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Mangroves perform a crucial ecological role along the tropical and subtropical coastal intertidal zone where salinity fluctuation occurs frequently. However, the differential responses of mangrove plant at the combined transcriptome and metabolome level to variable salinity are not well documented. In this study, we used Avicennia marina (Forssk.) Vierh. a pioneer species of mangrove wetlands and one of the most salt-tolerant mangroves, to investigate the differential salt tolerance mechanisms under low and high salinity using inductively coupled plasma-mass spectrometry, transcriptomic and metabolomic analysis. The results showed that HAK8 was up-regulated and transported K+ into the roots under low salinity. However, under high salinity, AKT1 and NHX2 were strongly induced, which indicated the transport of K+ and Na+ compartmentalization to maintain ion homeostasis. In addition, A. marina tolerates low salinity by up-regulating ABA signaling pathway and accumulating more mannitol, unsaturated fatty acids, amino acids' and L-ascorbic acid in the roots. Under high salinity, A. marina undergoes a more drastic metabolic network rearrangement in the roots, such as more L-ascorbic acid and oxiglutatione were up-regulated, while carbohydrates, lipids and amino acids were down-regulated in the roots, and, finally, glycolysis and TCA cycle were promoted to provide more energy to improve salt tolerance. Our findings suggest that the major salt tolerance traits in A. marina can be attributed to complex regulatory and signaling mechanisms, and show significant differences between low and high salinity. [ABSTRACT FROM AUTHOR]

Salt secretion is an important strategy used by the mangrove plant Aegiceras corniculatum to adapt to the coastal intertidal environment. However, the structural, developmental and functional analyses on the leaf salt glands, particularly the salt secretion mechanism, are not well documented. In this study, we investigated the structural, developmental and degenerative characteristics and the salt secretion mechanisms of salt glands to further elucidate the mechanisms of salt tolerance of A. corniculatum. The results showed that the salt gland cells have a large number of mitochondria and vesicles, and plenty of plasmodesmata as well, while chloroplasts were found in the collecting cells. The salt glands developed early and began to differentiate at the leaf primordium stage. We observed and defined three stages of salt gland degradation for the first time in A. corniculatum , where the secretory cells gradually twisted and wrinkled inward and collapsed downward as the salt gland degeneration increased and the intensity of salt gland autofluorescence gradually diminished. In addition, we found that the salt secretion rate of the salt glands increased when the treated concentration of NaCl increased, reaching the maximum at 400 mM NaCl. The salt-secreting capacity of the salt glands of the adaxial epidermis is significantly greater than that of the abaxial epidermis. The real-time quantitative PCR results indicate that SAD2 , TTG1 , GL2 and RBR1 may be involved in regulating the development of the salt glands of A. corniculatum. Moreover, Na+/H+ antiporter, H+-ATPase, K+ channel and Cl− channel may play important roles in the salt secretion of salt glands. In sum mary, this study strengthens the understanding of the structural, developmental and degenerative patterns of salt glands and salt secretion mechanisms in mangrove recretohalophyte A. corniculatum , providing an important reference for further studies at the molecular level. [ABSTRACT FROM AUTHOR]

Avicennia marina , a mangrove plant growing in coastal wetland habitats, is frequently affected by tidal salinity. To understand its salinity tolerance, the seedlings of A. marina were treated with 0, 200, 400 and 600 mM NaCl. We found the whole-plant dry weight and photosynthetic parameters increased at 200 mM NaCl but decreased over 400 mM NaCl. The maximum quantum yield of primary photochemistry (Fv/Fm) significantly decreased at 600 mM NaCl. Transmission electron microscopy observations showed high salinity caused the reduction in starch grain size, swelling of the thylakoids and separation of the granal stacks, and even destruction of the envelope. In addition, the dense protoplasm and abundant mitochondria in the secretory and stalk cells, and abundant plasmodesmata between salt gland cells were observed in the salt glands of the adaxial epidermis. At all salinities, Na+ content was higher in leaves than in stems and roots; however, Na+ content increased in the roots while it remained at a constant level in the leaves over 400 mM NaCl treatment, due to salt secretion from the salt glands. As a result, salt crystals on the leaf adaxial surface increased with salinity. On the other hand, salt treatment increased Na+ and K+ efflux and decreased H+ efflux from the salt glands by the non-invasive micro-test technology, although Na+ efflux reached the maximum at 400 mM NaCl. Further real-time quantitative PCR analysis indicated that the expression of Na+/H+ antiporter (SOS1 and NHX1), H+-ATPase (AHA1 and VHA-c1) and K+ channel (AKT1 , HAK5 and GORK) were up-regulated, and only the only Na+ inward transporter (HKT1) was down-regulated in the salt glands enriched adaxial epidermis of the leaves under 400 mM NaCl treatment. In conclusion, salinity below 200 mM NaCl was beneficial to the growth of A. marina , and below 400 mM, the salt glands could excrete Na+ effectively, thus improving its salt tolerance. [ABSTRACT FROM AUTHOR]

Thirty 2-year old transgenic carp individuals with growth hormone gene of salmon were randomly selected to study the affecting degree of their phenotypic traits on their body mass by the methods of correlation and path analyses, with 30 individuals of non-transgenic carp as the control, aimed to ascertain the main phenotypic parameters affecting the body mass of the transgenic and non-transgenic carps. The test phenotypic traits were total length, body length, body height, least height of caudal peduncle, length of caudal peduncle, length of head, snout length, eyes horizontal diameter, inter-orbital distance, and body depth. Correlation analysis showed that for both of the transgenic and non-transgenic carps, most of the test phenotypic parameters were significantly correlated to body mass (P<0.01). Path analysis indicated that for transgenic carp, its body length and body height were the main predictable factors affecting body mass, with the path coefficient being 0.572 and 0.415, respectively, while for non-transgenic carp, its body depth and tail length were the main predictable factors affecting body mass, with the path coefficient being 0.610 and 0.377, respectively. [ABSTRACT FROM AUTHOR]

Thirty 2-year old transgenic carp individuals with growth hormone gene of salmon were randomly selected to study the affecting degree of their phenotypic traits on their body mass by the methods of correlation and path analyses, with 30 individuals of non-transgenic carp as the control, aimed to ascertain the main phenotypic parameters affecting the body mass of the transgenic and non-transgenic carps. The test phenotypic traits were total length, body length, body height, least height of caudal peduncle, length of caudal peduncle, length of head, snout length, eyes horizontal diameter, inter-orbital distance, and body depth. Correlation analysis showed that for both of the transgenic and non-transgenic carps, most of the test phenotypic parameters were significantly correlated to body mass (P<0.01). Path analysis indicated that for transgenic carp, its body length and body height were the main predictable factors affecting body mass, with the path coefficient being 0.572 and 0.415, respectively, while for non-transgenic carp, its body depth and tail length were the main predictable factors affecting body mass, with the path coefficient being 0.610 and 0.377, respectively.

In this study, 26 candidate genes were quantified and normalized in the brain cDNA of common carp (Cyprinus carpio) at 23°C and 6°C using double-standard curve method of real-time quantitative PCR. The results showed that five candidates up-regulated in the samples at 6°C (P<0.01) and quantified 2.11, 13.9, 2.52, 7.38, and 1.83 times more than in the samples at 23°C, respectively. Gene function searching indicated that the protein products of these five candidates were elongation of very long chain fatty acids protein, Acyl-CoA desaturase, Transcription initiation factor IIB, Myo-inositol- 1-phosphate synthase, and Blood-brain barrier HT7 antigen individually. Moreover, seven down-regulated candidates were also identified in the same samples at 6°C (P>0.05), and their expression levels were decreased by 21.8%, 25.9%, 16.6%, 23.7%, 15.8%, 16.3%, and 42.5%, respectively, in comparison with the samples at 23°C. These seven down-regulated candidates mainly participated in the inhibition of glycolysis, improvement of cell apoptosis, and intervention of synapse remodeling based on the results of function searching. The five cold-induced genes identified in this study will be used as important elements for fish with cold sensitive through transgenic technology in future.

Cold tolerance is one of the major economic characters in fish. In order to discuss the cold tolerance of large yellow croaker (Pseudosciaena crocea R.), fifteen fluorescent dye-labeled microsatellite markers were applied to detect genetic differences between F1 offsprings of cold tolerance group and normal group of large yellow croaker by SSR-PCR. Each group contained 20 randomly and separately sampled individuals. As a result, marker LYC0002 five alleles (LYC0002(104 bp), LYC0002(106 bp), LYC0002(108 bp), LYC0002(110 bp), and LYC0002(112 bp)) were amplified with marker LYC0002 in both groups and 60% (12/20) of individuals had allele LYC0002(112 bp) in cold tolerance group exclusively, which indicated that this allele is probably sensitive to temperature and associated with gene for cold tolerance. In addition, four alleles (LYC0002(106 bp), LYC0002(108 bp), LYC0002(110 bp), and LYC0002(112 bp)) were sequenced individually. Sequence alignments showed that LYC0002(112 bp) allele contains 10 (CA) repeats, the remaining three alleles lacked one (CA) one by one, corresponding to the stepwise mutation model (SMM) of microsatellite.