共查询到20条相似文献,搜索用时 15 毫秒
1.
I. N. Ryazanova 《Russian Journal of Marine Biology》2007,33(4):267-270
The karyotype of the sculpin Myoxocephalus jaok from the Ussuriisky, Amursky, and Vostok Bays was studied. It was found that 2n = 24, among the chromosomes there were 16 metacentric, 4 submetacentric, and 4 acrocentric, NF = 44. There was no variation in the number of chromosomes, and no differences between male and female karyotypes were revealed. A comparison of Myoxocephalus jaok, M. brandti and M. stelleri karyotypes was performed. The pronounced distinction of Myoxocephalus jaok karyotype resulting from chromosomal rearrangements was shown. 相似文献
2.
The morphometric characteristic is composed and special traits of the biology of seven populations of the Siberian sculpin Cottus sibiricus from three large river basins of Siberia are considered (the Lena, Yenisei, and Ob basins). The studied populations demonstrate a rather wide range of variation of biological characteristics and exterior characters. The fish from different water bodies differ in longevity, growth rate, term of maturation, and, as a consequence, in definite size. However, there is no geographic regularity in this variation. Morphometric investigations also demonstrated the absence of clear geographic variation at a relatively high intrapopulational polymorphism. With consideration of the obtained data, it may be concluded that in spite of internal heterogeneity there are no reasons for subdivision of the Siberian sculpin into geographic forms (subspecies). 相似文献
3.
V. V. Zemnukhov 《Russian Journal of Marine Biology》2018,44(1):84-86
Sexual dimorphism in the stone cockscomb Alectrias alectrolophus was studied for the first time. No pronounced differences were found in plastic characters between the females and males of this species; however, there were differences in the structure of the urogenital papilla that allow reliable sex determination. 相似文献
4.
Polar bears, Ursus maritimus, throughout their range, are nutritionally dependent on ringed (Phoca hispida) and bearded seals (Erignathus barbatus), which are predominantly caught on the sea ice. Other marine prey species are caught and consumed, but less frequently.
As the annual sea ice retreats, polar bears throughout their range are forced ashore, where they mostly live off their stored
adipose tissue. However, while land-bound they have been observed catching birds and terrestrial mammals. Although polar bears
evolved from brown bears (U. arctos), direct observations of polar bears diving for and catching fish have not been reported. Here, we document observations
of a young male polar bear catching Arctic charr (Salvelinus alpinus) and Fourhorn sculpin (Myoxocephalus
quadricornis) by diving in Creswell Bay, Nunavut. We recorded six search bouts, where six fish were caught during dives, which were preceded
by a snorkel. The average dive and snorkel length was (mean ± SD) 13 ± 5 and 6 ± 2 s, respectively. 相似文献
5.
D. J. Goyder 《Kew Bulletin》2008,63(2):331-333
Summary
Funastrum rupicola Goyder, a new species of Apocynaceae: Asclepiadoideae from Bolivia, is described and illustrated. The conservation status of this species is assessed. 相似文献
6.
Two repeated DNA sequences isolated from a partial genomic DNA library of Helianthus annuus, p HaS13 and p HaS211, were shown to represent portions of the int gene of a Ty3 /gypsy retroelement and of the RNase-Hgene of a Ty1 /copia retroelement, respectively. Southern blotting patterns obtained by hybridizing the two probes to BglII- or DraI-digested genomic DNA from different Helianthus species showed p HaS13 and p HaS211 were parts of dispersed repeats at least 8 and 7 kb in length, respectively, that were conserved in all species studied. Comparable hybridization patterns were obtained in all species with p HaS13. By contrast, the patterns obtained by hybridizing p HaS211 clearly differentiated annual species from perennials. The frequencies of p HaS13- and p HaS211-related sequences in different species were 4.3x10(4)-1.3x10(5) copies and 9.9x10(2)-8.1x10(3) copies per picogram of DNA, respectively. The frequency of p HaS13-related sequences varied widely within annual species, while no significant difference was observed among perennial species. Conversely, the frequency variation of p HaS211-related sequences was as large within annual species as within perennials. Sequences of both families were found to be dispersed along the length of all chromosomes in all species studied. However, Ty3 /gypsy-like sequences were localized preferentially at the centromeric regions, whereas Ty1/ copia-like sequences were less represented or absent around the centromeres and plentiful at the chromosome ends. These findings suggest that the two sequence families played a role in Helianthusgenome evolution and species divergence, evolved independently in the same genomic backgrounds and in annual or perennial species, and acquired different possible functions in the host genomes. 相似文献
7.
Nguyen Van Du 《Kew Bulletin》2008,63(3):491-493
Summary
Typhonium stigmatilobatum V. D. Nguyen, a new species from Vietnam, is described and illustrated. 相似文献
8.
Summary
Linaria khalkhalensis Hamdi & Assadi is described as a new species from Azerbaijan and Guilan provinces (northern Iran), belonging to Linaria sect. Linaria. It is close to Linaria lineolata Boiss. and L. elymaitica (Boiss.) Kuprian., which it resembles in habit and vegetative features. However, floral and seed characters together with
a distinctive geographical distribution, warrant recognition at the species rank. An illustration of the new species, a distribution
map, scanning electron micrographs of seed and capsule surfaces, and an identification key are also included. 相似文献
9.
Noel H. Holmgren 《Brittonia》2018,70(1):115-139
A revision of Penstemon sect. Saccanthera subsect. Serrulati includes a new species (P. salmonensis), a new variety (P. triphyllus var. infernalis), and the elevation of a subspecies to species (P. curtiflorus), bringing the total number of species to eight, which are keyed and described, complete with nomenclature and type citations. 相似文献
10.
Summary A new and probably endemic species of Cambessedesia DC. is described from campo rupestre vegetation, as part of a floristic survey of Melastomataceae from the S?o José mountain range, Tiradentes District, Minas Gerais State, Brazil.
Miscellaneous Accepted for publication April 2008. 相似文献
11.
Summary
Bulbophyllum fendlerianum is newly described based on a collection of August Fendler in Venezuela, deposited at the Royal Botanic Gardens, Kew. It
was previously confused with B. manarae, but differs significantly from the latter species in its petal and lip shape, particularly the callus. 相似文献
12.
The first official finding of the Amur sculpin Mesocottus haitej and Cottus szanaga is reported for the basin of Tugur River (Shantarsky zoogeographical region). Previously, these species were known for this region from the literature only. 相似文献
13.
14.
New combinations are proposed in anticipation of the Polygonaceae treatment in the forthcoming volume of Intermountain Flora:
Polygonum kelloggii var. esotericum, P. kelloggii var. watsonii
,
Rumex densiflorus var. pycnanthus
,
R. salicifolius var. utahensis, and R. occidentalis var. tomentellus. Typifications are proposed to facilitate ongoing studies in Polygonaceae and to maintain current usage. 相似文献
15.
A new cottid species, Microcottus matuaensis, is described on the basis of 16 specimens (27.9–81.3mm SL) collected from tide pools of Matua Island, central Kuril Archipelago. This species is the second species of the genus Microcottus, and is distinguished from M. sellaris in having three pairs of distinct bony tubercles on the dorsal surface of occiput, a deeply concave interorbital space, and absence of the first pore of the supraorbital sensory canal. 相似文献
16.
S. Yu. Neznanova 《Cell and Tissue Biology》2018,12(3):264-270
With the help of scanning and transmission electron microscopy, the morphology of spermatozoa of Icelus spiniger and egg envelopes of I. spiniger and I. spatula has been studied. Spermatozoa have an elongated head flattened on one side, an insignificant centriolar fossa, and numerous mitochondria in the middle section. The axoneme has a structure described by the formula 9 + 2. The envelopes of oocytes of both species have a follicular membrane, chorion, and zona radiata. 相似文献
17.
A genetic transformation system has been developed for callus cells of Crataegus
aronia using Agrobacterium
tumefaciens. Callus culture was established from internodal stem segments incubated on Murashige and Skoog (MS) medium supplemented with
5 mg l−1 Indole-3-butyric acid (IBA) and 0.5 mg l−1 6-benzyladenine (BA). In order to optimize the callus culture system with respect to callus growth and coloration, different
types and concentrations of plant growth regulators were tested. Results indicated that the best average fresh weight of red
colored callus was obtained on MS medium supplemented with 2 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 1.5 mg l−1 kinetin (Kin) (callus maintenance medium). Callus cells were co-cultivated with Agrobacterium harboring the binary plasmid pCAMBIA1302 carrying the mgfp5 and hygromycin phosphotransferase (hptII) genes conferring green fluorescent protein (GFP) activity and hygromycin resistance, respectively. Putative transgenic calli
were obtained 4 weeks after incubation of the co-cultivated explants onto maintenance medium supplemented with 50 mg l−1 hygromycin. Molecular analysis confirmed the integration of the transgenes in transformed callus. To our knowledge, this
is the first time to report an Agrobacterium-mediated transformation system in Crataegus
aronia. 相似文献
18.
I. S. Voroshilova V. S. Artamonova A. A. Makhrov Yu. V. Slyn’ko 《Biology Bulletin》2010,37(5):542-547
Dreissenids display a high diversity of shell morphology, and it is frequently difficult to ascribe some individuals from
mixed populations to one of the two species, Dreissena polymorpha (Pallas, 1771) or D. bugensis (Andrusov, 1897). Presumably, such individuals may be interspecific hybrids. We have analyzed species-specific allozyme loci
of the typical representatives of these two mussel species and putative interspecific hybrids. A natural interspecific hybrid
between D. polymorpha and D. bugensis was discovered for the first time by genetic methods. It has been demonstrated that D. bugensis was a maternal parent. 相似文献
19.
Recently, the prenyltransferase SirD was found to be responsible for the O-prenylation of tyrosine in the biosynthesis of sirodesmin PL in Leptosphaeria maculans. In this study, the behavior of SirD towards phenylalanine/tyrosine and tryptophan derivatives was investigated. Product
formation has been observed with 12 of 19 phenylalanine/tyrosine derivatives. It was shown that the alanine structure attached
to the benzene ring and an electron donor, e.g., OH or NH2, at its para-position are essential for the enzyme activity. Modifications were possible both at the side chain and the benzene ring.
Enzyme products from seven phenylalanine/tyrosine derivatives were isolated and characterized by MS and NMR analyses including
HSQC and HMBC and proven to be O- or N-prenylated derivatives at position C4 of the benzene rings. K
M
values of six selected derivatives were found in the range of 0.10–0.68 mM. Catalytic efficiencies (K
cat/K
M
) were determined in the range of 430–1,110 s−1·M−1 with l-tyrosine as the best substrate. In addition, 7 of 14 tested tryptophan analogs were also accepted by SirD and converted to
C7-prenylated derivatives, which was confirmed by comparison with products obtained from enzyme assays using a 7-dimethylallyltryptophan
synthase 7-DMATS from Aspergillus fumigatus. 相似文献
20.
For the first time, genetic analysis of the cytochrome b gene fragment haplotypes encoding the identical and the most common cytochrome b polypeptide (F1) in M. rutilus from eastern and Beringian maternal lineages was carried out. The F1 frequencies for the vole populations from Northern Priokhotye and the Kolyma basin were calculated. Considerable polymorphism of the cytochrome b F1 haplotypes within two major phylogroups of red-backed vole was supported by high molecular diversity indices for these clades. The proportion of genetic variation between the maternal lineages of F1 red-backed vole individuals (60.71%) was considerably higher than inter(24.44%) and intrapopulation (14.85%) components. The data obtained make it possible to advance a hypothesis on the convergence of the cytochrome b polypeptide structure upon sequence divergence of the corresponding gene. 相似文献