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1.
This study deals with the karyotype of the flathead sculpin Megalocottus platycephalus platycephalus (Pallas, 1814) (family Cottidae) from Odyan Bay of the Sea of Okhotsk. The karyotype is stable: 2n = 42 (2 metacentric, 2 submeta-subtelocentric, 30 subtelocentric, and 8 acrocentric chromosomes), NF = 44 + 2. The nucleolar organizers (NOs) were identified using Ag-banding in the telomere parts of the short arms of two large subtelocentric chromosomes. Variations in the number of nucleolar organizer chromosomes and in the number of NO-staining blocks were found. Comparison of the karyotype of M. p. platycephalus with the karyotypes of previously studied species of the genus Myoxocephalus from the Sea of Japan and the Sea of Okhotsk revealed their significant similarity in the main features and difference in the number and localization of NORs.  相似文献   

2.
The typology, number and placement of antennal sensilla of the click beetle Melanotus villosus (Geoffroy) (Coleoptera: Elateridae) were studied using scanning electron microscopy. On both the males and females the antennae are made up of the scape, pedicel and nine flagellomeres. Two types of basiconic sensilla, three types of trichoid sensilla, one type of styloconic sensilla, one type of chetoid sensilla, dome-shaped sensilla, grooved pegs, and Böhm sensilla all appear on the antennae of the beetles of both sexes, with the exception of trichoid sensilla type II, whose large number (average of 1635 hairs per antenna) was found only in male beetles. Sensilla trichodea type II evidently respond to the sex pheromone produced by the female beetle. Unlike the other two click beetles, studied up till now, Agriotes obscurus and Limonius aeruginosus, the trichoid and basiconic sensilla of M. villosus, whose proven or assumed function is olfactory, are located predominantly on the flagellomeres ventral extensions. It is assumed that the placement of the olfactory sensilla, mainly on the ventral side of M. villosuss antennae, and their more or less even distribution on the flagellomeres, can be seen as morphological adaptation of this species of insect, whose specific behavioural reaction of olfactory searching is flying, both before and after contact with an odour plume.  相似文献   

3.
A new species of dicyemid mesozoan is described from a cuttlefish Sepia latimanus Quoy and Gaimard collected off Nago, Naha and Onnason, Okinawa Islands, Ryukyu Islands, Japan. Dicyemennea ryukyuense n. sp. is a large species that reaches about 5 mm in length. The vermiform stage is characterised by 23 peripheral cells, a conical calotte and an axial cell that extends to the base of the propolar cells. The infusoriform embryo consists of 37 cells; two nuclei are present in each urn cell and the refringent bodies are solid. In the type of reproductive strategy, rhombogens of D. ryukyuense form a small number of infusorigens and produce a relatively large number of gametes per infusorigen. In the family Dicyemidae, Dicyemennea Whitman, 1883 is the largest group after Dicyema von Kölliker, 1849. Other dicyemid species, including those belonging to Dicyema, were not detected. Dicyemids have never previously been detected in cephalopods living on corals and rocks off the Ryukyu Islands, even though they are benthonic in habitat. This is the first report of a dicyemid mesozoan from S. latimanus and also from off the Ryukyu Islands. S. latimanus inhabits coral reefs, often swimming over the coral but usually lying on the sandy bottom. Dicyemids cannot possibly infect cephalopods which live exclusively over coral and rock.  相似文献   

4.
Miller JR  Wood BP  Hamilton MB 《Genetics》2008,180(2):1023-1037
A commonly used test for natural selection has been to compare population differentiation for neutral molecular loci estimated by FST and for the additive genetic component of quantitative traits estimated by QST. Past analytical and empirical studies have led to the conclusion that when averaged over replicate evolutionary histories, QST = FST under neutrality. We used analytical and simulation techniques to study the impact of stochastic fluctuation among replicate outcomes of an evolutionary process, or the evolutionary variance, of QST and FST for a neutral quantitative trait determined by n unlinked diallelic loci with additive gene action. We studied analytical models of two scenarios. In one, a pair of demes has recently been formed through subdivision of a panmictic population; in the other, a pair of demes has been evolving in allopatry for a long time. A rigorous analysis of these two models showed that in general, it is not necessarily true that mean QST = FST (across evolutionary replicates) for a neutral, additive quantitative trait. In addition, we used finite-island model simulations to show there is a strong positive correlation between QST and the difference QSTFST because the evolutionary variance of QST is much larger than that of FST. If traits with relatively large QST values are preferentially sampled for study, the difference between QST and FST will also be large and positive because of this correlation. Many recent studies have used tests of the null hypothesis QST = FST to identify diversifying or uniform selection among subpopulations for quantitative traits. Our findings suggest that the distributions of QST and FST under the null hypothesis of neutrality will depend on species-specific biology such as the number of subpopulations and the history of subpopulation divergence. In addition, the manner in which researchers select quantitative traits for study may introduce bias into the tests. As a result, researchers must be cautious before concluding that selection is occurring when QSTFST.  相似文献   

5.
We studied biotic and abiotic factors that influence pollination in two sympatric winter flowering species. Helleborus foetidus and Helleborus bocconei flower simultaneously in winter. Although climatic conditions are not favorable for biotic pollination both species rely mainly on large bees of the genus Bombus. At the beginning of flowering, harsh climatic conditions are restrictive for insect visits. As flowering continues and temperatures rise, pollinator activity increases. The two plant species share pollinators that visit them indiscriminately. The flowers of the two species differ in form and insects visit H. foetidus by inserting their heads and H. bocconei ventrally: pollen load on insects is highly specialized. With the arrival of spring, many other species start to bloom and in spite of the large number of flowers still on the plants insects abandon Helleborus species. At the end of spring increasing biotic interactions take away pollinators from the Helleborus species.  相似文献   

6.
The blue-spotted maskray, previously N. kuhlii, consists of up to eleven lineages representing separate species. Nine of these species (N. australiae, N. bobwardi, N. caeruleopunctata, N. malaccensis, N. moluccensis, N. orientale, N. vali, N. varidens, N. westpapuensis) have already been formally described and two (Indian Ocean maskray and Ryukyu maskray) remain undescribed. Here, the Indian Ocean maskray is described as a new species, Neotrygon indica sp. nov. Specimens of the new species were generally characterized on their dorsal side by a moderately large number of small ocellated blue spots, a low number of medium-sized ocellated blue spots, the absence of large ocellated blue spots, a high number of dark speckles, a few dark spots, and a conspicuous occipital mark. The new species formed a distinct haplogroup in the tree built from concatenated nucleotide sequences at the CO1 and cytochrome b loci. A diagnosis based on colour patterns and nucleotide sequences at the CO1 and cytochrome b loci is proposed. The distribution of N. indica sp. nov. includes the Indian coast of the Bay of Bengal, the Indian coast of the Laccadives Sea, and Tanzania. Considerable sampling effort remains necessary for an in-depth investigation of the phylogeographic structure of the Indian Ocean maskray.  相似文献   

7.
8.
The major histocompatibility complex (MHC) class I B gene/allelic repertoire was investigated in a pedigreed population of cynomolgus macaques of mixed Indonesian/Malaysian origin. The Mafa-B alleles detected in this cohort are mostly specific for a given geographic area, and only a small number of alleles appears to be shared with other populations. This suggests the fast evolution of Mafa-B alleles due to adaptation to new environments. In contrast to humans, the B locus in Old World monkeys displays extensive copy number variation. The Mafa-B and previously defined -A gene combinations segregate in families and thus allowed the definition of extended haplotypes. In many cases it was possible to assign a particular Mafa-I allele to one of these Mafa-A/B haplotypes as well. The presence of a large number of stable haplotypes in this cohort of animals, which was pedigreed for up to eight generations, looks promising for developing discriminative MHC typing tools that are less cumbersome. Furthermore, the discovery of 53 unreported Mafa-B sequences expands the lexicon of alleles significantly, and may help in understanding the complex organisation of the macaque B region.  相似文献   

9.
10.
In this paper, a new species of Vasseuromys, V. bergasensis sp. nov., from the locality of Bergasa (Ebro Basin, Spain), is described. Bergasa contains a fauna belonging to the Late Oligocene (zone MP30), composed—among other species—of Issiodoromys pseudanaema and Rhodanomys transiens. The main diagnostic features of V. bergasensis sp. nov. are the presence of a long centrolophid (fused or not to the mesoconid) in the lower molars, a large reduction in the number and length of extra ridges in the upper and lower molars, the absence of extra ridges between metalophid and centrolophid and between centrolophid and mesolophid, and the absence of the metatrope in more than half the specimens of the upper teeth M1 and M2. V. bergasensis sp. nov. is similar in size to V. elegans and smaller than the other members of the genus. The age and simple dental pattern of the new species of Vasseuromys allow us to hypothesize about relationships within the genus.  相似文献   

11.
Calceolaria spp. is regarded both as a notorious weed and a popular ornamental garden plant and have medicinal application. Some taxa of the America distributed Calceolaria genus are toxic to insects and its effect has been associated with the presence of diterpenes, triterpenes and naphthoquinones. However, Calceolaria spp. also produces a number of flavonoids and phenylpropanoids that have been shown to possess interesting biological activities. All these aspects are considered in this review to allow an evaluation of the potential for utilization of the large biodiversity of Calceolaria available. The phytochemistry of many members of the Calceolaria genus is included.  相似文献   

12.
In the present study karyotypes and chromosomes of five species of the family Opisthorchiidae (Opisthorchis felineus (Rivolta, 1884), O. viverrini (Poirier, 1886), Metorchis xanthosomus (Creplin, 1846), M. bilis (Braun, 1893), and Clonorchis sinensis (Cobbold, 1875)) were compared. Karyotypes of O. felineus, M. xanthosomus, M. bilis and C. sinensis consist of two pairs of large meta- and submetacentrics and five pairs of small chromosomes (2n = 14). The karyotype of O. viverrini is 2n = 12, which indicates a fusion of two chromosomes of opisthorchid ancestral karyotype. Analysis of mitotic and meiotic chromosomes was performed by heterologous in situ hybridization of microdissected DNA probes obtained from chromosomes 1 and 2 of O. felineus and chromosomes 1 and 2 of M. xanthosomus. Results of chromosome staining (C- and AgNOR-banding) and FISH of telomeric probes and ribosomal DNA probe on opisthorchid chromosomes were used for chromosome comparison. Data on chromosome number in opisthorchid species were also discussed.  相似文献   

13.
Frankliniella zucchini transmits zucchini lethal chlorosis virus, causal agent of lethal chlorosis of zucchini squash. The characteristics of relationship between this virus with its vector have not been studied, one of the reasons being the lack of a method for rearing the thrips for laboratory studies. This work proposes a system for the rearing of F. zucchini on fresh virus free zucchini ‘Caserta’ fruits, offering a practical and efficient alternative for the supply of a large number of insects for later study of virus/vector relationship. In addition, to aid in the identification of this species of thrips, the immature and adult forms obtained from the colony were described.  相似文献   

14.
Aloe marlothii flowers during dry winter months (July–September) and produces large numbers of wind dispersed seeds. Fire disturbance in a population of several thousand A. marlothii plants at Suikerbosrand Nature Reserve, Gauteng, permitted a series of seed dispersal experiments to be conducted. Germination trials indicated that seedling emergence decreased with increased distance from a well defined aloe stand and burn area margin, with seeds dispersed up to 25 m. Flowering frequency and total seed production were positively correlated with plant height, with seed production estimated to range from 26,000 to 375,000 seeds/plant. Although a large number of seeds are produced by flowering plants the survival rate of seeds did not extend beyond the following flowering season.  相似文献   

15.
Effect of inhibitors on glucose transport in malaria (Plasmodium berghei) infected erythrocytes. International Journal for Parasitology16: 441–446. The effect of cytochalasin B and phloretin on transport of d-glucose and 2-deoxy-d-glucose into Plasmodium berghei-infected mouse erythrocytes was studied. Both the inhibitor-sensitive and insensitive fractions of transport in the infected erythrocytes were increased compared with normal erythrocytes. The i50 values (concentrations of inhibitor producing 50% inhibition) were similar for both infected and normal erythrocytes, indicating that the binding affinities of the carrier were not substantially changed, but the turnover number, availability, or the number of the carrier may have increased in infection. There was a large increase in the transport of l-glucose into infected erythrocytes. Neither inhibitor showed any effect on transport of l-glucose into infected or normal erythrocytes. d-Galactose and d-fructose also showed a large transport increase mostly insensitive to cytochalasin B. The specificity of the transport increase raises the possibility of the presence of a new pathway other than simple diffusion, or the carrier-mediated pathway revealed by cytochalasin B or phloretin inhibition.  相似文献   

16.
Parrotfishes (Labridae, Scarinae) comprise a large marine fish group of difficult identification, particularly during juvenile phase when the typical morphology and coloration of adults are absent. Therefore, the goal of this study was to test cytogenetic markers and DNA barcoding in the identification of bucktooth parrtotfish Sparisoma radians from the northeastern coast of Brazil. Sequencing of cytochrome c oxidase subunit I (COI) confirmed all studied samples as S. radians, and all showed high similarity (99–100%) with Caribbean populations. The karyotype of this species was divergent from most marine Perciformes, being composed of 2n = 46 chromosomes. These consisted of a large number of metacentric and submetacentric pairs with small amounts of heterochromatin and GC-rich single nucleolar organizer regions (NORs) not syntenic to 5S rDNA clusters. These are the first data about DNA barcoding in parrotfish from the Brazilian province and the first refined chromosomal analysis in Scarinae, providing useful data to a reliable genetic identification of S. radians.  相似文献   

17.
Myosin II is an interesting target for therapeutic intervention, as it is involved in a large number of motility-based diseases. (S)-Blebbistatin is a known micromolar inhibitor of this protein. A new series of (S)-blebbistatin derivatives with a modified A-ring was synthesized and the myosin II inhibitory properties were evaluated in vitro. In this way, we gained insight into the influence of structural modifications in this part of the scaffold on myosin II inhibitory potency. Our results indicate there are few possibilities for potency enhancement via ring A modification of the blebbistatin scaffold.  相似文献   

18.
The influence of peripheral connectivity on the survival and differentiation of Phe-Met-Arg-Phe-amide-like immunoreactive (FLI) neurons in the ventral ganglion (VG) of the fly Sarcophaga bullata (Diptera: Sarcophagidae) was examined. Isolated larval VG were cultured in vivo for 13 days. The ganglia had undergone metamorphosis and resembled in situ metamorphosed VG in morphology and in the number and location of FLI neurons. The 3 pairs of large thoracic FLI neurons survived and became translocated to the midventral position extending immunoreactive axons into the dorsal neuropil. The 5 pairs of small FLI neurons also appeared de novo in the abdominal ganglion. However, the dorsal neural sheath of the cultured VG was devoid of FMRFamide-like immunoreactivity that was so characteristic of adult VG, which suggests the importance of peripheral connectivity for the metamorphic modification of FLI neurons.  相似文献   

19.
The present study aimed to determine in vitro antimicrobial activities and phytochemical analysis of Harrisonia abyssinica and Vepris simplifolia which are commonly used as traditional medicine in Tanzania. Sensitivity of bacterial and fungal species against plants extracts were determined using serial microdilution method. In this method, the lowest inhibitory concentration which prevented microbial growth considered as minimum inhibitory concentration (MIC). The study also evaluated phytochemical compounds present in the leaf, stem and root barks of H. abyssinica. It was revealed that eight extracts from H. abyssinica inhibited growth of three bacteria namely Staphylococcus aureus, Enterococcus faecium and Streptococcus uberis at MIC value less than 1 mg/mL. It was further revealed that, three extracts from V. simplifolia exhibited high antibacterial and antifungal activity. The preliminary phytochemical analysis revealed presence of various phytochemicals namely alkaloids, terpenoid, flavonoid, tannin and saponin. It was concluded that presence of large number of phytochemicals in the plant extracts may be associated with pharmacological properties of H. abyssinica and V. simplifolia and therefore this study provide alternative to synthetic antimicrobial agents.  相似文献   

20.
The floral biology of Nymphaea mexicana Zuccarini has been investigated. Anthesis is diurnal with flowers opening and closing for two consecutive days. Flowers on the first day of anthesis are functionally female with the stigmatic papillae secreting a small quantity of fluid. Total dissolved solids of the stigmatic fluid range from 3 to 4%; glucose and fructose are in equal concentrations and a large number of free amino acids are present. Flowers are primarily visited by Dialictus bees, flies and beetles. These insects typically land on the wet stigmatic surface where the secretion loosens pollen from the insects' body. On the second day of anthesis, the anthers dehisce and the stigmatic fluid disappears. This latter phenomenon is associated with a loss of stigmatic receptivity. Since protogyny is complete, flowers are obligatorily entomophilous. After anthesis, the flower closes and submerges. The perianth and androecium abscise and decompose as the fruit matures. The fruit yields large trichomic seeds. The phylogenetic position of N. mexicana within the genus is discussed.  相似文献   

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