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1.
The androgenic gland(AG) is an important endocrine gland for male reproductive function in crustaceans. In the present study, we investigated the histological characteristics of the androgenic gland of peppermint shrimp, Lysmata wurdemanni. The peppermint shrimp matures as male first, then some individuals may become euhermaphrodite after several moltings(transitional phase). Euhermaphrodite-phase shrimp acts as male at intermolts. However, it can be fertilized as a female immediately after molting. Considering the male reproductive function acts in its lifespan except for at larval stages, and female reproductive system starts to develop at transitional phase, we hypothesized that AG activity might be reduced to allow and promote vitellogenesis onset in early transitional phase and the following euhermaphrodite phase. So AG cell structure might be different in three phases in L. wurdemanni. The results showed that AG exists in the male in transitional and euhermaphrodite phases. The gland cell clusters surrounding the ejaculatory ducts locate at the roots of the fifth pereopods. The nucleus diameters are similar in the three phases while the nucleus-to-cell ratio is the lowest in euhermaphrodite phase. Our results indicated that for the individuals that will become euhermaphrodite, the cellular structure of AG changes since transitional phase. Male reproductive function which is still available in euhermaphrodite-phase shrimp should be due to the existence of the gland. 相似文献
2.
1 INTRODUCTION Ovarian development of female crustaceans is under the direct regulations of two neurohormones: gonad-inhibiting hormone (GIH) secreted by optic ganglia and gonad-stimulating hormone (GSH) se- creted by brain and thoracic ganglia (Fingerman… 相似文献
3.
The appropriate reference gene is a prerequisite for accurate normalization of gene expression level, and research on suitable reference genes in clam Cyclina sinensis is scarce. To improve the situation, we selected five commonly used housekeeping genes, including β-actin, Elongation factor 1-α (EF1-α), Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), 40S ribosomal protein S18 (RPS18), and Tubulin α (TUB-α), then evaluated their expression stability in different adult tissues and under different experimental treatments (salinity stress and Vibrio parahaemolyticus infection). Their expression stability was analyzed by three frequently used programs, geNorm, NormFinder, and BestKeeper. This analysis indicated that multiple genes should be used for normalization, and we concluded that the reference gene combination GAPDH-RPS18-β-actin, should be used for qRT-PCR analysis in different tissues of C. sinensis under normal physiological conditions. For the clams under salinity stress and Vibrio infection, EF1-α-GAPDH-RPS18 was recommended as the gene combination for qRT-PCR normalization. TUB-α was generally poorly ranked by all programs, and should not be used in future studies. This study should provide fundamental support for accurate quantitative gene expression analysis of this species. 相似文献
4.
Monthly investigations were mae on the population of Chinese freshwater crab, Sinopotamon yangtsekiense Bott, 1967 from April, 1984 to March, 1985. The data on 4413 specimens show that the growth was affected mainly by temperature.
During the April to November growth period, the crabs' major development occurred from June through October. One year was
required for a fine white oocyte to develop into a mature egg. The reproduction period was June–October. Females bearing eggs
were taken from June–August, and crabs with young were found from July–October. The females reproduced once a year but could
for more than one year. The number of eggs carried by a female varied greatly according to the size of the crab, ranging from
30 to 100 eggs. New-born crabs become mature after 1–2 years. The sex ratio was approximately 1∶1 in the overall population.
However, the larger crabs are predominantly male. The age distribution of S. yangtsekinese was estimated from size frequency histograms. There were more adult crabs (over 70%) from June to October and more immature
crabs (over 50%) from November to May. 相似文献
6.
We constructed and characterized a normalized cDNA library of Nannochloropsis oculata CS-179, and obtained 905 nonredundant sequences (NRSs) ranging from 431–1 756 bp in length. Among them, 496 were very similar
to nonredundant ones in the GenBank ( E ≤1.0e-05), and 349 ESTs had significant hits with the clusters of eukaryotic orthologous groups (KOG). Bases G and/or C at
the third position of codons of 14 amino acid residues suggested a strong bias in the conserved domain of 362 NRSs (>60%).
We also identified the unigenes encoding phosphorus and nitrogen transporters, suggesting that N. oculata could efficiently transport and metabolize phosphorus and nitrogen, and recognized the unigenes that involved in biosynthesis
and storage of both fatty acids and polyunsaturated fatty acids (PUFAs), which will facilitate the demonstration of eicosapentaenoic
acid (EPA) biosynthesis pathway of N. oculata. In comparison with the original cDNA library, the normalized library significantly increased the efficiencies of random
sequencing and rarely expressed genes discovering, and decreased the frequency of abundant gene sequences. 相似文献
8.
There are rising concerns about the hazardous effects of heavy metals on the environment. In this study, comet assay and DNA alkaline unwinding assay were conducted on the tissues (gills, hepatopancreas, and hemocytes) of Charybdis japonica in order to illustrate genotoxicity of three heavy metal ions (Cu2+, Pb2+, and Cd2+) on the marine crabs C. japonica. The crabs were exposed to Cu2+ (10, 50, and 100 ?g.L?1), Pb2+ (50, 250, and 500 ?g L?1) and Cd2+ (5, 25, and 50 ?g L?1), and the tissues were sampled at days 0.5, 1, 3, 6, 9, and 15. DNA alkaline unwinding assay was used for testing the DNA single strand break in gills and hepatopancreas and comet assay was employed for testing the DNA damage in hemocytes. The results showed that the DNA damage (F-value) of gills in the crabs exposed to the three heavy metals was decreased gradually during the exposure periods and there was a dose-time response relationship in certain time, suggesting that the levels of DNA single strand break in all the experimental groups increased significantly compared to the controls. Changes of F-value in hepatopancreas of the crabs exposed to the three heavy metals were similar to those in gills except that the peak values were found in the 500 ?g L?1 Pb2+ treatment group at day 3 and the 50 ?g L?1 Cd2+ treatment group at day 9. The ranks of DNA damage in gills and hepatopancreas induced by the three heavy metal ions (50 ?g L?1, day 15) were Cd2+ >Pb2+ >Cu2+ and Pb2+ >Cu2+ >Cd2+. The levels of DNA damage in gills were higher than those in hepatopancreas in the same experimental group. It can be concluded that indices of DNA damage can be used as the potential biomarkers of heavy metal pollution in marine environment. 相似文献
12.
Pectenotoxins (PTXs) are a group of marine algal toxins. In this study, the accumulation and depuration of pectenotoxins in
brown crab Cancer pagurus were investigated. Crabs were fed with toxic blue mussels Mytilus edulis for 21 days and then depurated for 42 days. Toxins were extracted with methanol from the digestive glands of contaminated
crabs, uncontaminated crabs (control group) and from blue mussels for comparison. Extracts were analyzed by liquid chromatograph
coupled with tandem mass spectrometry (LC-MS-MS). The concentrations of PTX-2, PTX-2 SA, 7- epi-PTX-2 SA, and PTX-12 were analyzed in two batches of toxic blue mussels and the crabs. A one-compartment model was applied
to describe the depuration of PTXs. The half-life of PTXs was estimated to be 6–7.5 days. After depuration for 42 days, the
amount of PTXs measured in the crab digestive glands was less than 1 μg/kg.
Supported by Norwegian Education Funding “Quata”(2005) 相似文献
13.
A genetic transformation model for the seaweedLaminaria japonica mainly includes the following aspects:
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1.
The method to introduce foreign genes into the kelp,L. japonica
Biolistic bombardment has been proved to be an effective method to bombard foreign DNA through cell walls into intact cells of both sporophytes and gametophytes. The expression ofcat andlacZ was detected in regenerated sporophytes, which suggests that this method could induce random integration of foreign genes.
Promoters to drive gene expression
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2.
The CaMV35S promoter was first used by us to induce the expression of GUS gene in brown algae. But results of further studies suggested that CaMV35S could be a tissue-specific promoter. Our use of SV40 promoter resulted in both transient and stable expression oflacZ andcat in sporophytes or gametophytes. No GUS or LacZ background was found in either sporophytes or gametophytes.The regeneration route of transgenic kelp
The regeneration efficiency of explants is still very low. By using female gametophytes as gene hosts and parthenogenesis as regeneration route, CAT activity and LacZ activity were detected in regenerated sporophytes of parthenogenetic kelp. li]4.|The way to select transgenic kelp
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1.
Results of sensitivity tests showed that kelp was only sensitive to chloramphenicol and hygromycin among many antibiotics. The regenerated sporophytes by parthenogenesis were more sensitive to hygromycin than to chloramphenicol. Resistant kelp was created by transforming female gametophytes with pSV40-CAT and stimulating parthenogenesis followed by selection in medium with lethal concentration of chloramphenicol.
Safety consideration of transgenic kelp
L. japonica was originally introduced from Japan. In China it is a cultured population. The possibility of its negative impact on natural populations is very low. 2) The vectors and target genes used for transformation should be restricted in order to avoid any negative impacts on human health and environment. 3) Specially devised containers (3.6 L, made of 200 μm membrane) were used to ensure that the kelp cannot escape or be eaten by marine animals. 4) To avoid the release of spores, it is very necessary to harvest the kelp at suitable age before the sporangium forms.
相似文献
15.
We studied the effects of mercury (Hg 2+) on antioxidant and digestive enzyme activities in terms of LC 50 value and on hepatopancreas histostructures of juvenile Chinese mitten crabs Eriocheir sinensis in 40-day exposure to various concentrations of Hg 2+ (0, 0.01, 0.05, 0.10, 0.20, and 0.30 mg/L). The results show that the activities of superoxide dismutase (SOD), glutathione
peroxidase (GPX) and catalase (CAT) significantly increased in the concentrations of 0.01 and 0.05 mg/L, while that of enzyme
decreased in 0.10, 0.20 and 0.30 mg/L treatments. Meanwhile, Hg 2+ disrupted the histostructures of the hepatopancreas, causing decreases in activities of pepsin, tryptase, amylase, and cellulose,
which are synthesized in the hepatopancreas. Moreover, as the Hg 2+ concentration increased, the survival rate of the crabs decreased, worst at 56.57% in 0.30 mg/L. Therefore, although crabs
are able to tolerate low levels of mercury pollution, high levels lead to cellular injury and tissue damage in hepatopancreas,
which then loses some of its vital physiological functions such as absorption, storage, and secretion. 相似文献
16.
通过显微观察和组织学连续切片,对凡纳滨对虾的促雄性腺进行研究。结果表明:凡纳滨对虾的促雄性腺埋于精荚囊端壶腹外侧的肌肉中,呈不规则的块状,Harris苏木精染色呈嗜碱性。H?E染色显示,促雄性腺主要由两种形态的细胞构成,一种核质致密嗜碱性非常强,细胞核被染成深蓝色,核仁很难辨认,大多呈圆形或卵圆形(A型细胞);另一种细胞多为卵圆形,细胞核较大,核质疏松,被染成浅蓝色,核仁1～2个清晰可见(B型细胞)。此外,促雄性腺中A、B细胞的出现及其数量随精巢发育而发生变化,繁殖完成后细胞解体。 相似文献
17.
A full life-cycle toxicity test, combined with histology, on calanoid copepod Schmackeria poplesia was used to study the effect of bis(tributyltin) oxide (TBTO). The results indicate no sex-specific differences in TBTO toxicity.
Long-term mortalities of the copepods exposed to concentrations higher than 20 ng TBTO L −1 were significantly elevated compared with that of control, and larval development was inhibited when they were exposed to
40 and 60 ng TBTO L −1. The percentages of ovigerous females were reduced compared with the control ( P<0.01) after 24 days exposure to concentrations higher than 10 ng TBTO L −1. Histological examinations suggest that exposure to TBTO might block the posterior end of the diverticula and inhibits the
production of egg sacs. A modified Euler-Lotka equation was used to calculate a population-level endpoint, the intrinsic rate
of natural increase ( r
m), from individual life-table endpoints, i.e. mortality rate, time of release of first brood, sex ratio, the fraction of ovigerous
females among all females as well as the number of nauplii per ovigerous female. Apart from the highest TBTO concentration
(60 ng L −1), where all females aborted their egg sacs, 20 ng TBTO L −1 was the only concentration that significantly decreased r
m compared with that of control (an effect associated with decreased sex ratio). The results show that the S. poplesia is affected by prolonged exposure to low concentrations of TBTO. The full life-cycle toxicity test combined with histology
experiments provides more integral understanding of the toxicity of endocrine disrupters. 相似文献
18.
To investigate the stimulating effects of immunostimulants on the autogenous immunocompetence of crabs and the possible mechanisms
involved, the immunostimulating effects of β-1,3-glucan, lipopolysaccharide (LPS), inactivated Vibrio harveyi and Vibrio anguillarum on phenoloxidase (PO) and hemocytes of Charybdis japonica were investigated in this study. It was found that the yields and the enzymatic activities of purified PO in C. japonica increased significantly after the crabs were treated with immunostimulants, while the unit enzymatic activities remained
almost the same. After treatment with β-1,3-glucan and LPS, the amount of rough endoplasmic reticulum (RER) and the number
of mitochondria in both semigranular cells and granular cells increased greatly, and the number of cytoplasmic granules decreased
but with enlarged volume. However, the corresponding characteristics of hyaline cells remained almost the same. On the other
hand, the number of granules in semigranular cells decreased greatly, and the number of mitochondria of hyaline cells increased
greatly, after treatment with inactivated vibrios. It may be concluded that the effect of polysaccharide immunostimulants
on the innate immune system of C. japonica is different from that of inactivated vibrio immunostimulants. The immunity-enhancing mechanism of polysaccharides in crab
autogenous immunocompetence is probably accomplished by the increased yields of PO and total PO activities, while that of
inactivated vibrios is probably accomplished by the partially increased yields of PO and total PO activities as well as the
significantly improved phagocytotic abilities of semigranular cells and hyaline cells. 相似文献
19.
The genes coding for the α-and β-subunit of allophycocyanin (apcA andapcB) from the cyanophyteSpirulina maxima were cloned and sequenced. The results revealed 44.4% of nucleotide sequence similarity and 30.4% of similarity of deduced amino acid sequence between them. The amino acid sequence identities betweenS. maxima andS. platensis are 99.4% for α subunit and 100% for β subunit. 相似文献
20.
The complete mitogenome of Parachiloglanis hodgarti was sequenced and characterized, which is the first mitogenome of the genus Parachiloglanis within Sisoridae. The mitogenome is 16 511-bp long and included 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and one control region. The genome composition was A+T biased (58.64%) and exhibited a positive AT-skew (0.095) and a negative GC-skew (?0.283). Compared with other Sisoridae fishes, the characteristics of nucleotide skews, codon usage, and amino acid usage of the P. hodgarti mitogenome are more similar to those of non-Glyptosternoid fishes. Furthermore, the phylogenetic trees show that Sisoridae fishes fall into four major clades and P. hodgarti (Clade I) is basal to the Sisoridae family, forming a sister clade to the Glyptosternoids (Clade IV). The topological structures constructed in this study raised doubts over the traditional classification system. These results will help better understand the features of the P. hodgarti mitogenome and provide a reference for further phylogenetic research on Sisoridae species. 相似文献
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