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1.
Appearance and location of 45S rDNA and 5S rDNA signals were compared in chromosomes of nine species of the aneuploid Zamia and their taxonomically and phylogenetically closely related Ceratozamia mexicana. The 45S rDNA signal was detected in the proximal region of six chromosomes in Zamia angustifolia, Z. integrifolia, Z. pumila and Z. pygmaea (all 2n=16); in the proximal region of 6–14 chromosomes in Z. furfuracea, Z. loddigesii, Z. skinneri and Z. vazquezii (all 2n=18); and on the proximal region of 20 chromosomes in Z. muricata (2n=23). The 5S rDNA signals were commonly seen near the terminal region of the short arm of two metacentric chromosomes
in the four species with 2n=16 and Z. furfuracea, Z. loddigesii and Z. vazquezii with 2n=18. Other 5S rDNA signals were seen near the terminal region of two terminal-centromeric chromosomes in Z. skinneri and near the terminal region of a metacentric and a telocentric chromosomes in Z. muricata. In contrast, those with 45S and 5S rDNA signals were exhibited in chromosomes of Ceratozamia mexicana in a different manner from those in the nine species of Zamia; the 45S rDNA signal in the terminal region of four metacentric and two submetacentric chromosomes and the 5S rDNA signal
near the proximal region of two metacentric chromosomes.
Received November 1, 1999 Accepted January 10, 2001 相似文献
2.
Susana Cardone Patricia Sawatani Pablo Rush Ana María García Lidia Poggio Gustavo Schrauf 《Polar Biology》2009,32(3):427-433
Deschampsia antarctica Desv. (Poaceae), known as Antarctic hairgrass, is the only grass species and one of the two vascular plant species native
to Antarctica and it is a valuable source for gene discovery associated with freezing-tolerance. In this work the karyotype
of D. antarctica collected near Jubany Antarctic Base was reported for the first time. This species presents a chromosome number of 2n = 2x = 26, with karyotypic formula 10m + 6sm + 8st + 2t. The nucleolar organizer region is located in the short arm in one of the submetacentric pairs forming a terminal satellite.
Aneusomaty, a phenomenon already reported in the genus, was detected during this study. The cytogenetic information, together
with the recent phylogenetic data will be useful for breeding strategies in agronomically valuable crops. 相似文献
3.
Age estimation and lead�Cradium dating of Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea
Cassandra M. Brooks Allen H. Andrews Julian R. Ashford Nakul Ramanna Christopher D. Jones Craig C. Lundstrom Gregor M. Cailliet 《Polar Biology》2011,34(3):329-338
Antarctic toothfish (Dissostichus mawsoni) are the target of an important commercial fishery in the Southern Ocean, yet age data used for management have not been
comprehensively tested for accuracy. In this study, Antarctic toothfish were aged using counts of otolith growth zones based
on criteria established for Patagonian toothfish, D. eleginoides, a closely related species. To validate these ages, the radioactive disequilibrium of lead-210 and radium-226 in otolith
cores was measured and used as an independent chronometer to accurately determine age across the range of fish caught in large
numbers by the fishery. Growth-zone counts indicated Antarctic toothfish live to at least 39 years of age, and were in close
agreement with the chronometer, validating the age estimation criteria and the accuracy of age estimates. Von Bertalanffy
growth function parameters indicated Antarctic toothfish were relatively slow-growing (k = 0.111), especially in relation to their maximum size (L
∞ = 158.9 cm). 相似文献
4.
Patagonian toothfish, Dissostichus eleginoides, collections (n = 186) from three distinct stocks (two subantarctic stocks and the stock within the Chilean ZEE) were analyzed for Hg concentration
by DMA and comparisons were made by gender, total length (TL), wet weight (WW), and population. There was no difference between
TL–WW relationships or Hg concentration by gender within any population across the range examined. The Chilean and Prince
Edward Island fish had higher TL-adjusted total Hg concentration than those from the South Georgia and may suggest a possible
human health risk. Explanation of these population differences in total Hg may be the actual sample areas and associated hydrogeographic
and oceanographic conditions. For example, sampling sites for the Chilean fish lie well outside the Antarctic Convergence
whereas the Prince Edward sites straddle the Convergence. The samples obtained from South Georgia lie well within the Antarctic
convergence, suggesting that the Polar Front may provide some type of hydrographic barrier as has been shown for this species
in terms of larval dispersal and feeding. 相似文献
5.
Ryan D. Bickel Wendy S. Schackwitz Len A. Pennacchio Sergey V. Nuzhdin Artyom Kopp 《Journal of molecular evolution》2009,69(2):194-202
Genes with overlapping expression and function may gradually diverge despite retaining some common functions. To test whether
such genes show distinct patterns of molecular evolution within species, we examined sequence variation at the bric à brac (bab) locus of Drosophila melanogaster. This locus is composed of two anciently duplicated paralogs, bab1 and bab2, which are involved in patterning the adult abdomen, legs, and ovaries. We have sequenced the 148 kb genomic region spanning
the bab1 and bab2 genes from 94 inbred lines of D. melanogaster sampled from a single location. Two non-coding regions, one in each paralog, appear to be under selection. The strongest
evidence of directional selection is found in a region of bab2 that has no known functional role. The other region is located in the bab1 paralog and is known to contain a cis-regulatory element that controls sex-specific abdominal pigmentation. The coding region of bab1 appears to be under stronger functional constraint than the bab2 coding sequences. Thus, the two paralogs are evolving under different selective regimes in the same natural population, illuminating
the different evolutionary trajectories of partially redundant duplicate genes. 相似文献
6.
Kyoko Yarita Ayako Sano Kittipan Samerpitak Katsuhiko Kamei G. Sybren de Hoog Kazuko Nishimura 《Mycopathologia》2010,170(1):21-30
Two strains resembling the neurotropic fungus Ochroconis gallopava were isolated from hot spring river water (IFM 54738 and IFM 54739). The isolates showed optimal growth at 42°C, while the
maximum growth temperature was 49°C, thus having temperature relationships similar to those of O. gallopava. Colonies were light olive green, with a color change to dark reddish brown after several passages, which was also observed
in O. gallopava. Conidia were indistinguishable from those of O. gallopava. The antifungal susceptibility profile of the isolates was also similar to that of O. gallopava, except for a lower susceptibility to micafungin. The two isolates had 100% homologous rRNA genes including the internal
transcribed spacer (ITS) region and the D1/D2 region of the large subunit. The gene fragments, as O. gallopava, could be amplified with species-specific rDNA primers, and loop-mediated isothermal amplification designed for O. gallopava yielded positive results in the two isolates. However, homologies with O. gallopava in ITS and D1/D2 regions were 79.2 and 95.9%, respectively, widely exceeding generally accepted species boundaries. These
differences were corroborated in virulence tested in experimental infection. The two isolates did not kill a mouse even until
28 days. However, mortalities of four O. gallopava strains ranged from 40 to 100%. The new isolates mainly affected the kidneys; whereas O. gallopava had a strong preference for the brain. We therefore propose a new species, Ochroconis calidifluminalis, for the two isolates. 相似文献
7.
Within the Southern Ocean, Patagonian toothfish (Dissostichus eleginoides Smitt) and southern elephant seals (Mirounga leonina Linnaeus) forage mainly on fish and cephalopods. From what is known of their diets, the proportion of fish is greatest in toothfish diet. When foraging at-sea for squid, elephant seals and toothfish most often co-occur over continental shelves and submarine plateaux surrounding sub-Antarctic land masses within the Southern Ocean. I used traditional (non-molecular) techniques to compare the squid diet of these two predators. Of the 21 squid species identified, 10 were common to the diets of both predators. One species, Gonatus antarcticus, dominated (61%) the biomass of squid consumed by toothfish, but was of little importance to the elephant seals (2.3%). By contrast, Martialia hyadesi was the most important single species to the elephant seals diet (29%), but it contributed 1% to the toothfish diet. Onychoteuthids (Kondakovia longimana, Moroteuthis ingens and Morotenthis knipovitchi) were important to both predators diets. The median sizes of five cephalopod species (Slosarczykovia circumantarctica, Galiteuthis glacialis, Gonatus antarcticus, Moroteuthis ingens and Moroteuthis knipovitchi) which were common to both the seal and toothfish diets, were significantly larger in the toothfish stomachs than in the elephant-seal stomachs. Percent similarity indices for the squids that overlapped both diets were in some cases as high as 100%. However, after between-species differences in prey size consumption were accounted for, the similarities fell to between 20 and 50%. These results indicate that the strength of the trophic interaction between the seals and the fish might be weaker than previously thought. The consumption of significantly different-sized squid can also be used to suggest spatial (vertical) foraging separation of these two predators because there is evidence for ontogenetic change in the size of squid species with depth; older, and thus larger, squids live deeper than smaller individuals of the same species. 相似文献
8.
As a step toward greater understanding of the genetics of verticillium wilt resistance in plants, we report the sequencing
of a candidate wilt resistance gene, mVe1, from the mint diploid model species, Mentha longifolia (Lamiaceae). mVe1 is a putative homolog of tomato (Solanum lycopersicum L.) verticillium wilt (Ve) resistance genes. The mVe1 gene has a coding region of 3,051 bp. The predicted mVe1 protein contains a leucine-rich repeat domain, a common feature of plant disease resistance proteins. We compared 13 mVe1 alleles from three mint species. These alleles shared 96.2–99.6% nucleotide identity. We analyzed four M. longifolia populations segregating with respect to mVe1 alleles and wilt resistance versus susceptibility and found one association between mVe1 genotype and wilt phenotype. We conclude that mVe1 may play a role in mint verticillium wilt resistance, but variation for resistance in our segregating progenies is likely
polygenic. Therefore, further investigations of mVe1 and identification of additional candidate genes are both warranted. 相似文献
9.
Results of histological analysis of gonads of female and male Antarctic toothfish Dissostichus mawsoni caught in the Ross Sea of the Pacific sector in the period of Antarctic summer (December–February) 2004–2005 are presented.
Morphological indices and index of gonad maturity are described and ecological criteria of assessment of maturity stages of
ovaries, cytological indices of oocytes, and the type of toothfish oogenesis are determined. It was established that in the
period of fishing Antarctic toothfish, females and males with gonads at maturity stage III dominate. Ovaries contain two groups
of oocytes of the period of trophoplasmatic growth and large oocytes of the nearest spawning season that comprise the smallest
proportion of total sex cells. In the testes of two male toothfish, the primary fusion of renal and generative tissues was
revealed. It is suggested that the termination of gonad maturity of toothfish takes place from March to April, and spawning
takes place from June to August. 相似文献
10.
Mario La Mesa 《Polar Biology》2007,30(10):1219-1226
Juvenile Antarctic toothfish (Dissostichus mawsoni) collected off the South Shetland Islands (CCAMLR Subarea 48.1) were aged by counting the presumed daily increments in the
sagittal otoliths. The timing and position of the first annulus was examined for each individual fish from 10 to 13 cm TL.
Under reflected light at low magnification, the otolith sections exhibited a wide opaque nucleus, with no evidence of deposition
of the first translucent zone. The average measurement of ventral and dorsal radii of these sections were, respectively, 603
and 768 μm, consistently less than the measurements done in previously estimated 1 year old fish caught in the same area.
All specimens aged in the present study were approximately 1 year old fish, with an age range between 365 and 431 days, suggesting
a significant underestimation of age in the previous studies. The value of ageing precision indices calculated was relatively
low, supporting the reliability of the reading technique applied. Two checks were easily identified in the core of all otolith
sections, interpreted tentatively as hatching and first exogenous feeding checks. Back-calculating from the time of capture,
the hatching period of D. mawsoni was estimated to occur throughout the summer season, from November to February. In conclusion, the delay in timing of deposition
of the first translucent zone, which occurs in the second winter from hatching, should be taken into account in future studies
on ageing Antarctic toothfish, as well as in the stock assessment models based on length at age data. 相似文献
11.
The architecture of the musculature of the eutardigrade species Milnesium tardigradum Doyère, 1840, Hypsibius sp. and Ramazzottius oberhaeuseri (Doyère in Ann Sci Nat Zool Sér 2(14):269–369, 1840) is investigated by phalloidin staining and confocal laser scanning microscopy. There are methodological problems in staining
eutardigrades due to physiological alterations under stress (anhydrobiosis) and due to penetration problems of the cuticle.
It is helpful to fix specimens in the state of asphyxy, where animals are stretched following an oxygen shortage in their
environment. The musculatures of all three species correspond in their general architecture, but differ in detail, such as
in the number of muscles. All muscles are isolated muscle strands. There are on each body side two dorsal and one ventral
muscle strands, in addition to a system of dorsoventral, lateral and lateroventral muscles. Seven median ventral attachment
points give rise to dorsoventral, ventrolateral and appendage muscles. The appendages receive several muscles originating
dorsally and ventrally. The number of muscles and the arrangement differ in each appendage. The fourth appendage shows the
greatest differences with a far smaller number of muscles compared to other species. The musculature shows comparably few
strict segmental patterns, for example, the musculature of each appendage differs from the other ones. By comparison with
literature data on the same species and data of Macrobiotus hufelandi it can be shown that eutardigrades have a roughly comparable muscular architecture, but that there are several differences
in detail.
Dedicated to Professor Westheide on the occasion of his 70th birthday. 相似文献
12.
The number and position of 18S–25S rDNA sites in 4 selected Lupinus species are reported for the first time. L. atlanticus, L. subcarnosus and L. paniculatus had two rDNA loci, while L. albus exhibited only one loci. Among these 4 species, all of them exhibited one large pair of strong signals that extends from
the short arm to a NOR on a chromosome satellite. L. atlanticus, L. subcarnosus, L. paniculatus had one more locus of 18–25S rDNA, but a pair of weak hybridization signals were observed in L. paniculatus when 18S–25S rDNA was used as probe. The results are discussed in terms of the evolutionary relationships among these species. 相似文献
13.
S. V. Malyshev T. V. Dolmatovich A. V. Voylokov S. P. Sosnikhina N. V. Tsvetkova A. V. Lovtsus N. A. Kartel’ 《Russian Journal of Genetics》2009,45(12):1444-1449
Studies of phenotypical expression of synaptic mutations in combination with the localization of corresponding genes on a
genetic map permit individual stages of the meiotic process to be differentiated. Two rye asynaptic genes, sy1 and sy9, were mapped with the use of microsatellite markers (SSR) in the pericentromeric regions of the long chromosome arms 7R and
2R, respectively. The sy9 gene cosegregated with two SSR markers Xscm43 and Xgwm132. The asynaptic gene sy1 was mapped within the interval between the isozyme locus Aat2 and two cosegregating loci Xrems1188 and Xrems1135 that are located at a distance of 0.4 cM proximally and 0.1 cM distally with respect to the gene lous. Possible evolutionary
relationships of the mapped genes with homeological loci of the Triticeae species and more distant cereal species, such as maize and rice, are discussed. 相似文献
14.
Based on morphological characteristics and molecular phylogeny, we reclassified Cordyceps cuboidea and allied species C. alboperitheciata, C. prolifica, and Ophiocordyceps ryogamiensis. We investigated their teleomorph-anamorph relationships and revealed that these four species have Hirsutella-like anamorphs with morphological differences between them. By analyzing their molecular phylogeny, inferred from DNA sequences
of internal transcribed spacer (ITS) and large subunit (LSU) D1/D2 region of rDNA, they were separated into four close-knit
clades. Although C. prolifica and O. ryogamiensis formed their own clades, isolates of C. cuboidea separated into two clades, i.e., a true C. cuboidea clade and one resembling a new species, the O. paracuboidea clade. The latter two species are distinguished by the fruiting region of the stroma. In addition, C. alboperitheciata is regarded as a synonym of C. cuboidea. From the morphology, teleomorph-anamorph relationships, and molecular phylogeny, we concluded these species should be assigned
to the genus Ophiocordyceps. 相似文献
15.
Phylogenetic relations within the genus Gordonia were analyzed using partial gyrB and secA1 gene sequences of 23 type species in comparison with those of 16S rRNA gene. The gyrB and secA1 phylogenies showed agreement with that constructed using 16S rRNA gene sequences. The degrees of divergence of the gyrB and secA1 genes were approximately 3.4 and 1.7 times greater, respectively, than that of 16S rRNA gene. The gyrB gene showed more discriminatory power than either the secA1 or 16S rRNA gene, facilitating clear differentiation of any two Gordonia species using gyrB gene analysis. Our data indicate that gyrB and secA1 gene sequences are useful as markers for phylogenetic study and identification at the species level of the genus Gordonia. 相似文献
16.
Brandão AD Viccini LF Salimena FR Vanzela AL Recco-Pimentel SM 《Journal of plant research》2007,120(2):317-321
The aim of this work was to determine the cytogenetic characteristics of Brazilian Lippia alba (Mill) N. E. Brown and Lantana camara Plum. that could be useful for future characterization of these genera. Our analyses revealed that Li. alba has 2n=30 chromosomes consisting of ten metacentric and five submetacentric pairs, while La. camara has 44 metacentric chromosomes. The large blocks of heterochromatin seen in both species suggest an apomorphic condition.
Six 45S rDNA sites were detected in both species by fluorescence in situ hybridization (FISH). Two and four 5S rDNA sites
were observed in Li. alba and La. camara, respectively. Meiotic analysis revealed a normal chromosomal behaviour. The number of chromosomes and the presence of 45S
rDNA and 5S rDNA sites do not exclude a possible polyploid origin. The cytogenetic differences between La. camara and Li. alba may be useful markers for differentiating these species. 相似文献
17.
Peter G. Wilson 《Kew Bulletin》2008,63(2):347-349
Summary The type specimen of Metrosideros regelii is discussed. It contains a mixture of two species, representing different genera, and a lectotype is chosen. The generic
position of the species is considered in the light of morphology and recent molecular evidence and the new combination, Mearnsia regelii, made. 相似文献
18.
Bassam Al-Safadi 《Biologia》2008,63(2):177-182
Syria is considered as one of the important centres for Daucus diversity including Daucus carota. Therefore, it is essential to study the distribution and characterization of these species in Syria. An exploration of plants
belonging to the Apiaceae family was conducted on road and field sides in several areas of Syria. Seeds (fruits) from these
plants have been also collected. The seeds were sown in pots containing peatmoss in a glasshouse and emerging plants were
grown until flowering and seed formation. The plants were classified based on leaf, umbel, and seed shape. Proteins were extracted
from the leaves and analysed using electrophoresis to establish genetic relationships among species. Seven Daucus species have been identified to grow in Syria. These are D. aureus, D. bicolor, D. carota, D. durieua, D. guttatus, D. littoralis, and D. muricatus. Isozyme and total protein analysis, cluster analysis, and correlation matrix have revealed considerable genetic variation
among studied Daucus species. Wild carrot (D. carota) came in one group with its cultivated form (D. carota ssp. sativus) and the closest species to them was D. guttatus. Species D. bicolor and D. durieua were in the same group and D. aureus and D. littoralis were in another group farther from the previous groups. The farthest species on the genetic tree was D. muricatus. 相似文献
19.
A. L. Allcock J. M. Strugnell P. Prodöhl U. Piatkowski M. Vecchione 《Polar Biology》2007,30(7):883-893
During recent cruises aboard RV Polarstern in the Antarctic Peninsula region, a new species of benthic octopodid was discovered whose generic affinities based on morphological
characteristics were uncertain. Molecular sequence analysis of six mitochondrial and nuclear genes allows this species to
be placed with confidence within the genus Pareledone. The species is described herein and morphological diagnostic characters are provided for its identification. 相似文献
20.
ITS sequences determined for 53 Erysiphe specimens on Syringa and Ligustrum collected in Europe, East Asia, and North and South America were divided into two ITS groups, S and K types. Phylogenetic
analysis showed that these two ITS types do not share a common ancestor and form separate clades. The K type on Ligustrum was identified as Erysiphe ligustri based on the three-dimensional branching pattern of appendages. Morphological observations showed that there are some morphological
differences—pigmentation of appendages and number of ascospores per ascus—between the S and K types on Syringa. Based on these morphological observations, the S and K types on Syringa were identified as E. syringae and E. syringae-japonicae, respectively. The recent abundant production of chasmothecia by lilac powdery mildew in Europe was caused by E. syringae-japonicae introduced from East Asia. DNA sequence analyses of the rDNA ITS region and the 28S rDNA, tub2, CYP51, and Chs1 genes did not support an interspecific hybrid origin for E. syringae-japonicae. Haplotype analysis suggested that E. syringae originated in North America and independently migrated to East Asia and Europe/South America. 相似文献