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New fish species and geographic records for Rhabdospora thelohani Laguessé, 1895 (rodlet cells) are presented. Additionally, the ultrastructure of R. thelohani in Alburnoides bipunctatus ohridanus Karaman, Borostomias antarcticus (L?nnberg), Leuciscus cephalus albus Bonaparte and Rutilus rubilio (Bonaparte) is compared with that reported by other authors and with members of Subphylum Apicomplexa. The ultrastructure of R. thelohani was similar in all the fish species examined; however, the organism was not present in all members of any single species and had intertissue density variations. Rhabdospora thelohani is pyriform, averaging in size 7 X 12 micrometer, with a basal nucleus. The surface complex is composed of a layer (0.5 micrometer diameter) formed by microfilaments (9.3 nm) and an outer trilaminar membrane (9.3 nm). The cytoplasm contains structures identical to rhoptries, micronemes and subpellicular microtubules. Mitochondria, Golgi apparatus, and rough endoplasmic reticulum were not observed, althouth free ribosomes were present and arranged in a vesicular pattern. The observations suggest that the organism moves between cell of epithelial layers and is either released into a lumen intact or passively or actively discharges its contents into a lumen. Results from this study indicate that R. thelohani should be considered a member of Apicomplexa unless definitive evidence is presented to the contrary. 相似文献
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Md. Ashekur Rahman Md. Yeamin Hossain Sumaya Tanjin Zannatul Mawa Md. Rabiul Hasan Kazi Ahsan Habib Jun Ohtomi 《Zeitschrift fur angewandte Ichthyologie》2021,37(2):364-366
Length weight relationships (LWR) of five marine fishes were estimated from the Bay of Bengal, Bangladesh. Fish samples were collected occasionally from fisher's catch with gill net (mesh size: 3 cm) during November 2019 to October 2020. Fishing was done overnight. Total length (0.1 cm) and body weight (0.01 g) of each individual were measured. We recorded maximum total length for P. maculatus (55.0 cm) and P. parmatus (39.0 cm). 相似文献
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The biodiversity assessment of different taxa of the genus Caulerpa is of interest from the context of morphological plasticity, invasive potential of some species and biotechnological and pharmacological applications. The present study investigated the identification and molecular phylogeny of different species of Caulerpa occurring along the Indian coast inferred from tufA, rbcL, 18S rDNA and ITS rDNA nucleotide sequences. Molecular data confirmed the identification of 10 distinct Caulerpa species: C. veravalensis, C. verticillata, C. racemosa, C. microphysa, C. taxifolia, C. sertularioides, C. scalpelliformis, C. serrulata, C. peltata and C. mexicana. All datasets significantly supported the sister relationship between C. veravalensis and C. racemosa var. cylindracea. It was also concluded from the results that the specimen identified previously as C. microphysa and C. lentillifera could not be considered as separate species. The molecular data revealed the presence of multiple lineages for C. racemosa which can be resolved into separate species. All four markers were used to ascertain their utility for DNA barcoding. The tufA gene proved a better marker with monophyletic association as the main criteria for identification at the species level. The results also support the use of 18S rDNA insertion sequences to delineate the Caulerpa species through character-based barcoding. The ITS rDNA (5.8S-ITS2) phylogenetic analysis also served as another supporting tool. Further, more sequences from additional Caulerpa specimens will need to be analysed in order to support the role of these two markers (ITS rDNA and 18S insertion sequence) in identification of Caulerpa species. The present study revealed the phylogeny of Caulerpa as complete as possible using the currently available data, which is the first comprehensive report illustrating the molecular phylogeny and barcoding of the genus Caulerpa from Indian waters. 相似文献
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Ucheor B. Choi Rashek Kazi Natalie Stenzoski Lonnie P. Wollmuth Vladimir N. Uversky Mark E. Bowen 《The Journal of biological chemistry》2013,288(31):22506-22515
The NMDA-sensitive glutamate receptor is a ligand-gated ion channel that mediates excitatory synaptic transmission in the nervous system. Extracellular zinc allosterically regulates the NMDA receptor by binding to the extracellular N-terminal domain, which inhibits channel gating. Phosphorylation of the intrinsically disordered intracellular C-terminal domain alleviates inhibition by extracellular zinc. The mechanism for this functional effect is largely unknown. Proline is a hallmark of intrinsic disorder, so we used proline mutagenesis to modulate disorder in the cytoplasmic domain. Proline depletion selectively uncoupled zinc inhibition with little effect on receptor biogenesis, surface trafficking, or ligand-activated gating. Proline depletion also reduced the affinity for a PDZ domain involved in synaptic trafficking and affected small molecule binding. To understand the origin of these phenomena, we used single molecule fluorescence and ensemble biophysical methods to characterize the structural effects of proline mutagenesis. Proline depletion did not eliminate intrinsic disorder, but the underlying conformational dynamics were changed. Thus, we altered the form of intrinsic disorder, which appears sufficient to affect the biological activity. These findings suggest that conformational dynamics within the intrinsically disordered cytoplasmic domain are important for the allosteric regulation of NMDA receptor gating. 相似文献
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Nicotinic acetylcholine receptors (nAChRs) at zebrafish red and white muscle show different properties during development 下载免费PDF全文
Nicotinic acetylcholine receptors (nAChRs) are highly expressed at the vertebrate neuromuscular junction (NMJ) where they are required for muscle activation. Understanding the factors that underlie NMJ development is critical for a full understanding of muscle function. In this study we performed whole cell and outside‐out patch clamp recordings, and single‐cell RT‐qPCR from zebrafish red and white muscle to examine the properties of nAChRs during the first 5 days of development. In red fibers miniature endplate currents (mEPCs) exhibit single exponential time courses at 1.5 days postfertilization (dpf) and double exponential time courses from 2 dpf onwards. In white fibers, mEPCs decay relatively slowly, with a single exponential component at 1.5 dpf. By 2 and 3 dpf, mEPC kinetics speed up, and decay with a double exponential component, and by 4 dpf the exponential decay reverts back to a single component. Single channel recordings confirm the presence of two main conductance classes of nAChRs (~45 pS and ~65 pS) in red fibers with multiple time courses. Two main conductance classes are also present in white fibers (~55 pS and ~73 pS), but they exhibit shorter mean open times by 5 dpf compared with red muscle. RT‐qPCR of mRNA for nicotinic receptor subunits supports a switch from γ to ε subunits in white fibers but not in red. Our findings provide a developmental profile of mEPC properties from red and white fibers in embryonic and larval zebrafish, and reveal previously unknown differences between the NMJs of these muscle fibers.© 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 916–936, 2016 相似文献
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Katie N. Kang Dustin R. Klein Misha I. Kazi Franois Gurin Vincent Cattoir Jennifer S. Brodbelt Joseph M. Boll 《Molecular microbiology》2019,111(6):1604-1616
The Enterobacter cloacae complex (ECC) consists of closely related bacteria commonly associated with the human microbiota. ECC are increasingly isolated from healthcare‐associated infections, demonstrating that these Enterobacteriaceae are emerging nosocomial pathogens. ECC can rapidly acquire multidrug resistance to conventional antibiotics. Cationic antimicrobial peptides (CAMPs) have served as therapeutic alternatives because they target the highly conserved lipid A component of the Gram‐negative outer membrane. Many Enterobacteriaceae fortify their outer membrane with cationic amine‐containing moieties to prevent CAMP binding, which can lead to cell lysis. The PmrAB two‐component system (TCS) directly activates 4‐amino‐4‐deoxy‐l ‐arabinose (l ‐Ara4N) biosynthesis to result in cationic amine moiety addition to lipid A in many Enterobacteriaceae such as E. coli and Salmonella. In contrast, PmrAB is dispensable for CAMP resistance in E. cloacae. Interestingly, some ECC clusters exhibit colistin heteroresistance, where a subpopulation of cells exhibit clinically significant resistance levels compared to the majority population. We demonstrate that E. cloacae lipid A is modified with l ‐Ara4N to induce CAMP heteroresistance and the regulatory mechanism is independent of the PmrABEcl TCS. Instead, PhoPEcl binds to the arnBEcl promoter to induce l ‐Ara4N biosynthesis and PmrAB‐independent addition to the lipid A disaccharolipid. Therefore, PhoPQEcl contributes to regulation of CAMP heteroresistance in some ECC clusters. 相似文献