures packed in the anterior portion of the cell. Our work also demonstrates the wide geographical distribution of Metopus es (Müller, 1776) Lauterborn, 1916. The order Metopida is consistently depicted as a paraphylum in SSU rDNA phylogeny. Metopus paravestitus nov. spec. is closely related to its marine congeners than to freshwater forms. The present study confirms once again the non-monophyly of the genus Metopus and genus Metopidae. 相似文献
The green macroalgal genus Ulva (Ulvales, Ulvophyceae, Chlorophyta) is distributed worldwide from marine to freshwater environments. Comparative analyses of hyposalinity tolerance among marine, brackish, and freshwater Ulva species were performed by fluorescein diacetate viability counts. The subtidal marine species Ulva sp., collected from a depth of 30 m, showed the poorest tolerance to low salinity. This species died in 5 practical salinity units (PSU) artificial seawater or freshwater within 1 day. Its closely related species U. linza L. (an intertidal species) and U. prolifera Müller (a brackish species) showed varying tolerances to low salinity. After 7 days of freshwater exposure, the viability of U. linza L. decreased to approximately 20%, while U. prolifera Müller showed nearly 100% viability. The freshwater species U. limnetica Ichihara et Shimada, not yet found in coastal areas, was highly viable in seawater. 相似文献
Simulation modeling was performed to study the impact of individual variability on the population dynamics of particular cladoceran populations and the outcome of interspecific competition at low and high temperatures. The study was performed on one species of small size (Ceriodaphnia quadrangula O.F. Müller) and one species of large size (Simocephalus vetulus O.F. Müller). Laboratory experiments were performed to estimate the average values of principal demographic parameters of these species and their coefficients of variability at two temperatures, 18 and 27°C. Population dynamics of the two species in mono- and mixed cultures was simulated with and without accounting for individual variability using available published data and our own data on demographic parameters. Individual variability was shown to help populations survive unfavorable trophic conditions and to give competitive advantage over populations in which all individuals of the same age are identical. Individual variability decreased with rising temperatures due to probable acceleration of physiological processes. 相似文献
The freshwater invertebrate fauna (excluding the Protozoa) of Macquarie Island is collated. This includes two Platyhelminthes,
two Gastrotricha, three Tardigrada, 41 rotifera, at least eight Nematoda, nine Annelida, and 21 Arthropoda. The latter comprises
six species of Anomopoda, two Copepoda, two Ostracoda, an Isopoda, five Acarina, and at least five species of Insecta with
aquatic or semi-aquatic larvae. The freshwater Anomopoda (Cladocera) of Macquarie Island are re-evaluated, six species are
now recognized and the largest, identified as Daphnia gelida (Brady), is redescribed. The records of both Alona weinecki Studer and Pleuroxus macquariensis Frey are confirmed, while that of Macrothrix hirsuticornis Norman and Brady is accepted with some reservations. Alona quadrangularis (O.F. Müller) is re-instated and records of Chydorus sphaericus O.F. Müller ascribed to C. patagonicus Ekman. 相似文献
Streptomyces coelicolor Müller contains two types of superoxide dismutase (SOD) containing Ni (encoded by sodN) or Fe (encoded by sodF). Unlike a single species of Fe-containing SOD in Müller strain, multiple forms of FeSODs were detected in S. coelicolor A3(2) strain by activity staining and Western blot analysis. Genomic Southern hybridization suggested the presence of at least two copies of the sodF-like gene in A3(2). Two different genes for FeSOD (sodF1 and sodF2) were isolated from the phage library of A3(2) genome. The nucleotide sequence of the sodF1 coding region was identical with the unique sodF gene from Müller while that of sodF2 shared 88% identity. The gene products of sodF1 and sodF2 were identified by activity staining and immunoblot analysis. Expression from the sodF1 gene was repressed by nickel as sensitively as Müller sodF, suggesting the presence of Ni-responsive regulatory site within the region shared by the two genes. Among 12 other Streptomyces species examined, only S. fradiae contained two FeSOD-like polypeptides. We postulate that the additional copy of the sodF gene (sodF2) was provided by the horizontal transfer from remotely related bacteria. 相似文献
Until recently, Histoplasma capsulatum was believed to harbour three varieties, var. capsulatum (chiefly a New World human pathogen), var. duboisii (an African human pathogen) and var. farciminosum (an Old World horse pathogen), which varied in clinical manifestations and geographical distribution. We analysed the phylogenetic relationships of 137 individuals representing the three varieties from six continents using DNA sequence variation in four independent protein‐coding genes. At least eight clades were idengified: (i) North American class 1 clade; (ii) North American class 2 clade; (iii) Latin American group A clade; (iv) Latin American group B clade; (v) Australian clade; (vi) Netherlands (Indonesian?) clade; (vii) Eurasian clade and (viii) African clade. Seven of eight clades represented genetically isolated groups that may be recognized as phylogenetic species. The sole exception was the Eurasian clade which originated from within the Latin American group A clade. The phylogenetic relationships among the clades made a star phylogeny. Histoplasma capsulatum var. capsulatum individuals were found in all eight clades. The African clade included all of the H. capsulatum var. duboisii individuals as well as individuals of the other two varieties. The 13 individuals of var. farciminosum were distributed among three phylogenetic species. These findings suggest that the three varieties of Histoplasma are phylogenetically meaningless. Instead we have to recognize the existence of genetically distinct geographical populations or phylogenetic species. Combining DNA substitution rates of protein‐coding genes with the phylogeny suggests that the radiation of Histoplasma started between 3 and 13 million years ago in Latin America. 相似文献
Eudiaptomus anatolicus n.sp. displays similarity to E. transylvanicus (Daday, 1890) by possessing an outer marginal spine
located proximally on the second exopodite segment of the male right P5, but it differs from this closest species in the presence of a chitinous projection on the second exopodite segment of the
male right P5, and in the typical shape of the female's thoracic wings. E. transylvanicus (Daday, 1890) has three chitinous processes located
on the basipodite segment of the male right P5, whereas Eudiaptomus anatolicus n.sp. has only one small process on this part.
This new species is living in lake Poyraz, which is small and shallow. Some cladoceran species, namely, Pleuroxus truncatus
(O.F. Müller, 1785), Pleuroxus laevis (Sars, 1862), Pleuroxus trigonellus (O.F. Müller, 1785), Simocephalus exspinosus (Koch,
1841), Eurycercus lamellatus (O.F. Müller, 1785), Alonella excisa (Fischer, 1854), Lathonura rectirostris (O.F. Müller, 1785),
Pseudochydorus globosus (Baird, 1843) and two cyclopoid copepods, Megacyclops viridis (Jurine, 1820) and Eucyclops serrulatus
(Fischer, 1851) share the same habitat.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
We determined the mechanisms of glutamate and ATP release from murine retinal glial (Müller) cells by pharmacological manipulation
of the vascular endothelial growth factor (VEGF)- and glutamate-induced inhibition of cellular swelling under hypoosmotic
conditions. It has been shown that exogenous glutamate inhibits hypoosmotic swelling of rat Müller cells via the induction
of the release of ATP (Uckermann et al. in J Neurosci Res 83:538–550, 53). VEGF was shown to inhibit hypoosmotic swelling of rat Müller cells by inducing the release of glutamate (Wurm et al. in
J Neurochem 104:386–399, 55). The swelling-inhibitory effect of VEGF in murine Müller cells was blocked by an inhibitor of vesicular exocytosis, by a
modulator of the allosteric site of vesicular glutamate transporters, and by inhibitors of phospholipase C and protein kinase
C. The swelling-inhibitory effect of glutamate in murine Müller cells was prevented by inhibitors of connexin hemichannels.
The effects of both VEGF and glutamate were blocked by tetrodotoxin and by an inhibitor of T-type voltage-gated calcium channels.
Murine Müller cells display connexin-43 immunoreactivity. The data suggest that Müller cells of the murine retina may release
glutamate by vesicular exocytosis, whereas ATP is released through connexin hemichannels. 相似文献
We analysed ontogenetic shape change in the planorbid limpet Ancylus fluviatilis (Müller, 1774) in two rivers in Southern Italy. We developed a new method to discriminate among different cohorts in Ancylus, based on principal component analysis. The method is useful when shape change during growth is allometric, as in our study model. We discovered that bivoltinism occurs in Ancylus in Southern Italy, contrary to previous accounts, which invariably describe A. fluviatilis as a semelparous and univoltine species, although acknowledging difficulty in discriminating among cohorts. The methods presented here may potentially help research in reproductive traits in many other mollusc populations where shape change during ontogeny is demonstrated to be allometric. 相似文献
Extracellular nucleotides mediate glia-to-neuron signalling in the retina and are implicated in the volume regulation of retinal
glial (Müller) cells under osmotic stress conditions. We investigated the expression and functional role of ectonucleotidases
in Müller cells of the rodent retina by cell-swelling experiments, calcium imaging, and immuno- and enzyme histochemistry.
The swelling of Müller cells under hypoosmotic stress was inhibited by activation of an autocrine purinergic signalling cascade.
This cascade is initiated by exogenous glutamate and involves the consecutive activation of P2Y1 and adenosine A1 receptors, the action of ectoadenosine 5′-triphosphate (ATP)ases, and a nucleoside-transporter-mediated
release of adenosine. Inhibition of ectoapyrases increased the ATP-evoked calcium responses in Müller cell endfeet. Müller
cells were immunoreactive for nucleoside triphosphate diphosphohydrolases (NTPDase)2 (but not NTPDase1), ecto-5′-nucleotidase,
P2Y1, and A1 receptors. Enzyme histochemistry revealed that ATP but not adenosine 5′-diphosphate (ADP) is extracellularly metabolised
in retinal slices of NTPDase1 knockout mice. NTPDase1 activity and protein is restricted to blood vessels, whereas activity
of alkaline phosphatase is essentially absent at physiological pH. The data suggest that NTPDase2 is the major ATP-degrading
ectonucleotidase of the retinal parenchyma. NTPDase2 expressed by Müller cells can be implicated in the regulation of purinergic
calcium responses and cellular volume. 相似文献