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1.
Satellite DNAs (satDNAs) and transposable elements (TEs) are among the main components of constitutive heterochromatin (c-heterochromatin) and are related to their functionality, dynamics, and evolution. A peculiar case regarding the quantity and distribution of c-heterochromatin is observed in the genus of bees, Melipona, with species having a low amount of heterochromatin and species with high amount occupying almost all chromosomes. By combining low-pass genome sequencing and chromosomal analysis, we characterized the satDNAs and TEs of Melipona quadrifasciata (low c-heterochromatin) and Melipona scutellaris (high low c-heterochromatin) to understand c-heterochromatin composition and evolution. We identified 15 satDNA families and 20 TEs for both species. Significant variations in the repeat landscapes were observed between the species. In M. quadrifasciata, the repetitive fraction corresponded to only 3.78% of the genome library studied, whereas in M. scutellaris, it represented 54.95%. Massive quantitative and qualitative changes contributed to the differential amplification of c-heterochromatin, mainly due to the amplification of exclusive repetitions in M. scutellaris, as the satDNA MscuSat01-195 and the TE LTR/Gypsy_1 that represent 38.20 and 14.4% of its genome, respectively. The amplification of these two repeats is evident at the chromosomal level, with observation of their occurrence on most c-heterochromatin. Moreover, we detected repeats shared between species, revealing that they experienced mainly quantitative variations and varied in the organization on chromosomes and evolutionary patterns. Together, our data allow the discussion of patterns of evolution of repetitive DNAs and c-heterochromatin that occurred in a short period of time, after separation of the Michmelia and Melipona subgenera. 相似文献
2.
Summary In most Hymenoptera species the queen mates once but in a small number of species, multiple matings can occur normally. So, in this study, physogastric M. quadrifasciata queens were mated with a second male to investigate how these queens, naturally inseminated and laying eggs, use spermatozoa stored in their spermatheca, when they are mated with a second male. Results demonstrate that spermatozoa of different males mix in the spermatheca of M. quadrifasciata queens and that there is a gradual increase in the utilisation of spermatozoa of the second male, which could be explained by a competition among spermatozoa of different drones over the way in which spermatozoa are stored in the spermatheca. 相似文献
3.
Summary In central Portugal, 28 species of ants were found in oak, 25 in pine, 35 in eucalyptus and 12 in arable habitats, a total of 43 species. They include five numerically dominant species, the exotic Argentine ant. Linepithema (Iridomyrmex) humile and four native species, Crematogaster scutellaris, Pheidole pallidula, Tapinoma nigerrimum and Tetramorium hispanicum.
L. humile occurred in 34% of sampled sites. When present, it was abundant in all three arboreal habitats, where it was associated with strikingly decreased ant species richness and equitability. Such diversity was greater in L. humile-colonised arable habitats, where the ant was much less abundant than in the arboreal habitats.Where L. humile was absent, C. scutellaris and P. pallidula were usually co-dominants in oak and pine, and T. nigerrimum and T. hispanicum in the arable habitat, but all were absent or rare in eucalyptus. Ants were numerically least abundant in eucalyptus but, in the absence of L. humile, species richness was greater and the community more equitable than in the other habitats. L. humile-absent arable habitats supported the poorest and least equitable ant community. 相似文献
4.
Karyotype and external morphological analyses were conducted on Medicago ciliaris, M. intertexta, M. muricoleptis and M. granadensis which comprise the Intertextae section of the genus Medicago. All species were found to have 2n = 16 chromosomes (= 2 ×), including one pair of satellite chromosomes in each respective complement. Karyotypic evolution in the Intertextae involves changes in absolute chromosome size and in centromeric and relative size symmetry. Numerical taxonomic analyses were conducted independently on 17 karyotypic features and on 16 features of external morphology. The results of the two sets of analyses proved comparable, with M. ciliaris and M. intertexta forming a fairly close pair, and the remaining two species appearing to have more distant relationships to each other and to the first pair. These observations are consistent with the infertility relationships and chorologies of the species. It is suggested that M. muricoleptis and M. granadensis are derived from the M. ciliaris/intertexta species complex with M. granadensis arising from M. muricoleptis, or these two species independently evolving from a common species complex. Chromosomal and numerical analyses suggest that M. ciliaris is the most primitive and M. granadensis the most derived species of the Intertextae. 相似文献
5.
Significant relationships between the emergence of adult predatory species, Ophyra aenescens (Wiedemann) and Muscina stabulans (Fallen) and prey, Musca domestica L., Fannia femoralis (Stein) and F. canicularis (L.) existed on 10 poultry ranches in southern California. Predatory species may function in natural control at intervals
throughout the year, especially on predominant prey, F. femoralis and F. canicularis. Dipterous species, especially O. aenescens and F. femoralis, were only moderately influenced by the surface area of breeding habitat available. Accuracy in the measurement of population
trends in Diptere may be enhanced by increasing the number of samples at any given ranch rather than the addition of study
ranches. Parasitism, ranging from 22.6–37.8% of collected puparia, involved principally 3 species, Muscidifurax zaraptor Kogan & Legner, M. raptor Girault & Sanders and Spalangia cameroni Perkins.
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6.
The present study focusses on allozyme variation in the commensal house mouse Mus musculus, the pygmy field mice M. booduga and M. terricolor, and the spiny mouse M. platythrix. Genetic heterozygosity was estimated using a set of 24 polymorphic biochemical genetic markers. The extent of variability
present in M. booduga, M. terricolor and M. platythrix has been compared with that in the M. musculus complex. Levels of allozyme variation at species level indicate that M. musculus has the maximum heterogeneity, followed by M. booduga and M. terricolor, while M. platythrix shows comparatively homogeneous genetic make-up. Gene frequency data have been used to trace phylogenetic relationships among
these four species. 相似文献
7.
Based on collectors' measurements of 1,040 specimens, variation of relative tail length [RTL = (tail length/head and body
length) × 100] has been studied in Macaca fascicularis and M. mulatta, two closely related species that replace one another in tropical Asia and subtropical Asia, respectively. RTL usually is
greater than 90 in M. fascicularis and usually is less than 60 in M. mulatta; intermediate values occur in only 3.5% of specimens studied. Within each species, RTL is approximately equal in females
and males. From infancy to adulthood, RTL tends to decline in both species. In M. fascicularis, RTL generally decreases with increasing latitude; in M. mulatta, RTL is approximately constant latitudinally. Where the geographic ranges of these two species meet at ca. 15°N in the Indochinese
Peninsula, a few specimens have been collected in which RTL and dorsal pelage color are intermediate between those in M. fascicularis and M. mulatta. The observed pattern of variation suggests that the ranges of M. fascicularis and M. mulatta formerly were separated by a zoogeographic barrier — perhaps during a Pleistocene glacial interval. After disappearance of
the postulated barrier, the ranges of these two species apparently became contiguous and limited hybridization has occurred. 相似文献
9.
Medicago intertexta and M. ciliaris have been controversially recognized as separate species. The only reliable diagnostic character, gland-tipped trichomes on the fruits in M. ciliaris, is controlled by presence of a single dominant allele, and such one-character taxonomies are debatable. Contributing to the difficulty, M. muricoleptis and M. granadensis, the other two species of Medicago section Spirocarpos subsection Intertextae, are sometimes confusingly similar to M. intertexta or to each other. Allozyme differences provided 95% verification of the suitability of the gland-tipped trichome character for separating M. intertexta and M. ciliaris, thus corroborating their recognition as separate taxa. Several measures of allozyme variation indicated that M. intertexta is more polymorphic than its sister species. Heterozygosity was also highest in M. intertexta, suggestive of a higher outcrossing rate, which is also consistent with larger floral size. Heterozygosity of M. intertexta was concentrated in Sicily and nearby countries. Taxonomic difficulties in identifying Sicilian M. intertexta are well known, and may be the result of interspecific hybridization and introgression. Medicago muricoleptis differed from the above two species in the frequency of several alleles, while M. granadensis possessed numerous unique alleles consistent with its complete absence of genetic exchange with the other three substantially interfertile species. 相似文献
10.
Three species of Marasmius from Japan are described and illustrated here for the first time: M. glabellus, M. pallidocephalus and M. wettsteinii. The specimens were collected in Hokkaido. 相似文献
11.
Macaca nemestrina and M. fascicularis coexist through much of their geographic ranges in Southeast Asia, but locally they segregate into drier hilly terrain and
wetter alluvial riverine terrain respectively. Since M. fascicularis travel arboraally and M. nemestrina, travel terrestrially, structural characteristics of habitats on the two different substrates may explain local segregation
of these two species. This paper reports measures comparing habitat structure of M. fascicularis fascicularis and M. nemestrina nemestrina at the Mentoko site in East Kalimantan, Indonesia. Results show that (1) ground cover is thicker; (2) there are fewer gaps
in the canopy; and (3) the foliage of the canopy is more dense in habitat occupied by arboreal M. f. fascicularis than in habitat occupied by M. n. nemestrina. These differences in habitat structure appear to explain segregation of the two species at the Mentoko. Similar differences
in habitat may permit coexistence of the two species throughout their geographical ranges. 相似文献
12.
The biology and host specificity of the seed-feeding bruchids, Acanthoscelides quadridentatus (Schaeffer) and A. puniceus Johnson, from Mexico were studied in quarantine facilities in Australia. Distinguishing characters in the genitalia of each
species are illustrated. Oviposition was recorded on 16 of 73 species of plants tested but larvae died without entering pods
or seeds, except on Mimosa invisa K. F. P. von Martius and M. pigra L. Larvae entering seeds of M. invisa died in the first instar. The bruchids were clearly specific to M. pigra and were subsequently released as part of a program for biological control of this weed in the Northern Territory, Australia
in April 1983 and thailand in July 1984.
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13.
Two new species of the coelomycete genus Xenidiocercus are described and illustrated, X. macrospora on leaves of Macaranga rowlandii and X. pyriformis on leaves of M. huraefolia. They differ from the type species in having wider and ellipsoidal or pyriform conidia. A key to species of Xenidiocercus and Idiocercus is provided. 相似文献
14.
Thirty-eight strains of 12 Microsporum and 10 Arthroderma (Nannizzia) species were investigated by analysis of mitochondrial DNA with 6 restriction enzymes, and classified into 13 genetic groups. The phylogenetic tree of the 13 groups thus established was constructed. On the tree, M. audouinii, M. langeronii, M. rivalieri, M. distortum, M. equinum, M. ferrugineum and A. otae comprise one genetic group and are suggested to be the same species. A. gypseum, A. fulvum, M. duboisii, M. ripariae, A. incurvatum, A. persicolor and A. obtusum are clustered on one of five boughs of the tree indicating their close relation. A. racemosum and A. cajetani are also closely related. 相似文献
15.
Summary. Internal transcribed spacer 1 (ITS-1) sequences of the nuclear rDNA of eight bee species of the genus Melipona were studied. Complete ITS-1 sequence and flanking regions from three Melipona species were PCR-amplified, cloned, sequenced, and their variability compared. These sequences show length variation (1391 to 1417 bp), several repeated elements of one, two, three, and four nucleotides, and a repeated tandem sequence of approximately 80 bp. The low variation level between M. quadrifasciata and M. mandacaia sequences supports the hypothesis that they diverged recently. PCR-amplification, cloning, and sequencing of a partial ITS-1 sequence (394 to 496 bp) of eight Melipona species and two outgroups were performed and the obtained sequences used for phylogenetic analysis. The single tree estimated from parsimony analysis recovered four well-defined clades and monophyly of the genus Melipona. The phylogenetic relationships derived from sequences of ITS-1 fragments corroborate the taxonomic classification of Melipona based on morphological characters.Received 17 July 2003; revised 10 May 2004; accepted 1 June 2004. 相似文献
16.
The dermatophytic fungi Trichophyton spp and Microsporum spp secrete ferrichrome type siderophores under low iron conditions. Three different species of Microsporum, i.e. M. qypseum, M. canis and M. audouinii, as well as T. rubrum produce ferrichrome C and ferricrocin, whereas T. mentagrophytes and T. tonsurans produce only ferrichrome. The identification of the siderophores was established by means of thin layer chromatography, high performance liquid chromatography and mass spectroscopy. 相似文献
17.
Thirteen species of Characeae were analyzed for their free amino acid contents. Large amounts of isoasparagine, accounting
for 10 to 50% of the total free amino acids, were found in extracts from Chara (5 species including one unidentified), Nitellopsis (1 species), and Lamprothamnium (1 species). In contrast, no isoasparagine was detected in Nitella (5 species) and Tolypella (1 species), except for N. flexilis in which as much as 40% of the free amino acids was isoasparagine. Other major amino acids found in the tested materials
were Ala, Asp, Glu and Gln. 相似文献
18.
Twenty-five samples of maize kernels collected at harvest time from geographically different corn fields in Peru, were examined for the occurrence of toxigenic Fusarium species. The most frequently recovered species were F. subglutinans (48%), F. moniliforme (46%), and F. equiseti (5%). Other Fusarium species isolated (up to 1%) included F. graminearum, F. acuminatum, F. solani, F. oxysporum, and F. culmorum. Assays of Fusarium culture extracts using Artemia salina larvae, showed F. subglutinans as one of the most toxigenic species, and its toxicity was mostly correlated to the capability to produce beauvericin (BEA). All eight tested isolates of F. subglutinans grown on autoclaved corn kernels produced BEA (from 50 to 250 mg/Kg) as well as moniliformin (M) (from 70 to 270 mg/Kg). This is the first report on BEA and M production by maize isolates of F. subglutinans from South America. 相似文献
19.
Seventy populations of North American annual Microseris, Stebbinsoseris, and Uropappus species were examined for chloroplast and nuclear ribosomal DNA restriction site variability to determine the origin of the allotetraploid species S. heterocarpa and S. decipiens. Previously identified chloroplast DNA restriction site variants were used in concert with restriction site variation for Nco I in the nuclear-encoded ribosomal DNA repeat. The presence of two, mutually exclusive restriction site gains were observed in diploid populations of M. douglasii; these same variants were also found in populations of allotetraploid S. heterocarpa, indicating mutiple origins of this species from different maternal diploid populations of M. douglasii. Variation in the rDNA repeat between the diploid annual species and the putative paternal genome of U. lindleyi was found to be additive in S. heterocarpa. A similar relationship was observed for the origin of S. decipiens; cpDNA restriction site variants found in M. bigelovii and M. douglasii were present in S. decipiens. The rDNA Nco I variants also were additive in this purported allotetraploid. These results confirm the reticulate evolutionary pattern in Stebbinsoseris and provide another example of multiple origins of intergeneric allopolyploids. 相似文献
20.
One hundred and four Malassezia strains (52 isolated from humans and 52 from animals) were compared using large subunit (LSU) ribosomal RNA sequence similarity and nuclear DNA complementarity. Eight groups of strains were recognized as genetically distinct species. Each taxon was confirmed by a homogeneous mole % GC and percentages of DNA/DNA reassociations higher than 85%. The non-lipid-dependent Malassezia yeasts were maintained as the unique taxon M. pachydermatis. In contrast, lipid-dependent strains were shown to be distributed among seven species: M. furfur, M. sympodialis and M. species 1–5. These taxa matched remarkably well with morphological and serological differences documented by previous investigators. The LSU rRNA sequences allowed a further intraspecific resolution with most of genomic taxa represented by several closely related sequences: M. pachydermatis counted up to seven sequences, M. furfur four sequences, M. species 1 comprised three sequences and M. species 2 and M. species 5 two sequences. Three species, M. sympodialis, M. species 3 and M. species 4, displayed a unique type of sequence. Thus, the present report demonstrates the usefulness of sequencing for both taxonomic and epidemiological purposes. 相似文献
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