Molecular structure and expression patterns of flounder (Paralichthys olivaceus) Myf-5, a myogenic regulatory factor

Myf-5, a member of the myogenic regulatory factors (MRF), has been shown to be expressed in muscle precursors in early stage zebrafish embryos. The MRFs, including MyoD, Myf-5, Myogenin and MR-F4, belong to the basic Helix-Loop-Helix transcription factors that contain a conserved basic Helix-Loop-Helix (bHLH) domain. To better understand the role of Myf-5 in the development of fish muscles, we have isolated the Myf-5 genomic sequence and cDNA from Flounder (Paralichthys olivaceus), and analyzed its structures and patterns of expression. Promoter analysis identified several putative transcription factor binding sites such as an E-box, NF-Y sites that might confer muscle-specific expression. Myf-5 transcripts were first detected in the paraxial mesoderm that gives rise to slow muscles. During somitogenesis, Myf-5 expression was found in developing somites. Myf-5 expression decreased gradually in somites in the anterior region, but remained strong in the newly formed somites. In the hatching stage, the expression was also detected in other muscle cells such as head muscle and fin muscle. In the growing fish, RT-PCR results showed that Myf-5 was expressed in the skeletal muscle and intestine. (c) 2006 Elsevier Inc. All rights reserved.

Molecular cloning and expression analysis of Crustin-like gene from Chinese shrimp Fenneropenaeus chinensis

A new member of antimicrobial protein genes of the Crustin family was cloned from haemocytes of the Chinese shrimp Fenneropenaeus chinensis by 3' and 5' RACE. The full-length cDNA of Crustin-like gene contains a 390 bp open reading frame, encoding 130 amino acids. The deduced peptide contains a putative signal peptide of 17 amino acids and mature peptide of 113 amino acids. The molecular mass of the deduced mature peptide is 12.3 ku. It is highly cationic with a theoretical isoelectric point of 8.5. The deduced amino acids sequence of this Crustin showed high homology with those of Penaeus (Litopenaeas) setferus. Northern blotting showed that the cloned Crustin gene was mainly expressed in haemocytes, gill, intestine, and RNA in situ hybridization indicated that the Crustin gene was constitutively expressed exclusively in haemocytes of these tissues. Capillary electrophoresis RT-PCR analysis showed that Crustin was up-regulated dramatically from 12 to 48 h after a brief decrease of mRNA during first 6 h in response to microbe infection. The level of Crustin mRNA began to restore at 72 h post-challenge. This indicated that Crustin gene might play an important role when shrimps are infected by bacterial pathogen.

Digestive gut structure and activity of protease, amylase, and alkaline phosphatase in Calanus sinicus during summer in the Yellow Sea and the East China Sea

Calanus sinicus aggregate at the depth of 40-60 m (ambient temperature is 16 degreesC) in the waters of the continental shelf of the Yellow Sea during summer. in animals found in near shore regions, there are changes in digestive gut cells structure, digestive enzyme activity (protease, amylase), and tissue enzyme (alkaline phosphatase (ALP)), which may represent adaptations by this cold-water animal to a sharp seasonal increase in temperature of 6-23 degreesC. The activities of the digestive enzymes (protease and amylase) are very low in animals at stations near the estuary of Yangtse River, whereas they are relatively high in animals at stations in the central Yellow Sea, During summer, B-cells of the intestine and the villi intestinalis disappear in animals that do not feed at stations near the estuary of the Yangtse River. Respiration rates were undetectable or quite low during summer in C. sinicus from stations near the estuary of the Yangtse River, whereas they were relatively high at stations in the central Yellow Sea. Based upon the morphological characteristics of the digestive gut structure, enzyme levels, respiration rates, and the distribution of C. sinicus, we concluded that C. sinicus might be dormant during summer in the near shore areas of the East China Sea while remaining active in the central Yellow Sea. (C) 2002 Elsevier Science B.V. All rights reserved.

Transfer of paralytic shellfish toxins via marine food chains: A simulated experiment

Objective To study the transfer of paralytic shellfish toxins (PST) using four simulated marine food chains: dinoflagellate Alexandrium tamarense -> Arterriia Artemia salina -> Mysid shrimp Neomysis awatschensis; A. tamarense-N. awatschensis: A. taniarense A. salina -> Perch Lateolabrax japonicus; and A. tamarense -> L. japonicus. Methods The ingestion of A. tamarense, a producer of PST, by L. japonicus, N. awatschensis, and A. salina was first confirmed by microscopic observation of A. tamarense cells in the intestine samples of the three different organisms, and by the analysis of Chl.a levels iii the samples. Toxin accumulation in L. japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly ibrough the vector of A. salina was then studied. The toxicity of samples was measured using the AOAC mouse bioassay method, and the toxin content and profile of A. tamarense were analyzed by the HPLC method. Results Both A. salina and N. awatschensis could ingest A. tamarense cells. However, the ingestion capability of A. salina exceeded that of N. awatschensis. After the exposure to the culture of A. tamarense (2 000 cells(.)mL(-1)) for 70 minutes, the content of ChLa in A. salina and N. awatschensis reached 0.87 and 0.024 mu g-mg(-1), respectively. Besides, A. tamarense cells existed in the intestines of L. japonicus, N. awatschensis and A. salina by microscopic observation. Therefore, the three organisms could ingest A. tamarense cells directly. A. salina could accumulate high content of PST, and the toxicity of A. salina in samples collected on days 1, 4, and 5 of the experiment was 2.18, 2.6, and 2.1 MU(.)g(-1), respectively. All extracts from the samples could lead to death of tested mice within 7 minutes, and the toxin content in arternia sample collected on the 1st day was estimated to be 1.65x10(-5) pg STX equa Vindividual. Toxin accumulation in L. japonicus and N. awatschensis directly from the feeding on A. tamarense or indirectly froin the vector of A. salina was also studied. The mice injected with extracts from L. japonicus and N. awatschensis samples that accumulated PST either directly or indirectly showed PST intoxication symptoms, indicating that low levels of PST existed in these samples. Conclusion Paralytic shellfish toxins can be transferred to L. japonicus, N. awatschensis, and A. salina from A. taniarense directly or indirectly via the food chains.