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1.
Infections with metacercariae of Bucephaloides gracilescens in the four-bearded rockling Enchelyopus cimbrius were studied for a year in a Norwegian fjord. The prevalence was at all times high, but abundance showed a marked decline in spring to a low level during summer. A rise in abundance, variance-to-mean ratio and frequency of smaller metacercariae in early autumn (August-September) shows infection to have occurred mainly in autumn. There were no differences in level of infection between host sexes, but a highly significant positive correlation of parasite burden with host length. No influence on the condition factor of the host was revealed, the parasite cysts in the central nervous system are believed to have low pathogenicity. A detailed account of the distribution of metacercarial cysts is given. No support for infection being via the lateral line canals is revealed, cercarial penetration is believed to be through the general surface of the head and through the unpaired fins of the trunk and tail.  相似文献   

2.
Although Codfishes are probably one of the most studied groups of all teleost fishes worldwide owing to their great importance to fisheries, their phylogeny and classification are still far from being firmly established. In this study, we present phylogenetic relationships of 19 out of 22 genera traditionally included in the Gadidae based on the analysis of entire cytochrome b and partial cytochrome oxidase I genes (1530 bp). Maximum Parsimony, Maximum Likelihood, and Bayesian analyses all recovered five main clades that correspond to traditionally recognized groupings within Gadoids. The same clades were recovered with MP analysis based on 30 morphological characters (collected from the literature). Given these findings, we propose a revised provisional classification of Gadoids: one suborder Gadoidei containing two families, the Merlucciidae (1 genus) and the Gadidae (21 genera) distributed into four subfamilies: the Gadinae (12 genera), the Lotinae (3 genera), the Gaidropsarinae (3 genera), and the Phycinae (3 genera). Lastly, nuclear inserts of mitochondrial DNA (Numts) were identified in two species, i.e., Gadiculus argenteus and Melanogrammus aeglefinus.  相似文献   

3.
A few individuals with intermediate morphology always appeared in the sympatric distributions of Gentiana straminea and G. siphonantha. These intermediate individuals were hypothesized to be the hybrids of two species after a careful evaluation of their morphological characteristics. To test this hypothesis, sequence comparison of the internal transcribed spacer (ITS) regions of the nuclear ribosomal and trnS (GCU)-trnG (UCC) intergenic spacer region of the chloroplast DNA from Gentiana straminea, G. siphonantha and the putative hybrids was performed. The results suggest that most intermediate individuals were the natural hybrids between G. straminea and G. siphonantha. In addition, we examined the sequence variation among the individuals of both parent species and analyzed the possibility leading to the incongruent identification in some individuals based on morphologic and molecular evidences, respectively. The intraspecific diversification of DNA fragments within both parent species and their high variability in hybrid swarms probably resulted from chloroplast genome recombination and incomplete lineage sorting during the early stages of speciation origin of the parent species. __________ Translated from Acta Botanica Yunnanica, 2007, 29 (1): 91–97 [译自:云南植物研究]  相似文献   

4.
Metadena phoceae n. sp. is described and figured in detail from the rectum of the shore rockling Gaidropsarus mediterraneus (Lotidae) in the Gulf of Marseilles and off Corsica. It is compared with other cryptogonimids occurring in Mediterranean and Black Sea fishes and is distinguished from its closest relatives, M. depressa (Stossich, 1883) and M. pauli (Vlassenko, 1931), which occur in sparid and sciaenid fishes, respectively, by both morphometrical and biological features. The host-specificity of cryptogonimids occurring in Mediterranean and Black Sea fishes is commented upon.  相似文献   

5.
The total polyphenol, oxygen radical absorbance capacity (ORAC), ferric reducing antioxidant power (FRAP), radical cation scavenging ability, flavonol and flavanone contents were measured in the leaves, bulbs, roots, flowers and fruit (dry weight) of two natural populations of Gethyllis multifolia (Kukumakranka) and Gethyllis villosa. The flowers and fruit of G. multifolia and G. villosa showed higher, and in some cases significantly (P < 0.05) higher antioxidant activities when compared to the leaves, bulbs and roots. This, however, was not true for the flavanone content in both species. The total polyphenol content in the fruits of G. multifolia (21.54 mg GAE/g) and G. villosa (27.64 mg GAE/g) were found to be in agreement with those of raisins (28.30 mg GAE/g), blueberries (24 mg GAE/g) and strawberries (15.40 mg GAE/g). The FRAP values of G. multifolia flowers (76.66 μmole AAE/g) and fruit (91.51 μmole AAE/g) were found to be significantly (P < 0.05) higher than those of the other plant parts (16.76 to 39.08 μmol AAE/g). On the other hand, the flowers (590.23 μmol TE/g) and fruit (741.16 μmol TE/g) of G. villosa revealed a significantly (P < 0.05) higher ORAC when compared to the other plant parts (251.25 to 410.60 μmol TE/g). A strong correlation was evident in the fruit of both species between the total polyphenols and FRAP (r = 0.95), ORAC (r = 0.95) and flavonol content (r = 0.79).  相似文献   

6.
Identification of gadoid species (Pisces, Gadidae) by PCR-RFLP analysis   总被引:3,自引:0,他引:3  
A rapid PCR-RFLP analysis was optimized to identify the presence of 3 closely related gadoid fish species: Alaska pollack Theragra chalcogramma, Pacific cod Gadus macrocephalus and Atlantic cod Gadus morhua in commercial seafood products. Gadoid universal primers were designed for PCR amplification of a 558-bp fragment encoding the mitochondrial cytochrome b gene. Without purification of the PCR products, double digestion with Eco32I and Eco105I restriction enzymes generated reproducible species-specific restriction patterns visualizing 3 fragments (106 bp, 161 bp and 291 bp) in Alaska pollack and 2 fragments (106 bp and 452 bp) in Pacific cod, whereas no cleavage was observed in Atlantic cod. This PCR-RFLP analysis is simple, rapid and reliable, and therefore can be routinely applied to discover fraudulent substitution among 3 economically important gadoid species in commercial seafood products.  相似文献   

7.
In this association mapping study, a tri-species hybrid, [Gossypium arboreum × (G. hirsutum × G. aridum)2], was crossed with MD51ne (G. hirsutum) and progeny from the cross were used to identify and map SSR markers associated with reniform nematode (Rotylenchulus reniformis) resistance. Seventy-six progeny (the 50 most resistant and 26 most susceptible) plants were genotyped with 104 markers. Twenty-five markers were associated with a resistance locus that we designated Ren ari and two markers, BNL3279_132 and BNL2662_090, mapped within 1 cM of Ren ari . Because the SSR fragments associated with resistance were found in G. aridum and the bridging line G 371, G. aridum is the likely source of this resistance. The resistance is simply inherited, possibly controlled by a single dominant gene. The markers identified in this project are a valuable resource to breeders and geneticists in the quest to produce cotton cultivars with a high level of resistance to reniform nematode.  相似文献   

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10.
The first finding of the northern rockling Ciliata septentrionalis was registered for the Eastern Murman Coast (Zelenetskaya Bay) in August 2013. The penetration of this species into the Barents Sea is linked to the favorable hydrological conditions in 2013. Zelenetskaya Bay may be considered as the easternmost margin of the geographical range of the northern rockling during the warm periods in the Barents Sea.  相似文献   

11.
Specimens of Thecaphora saponariae s. lat. from several caryophyllacean host plants belonging to the genera Cerastium, Dianthus, Petrorhagia, Saponaria, Silene, and Stellaria were studied by means of both LM, SEM, and molecular phylogenetic analyses using ITS and LSU rDNA sequences. The data show that T. saponariae s. lat. is not uniform but represents several taxa. Molecular phylogenetic analyses, correlated with morphology of the sori, spore balls, and spores, permitted the recognition of five species. Two new species, Thecaphora italica and T. cerastii are described, and two new combinations, T. alsinearum and T. melandrii are proposed. The anamorph of Thecaphora saponariae is reported for the first time. A lectotype is designated for Sorosporium silenes-inflatae. Evolutionary aspects are discussed.  相似文献   

12.

Background  

Both Gossypium hirsutum and G. barbadense probably originated from a common ancestor, but they have very different agronomic and fiber quality characters. Here we selected 17 fiber development-related genes to study their structures, tree topologies, chromosomal location and expression patterns to better understand the interspecific divergence of fiber development genes in the two cultivated tetraploid species.  相似文献   

13.
Clitopilus canariensis is described as a new species belonging to Clitopilus subgenus Rhodophana on the basis of a collection from La Palma, Canary Islands. The new species grows on humus of Cistus monspeliensis and is known from a single site. A photograph of fresh basidiomes of the type-collection and line drawings are provided.  相似文献   

14.
We describe watershed-scale habitat associations of three Cantharellus species with respect to stand age. During the 1998 autumn fruiting season we collected chanterelle sporocarps from 18 forest stands in and adjacent to the H.J. Andrews experimental forest in the central Cascade Mountains of Oregon. Sampled stands represented two age categories: old growth (350+ y) and 40–60-y-old second growth naturally regenerated from clear-cut harvest. Old growth and second growth stands were spatially paired to reduce the chance of spurious habitat relationships caused by unmeasured correlated variables. We found stand age to be a good predictor of the distribution of C. subalbidus and C. formosus, but only marginally useful for predicting the occurrence of C. cascadensis. The odds that a randomly located chanterelle sporocarp will be C. subalbidus, compared to other chanterelles, are 3–23.5 times higher in old growth than in second growth. Alternatively, there is only a 4–38 % chance that a randomly located sporocarp will be C. formosus in old growth. C. cascadensis was found to be uncommon throughout the study area and showed no significant habitat associations. The abundance of C. cascadensis increased substantially with decreasing elevation indicating that landscape features other than stand age may be more useful in predicting its occurrence.  相似文献   

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16.
Three diploid taxa – Hieracium transylvanicum (subgenus Hieracium), Hieracium caespitosum subsp. brevipilum and Hieracium pavichii (subgenus Pilosella) – from five natural Bulgarian populations were investigated embryologically. The peculiarities of the male and female gametophytes, embryo- and endospermogenesis were established in each species. The results suggest that the species propagate sexually as expected from their diploid chromosome number. However, some forms of apomixis have also been observed, e.g. somatic apospory and integumental embryony in H. pavichii. The presence of apomixis in a diploid taxon shows that polyploidy is not an obligatory prerequisite for apomixis and the two phenomena are independent. The embryological plasticity detected in H. pavichii and H. transylvanicum suggests they may have higher opportunities for adaptation and successful reproduction.  相似文献   

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Samples of males and females of G. pallidipes and G. fuscipes were collected at Lugala, Uganda, by seven different methods. There were marked differences between the infection rates of the various samples. In the case of G. pallidipes the differences in infection rate were closely associated with differences in mean age of the samples, but in the case of G. fuscipes the agreement was less close.
L'influence de la methode d'echantillonnage sur les taux d'infection a trypanosome des Glossina pallidipes et G. Fuscipes capturees
Résumé Des échantillons de Glossina pallidipes et G. fuscipes des deux sexes ont été récoltés à Lugala, Uganda, sur un buf en marche, sur un buf à l'arrêt, sur un véhicule se déplaçant lentement, dans des pièges, au repos, sur des hommes à l'arrêt, et sur des hommes en marche. Les nombres obtenus par les 7 méthodes sont indiqués mais le principal intérêt réside dans leurs taux d'infection.Pour les deux espèces il y eut des variations considérables entre les taux d'infection des échantillons recueillis et beaucoup de ces différences étaient persistantes sur plusieurs répétitions. Les femelles de G. pallidipes capturées sur les bufs et dans les pièges étaient plus infectées que celles capturées sur l'homme, sur le véhicule et au repos. Les mâles au repos de cette espèce avaient un taux d'infection élevé constant, tandis que les mâles capturés dans les pièges avaient le taux d'infection le plus élevé durant les premières captures et le plus bas durant les dernières captures. Les différences dans le taux d'infection étaient en liaison étroite avec les différences correspondantes dans l'âge moyen. Parmi les échantillons de G. pallidipes capturés sur bufs, et dans les pièges, les femelles avaient constamment un taux d'infection plus élevé que les mâles, tandis que parmi les captures sur le véhicule, sur l'homme, et chez les mouches au repos, les mâles avaient le taux d'infection le plus élevé.Les femelles de G. fuscipes capturées sur l'homme, et au repos avaient, avec une exception, des taux d'infection constamment plus élevés que celles recueillies par d'autres méthodes. Les mâles de cette espèce capturés buf au repos, sur véhicule et au repos avaient des taux d'infection constamment plus élevés. Le rapport entre l'âge moyen et le taux d'infection des différents échantillons était moins étroit que dans le cas de G. pallidipes.
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20.
This is the first report of the successful use of Pochonia chlamydosporia as a biological control agent against potato cyst nematodes (PCN) (Globodera pallida and G. rostochiensis) in potato crops grown under commercial field conditions and represents an important step in the development of biological control for PCN. Two field experiments were established in consecutive years (2006 and 2007) at different field sites in Shropshire, England. Treatments comprised of (1) untreated control, (2) P. chlamydosporia, (3) P. chlamydosporia with the nematicide fosthiazate and (4) fosthiazate alone. In both experiments, significant reductions in the nematode multiplication rate (Pf/Pi) for P. chlamydosporia treated plots were observed (48% and 51% control, respectively). The P. chlamydosporia treatment did not differ significantly from both fosthiazate treatments in terms of Pf/Pi in spite of the trend towards increased control particularly in Experiment 1. P. chlamydosporia therefore provided similar levels of nematode population control as fosthiazate. The combined treatment did not provide any additional reduction in Pf/Pi but demonstrated that P. chlamydosporia was compatible with fosthiazate. Over the different developmental stages of the juvenile nematodes, there was evidence of parasitism of adult females on the plant root by P. chlamydosporia. Root colonization by P. chlamydosporia was higher in the P. chlamydosporia treatment due to increased levels of nematodes in plant roots. Results from both experiments demonstrated the efficacy of P. chlamydosporia as a biological control agent of PCN and indicate its potential for use as part of an integrated pest management strategy.  相似文献   

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