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The little known ascaridoid nematode Raphidascaris (Ichthyascaris) lophii (Wu, 1949) is redescribed and illustrated based on newly collected specimens from the five different marine fishes: Lophius litulon (Jordan) (Lophiiformes: Lophiidae), Lophiomus setigerus (Vahl) (Lophiiformes: Lophiidae), Antennarius hispidus (Bloch et Schneider) (Lophiiformes: Antennaridae), Zeus faber Linnaeus (Zeiformes: Zeidae) and Ostichthys japonicus (Cuvier) (Beryciformes: Holocentridae) from the East and South China Sea. This species differs from all congeners in the subgenus Ichthyascaris by the length of the ventricular appendix (0.52–0.98 mm long), the number and arrangement of caudal papillae (26–32 pairs of precloacal, 3–4 pairs of paracloacal and 8–11 pairs of postcloacal) and the length of the spicules (0.49–0.88 mm long, representing 3.08–4.70% of body length). In addition, nematodes collected from these five different fishes have been characterized using molecular methods by sequencing and analysing the internal transcribed spacer (ITS) of ribosomal DNA. No variation in size and nucleotide polymorphisms is detected within the target sequence among all samples analysed. These data contribute to facilitate an accurate diagnosis of this poorly known nematode. An identification key to the species of the subgenus Ichthyascaris is also provided.
A new species of ascaridoid nematode, Hysterothylacium gibsoni sp. nov., is described based on specimens collected from the intestine of the slender lizardfish Saurida elongata (Temminck et Schlegel) (Aulopiformes: Synodontidae) in the Yellow Sea, China. The new species differs from its congeners by its small body size (12.8–13.2 mm), the absence of cervical alae, a very short intestinal caecum (representing 8.86–9.52% of oesophageal length) and a long ventricular appendix (intestinal caecum to ventricular appendix ratio 1:15.3–20.0), short spicules (0.38–0.41 mm, representing 2.97–3.11% of body length), the number and arrangement of the caudal papillae (25–28 pairs arranged as follows: 18–22 pairs precloacal, 3 pairs paracloacal, and 3–4 pairs postcloacal). In addition, Hysterothylacium tetrapteri (Bruce et Cannon, 1989) is also redescribed based on the material collected from the striped marlin Kajikia audax (Philippi) (Perciformes: Istiophoridae) in the South China Sea.
Cucullanus hainanensis sp. nov., collected from Muraenichthys gymnopterus (Bleeker) (Anguilliformes: Ophichthidae) in the South China Sea, was described using both light and scanning electron microscopy. The new species can be readily distinguished from its congeners by the large pseudobuccal capsule, the position of excretory pore and deirids, the length of spicules (0.64–0.76 mm, 5.84–6.67% of body length) and gubernaculum (0.21–0.24 mm), the number and arrangement of caudal papillae and the particular morphology of cloacal region in male. The new species was also characterized using molecular methods by sequencing and analysing the small subunit (18S) and the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA). In addition, Cucullanus muraenesocis (Yin et Zhang, 1983) was regarded a homonym of C. muraenesocis Yamaguti, 1961, and a new name, Cucullanus wangi nom. nov. was given to it.
Mawsonascaris parva sp. nov. collected from the Arabian whipray Himantura randalli Last, Manjaji-Matsumoto et Moore (Rajiformes: Dasyatidae) off the coast of Iraq is described and illustrated using light and scanning electron microscopy. The new species differs from its congeners by its small body size (8.11–18.2 mm long), the absence of an intestinal caecum, the slightly unequal spicules (left and right spicule 1.08–2.50 mm and 0.98–2.01 mm long, respectively, representing 12.1–13.7% and 10.1–12.1% of body length), the number and arrangement of male caudal papillae (13–14 pairs in total, arranged as: 7–8 pairs of precloacal, 1 pair of double paracloacal and 5 pairs of postcloacal) and the presence of a single, median precloacal papilla. Thus, a total of six species of Mawsonascaris are now known and this is the first species of this genus recorded from species of Himantura.
In order to evaluate the effects of different slope lengths (1, 2, 3, 4, and 5 m) and different vegetation coverage ratios (20%, 45%, 60%, and 90%) on the mechanisms of nutrient loss and runoff producing processes, we have conducted 14 simulated rainfall experiments. The results show that N and P loss are decided by the concentration and the runoff volume, but when the amounts of N and P in topsoil are small, their loss content mostly depends on runoff volume. Dissolved nitrogen is the main form in the nitrogen loss, while nitrate nitrogen is the main component in dissolved nitrogen, but the proportion in the total nitrogen gradually decreases with slope length increasing or with the increase of vegetation cover; the main form of phosphorus losses is particulate phosphorus, and the excessive sediment-bound nutrient loss released into water might cause secondary pollution of an aquatic environment.
The ethyl acetate fractions of aqueous extracts from two submerged macrophytes Potamogeton malaianus and Potamogeton maackianus were analyzed by gas chromatograph-mass spectrometry (GC-MS). The allelopathic activities and joint effects of the main components in ethyl acetate fractions on Microcystis aeruginosa were also determined. The results indicated that primary compositions in the ethyl acetate fractions were fatty acids, phenolic acids and hydroxy fatty acids that possessed antialgal activities. The joint effect assay for palmitic acid, benzoic acid and lactic acid showed that the additional effects were observed in the mixed organic acid, namely, the inhibitory effects of mixture groups were stronger than that of each compound alone on the growth of M. aeruginosa.
Thyroid hormones play an important role in regulating the metabolism and can affect the homeostasis of fat deposition. The gene encoding thyroglobulin (TG), producing the precursor for thyroid hormones, has been proposed as a positional and functional candidate gene for a QTL with an effect on fat deposition. In the present study, we identified 6 novel SNPs at the 3' flanking region of the TG gene. The SNP marker association analysis indicated that the SNP markers G133C, G156A, C220T and A506C were significantly associated with marbling score (P<0.05, N=271). Animals with the new homozygote genotype had higher marbling scores than those with the other genotypes. Besides, the linkage disequilibrium analysis indicated that these 4 SNPs were completely linked (r² -1). Results of this study suggest that the TG-gene-specific SNP may be a useful marker for meat quality traits in future marker-assisted selection programmes in beef cattle.
Gastric microbiota provides a biological barrier against the invasion of foreign pathogens from the oral cavity, playing a vital role in main-taining gastrointestinal health. Klebsiella spp. of oral origin causes various infections not only in gastrointestinal tract but also in other organs, with Klebsiella pneumoniae serotype K1 resulting in a liver abscess (KLA) through oral inoculation in mice. However, the relationship between gastric microbiota and the extra-gastrointestinal KLA infection is not clear. In our study, a 454 pyrosequencing analysis of the bacterial 16S rRNA gene shows that the composition of gastric mucosal microbiota in mice with or without KLA infection varies greatly after oral inoculation with K. pneumoniae serotype K1 isolate. Interestingly, only several bacteria taxa show a significant change in gastric mucosal microbiota of KLA mice, including the decreased abundance of Bacteroides, Alisptipes and increased abundance of Streptococcus. It is worth noting that the abundance of Klebsiella exhibits an obvious increase in KLA mice, which might be closely related to KLA infection. At the same time, the endogenous antibiotics, defensins, involved in the regulation of the bacterial microbiota also show an increase in stomach and intestine. All these findings indicate that liver abscess caused by K. pneumoniae oral inoculation has a close relationship with gastric microbiota, which might provide important information for future clinical treatment.
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