Cryopreservation of yellowfin seabream (Acanthopagrus latus) spermatozoa (Teleost, Perciformes, Sparidae)

The effects of both osmolality and cation in the initiation of sperm motility were examined in yellowfin seabream, Acanthopagrus latus. Various factors involved in the cryopreservation of yellowfin seabream spermatozoa on motility are discussed. Extender containing only glucose proved to be a suitable medium for freezing yellowfin seabream spermatozoa to -196 degrees C. Glycerol seems to have a direct osmotic effect on yellowfin seabream sperm cells, and it induced sperm motility before freezing and during thawing. However, this exhausted the energy needed for sperm motility for fertilization. Dimethyl sulfoxide (DMSO) proved superior to ethylene glycerol, propylene glycerol, glycerol and methanol as a cryoprotectant. Prolonged equilibration time had a detrimental effect on both prefreezing and post-thawing sperm motility. The estimated optimum freezing rate was in the range of -20 to -154 degrees C/min. More frozen-thawed than fresh spermatozoa are required to achieve comparable fertilization rates.     

Stock discrimination and connectivity assessment of yellowfin seabream (Acanthopagrus latus) in northern South China Sea using otolith elemental fingerprints

Connectivity between fish stocks is fundamental to the understanding of population dynamics and the implementation of sustainable fisheries management. Otolith microchemistry is a promising tool as it can provide information on the continuous growth of otoliths and the environmental effects on otolith composition. Such elemental fingerprints can help distinguish different stocks or life history stages, identify the origins or nursery areas of fish, and assess population structure. In this study, we examined the stock discrimination and spatial connectivity of cage-cultured and wild stocks of yellowfin seabream (Acanthopagrus latus) from the coastal waters of Shantou, Yangjiang, and Zhanjiang in China southern province Guangdong during 2012–2014, based on otolith trace-elemental signatures using multivariate statistical analysis and machine learning approaches. The concentrations of 13 elements (⁷Li, ²³Na, ²⁴Mg, ⁴⁰Ca, ⁵⁵Mn, ⁵⁶Fe, ⁵⁹Co, ⁵⁹Ni, ⁶⁴Cu, ⁶⁵Zn, ⁸⁸Sr, ¹²²Sb, and ¹³⁷Ba) in the natal spot of fish otoliths, representing the embryonic and paralarval stages of fish, were analyzed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Stepwise discriminant analysis and random forests were used to distinguish the cultured and wild stocks of yellowfin seabream, and non-metric multidimensional scaling (NMDS) and cluster analysis were used to determine the spatial variation and connectivity of yellowfin seabream stocks. Overall, the cultured and wild stocks of yellowfin seabream could be identified with classification accuracy of 80.7% and 99.2% by using stepwise discriminant analysis and random forests respectively. When we compared site difference between cultured and wild stocks (site × stock interactions), the classification success was 60.4% for stepwise discriminant analysis and 85.7% for random forests. The misclassification of cultured and wild stocks within the three sites suggested the spatial connectivity between stocks and among sampling locations. Our findings suggested that the three wild stocks of yellowfin seabream from Guangdong coastal waters could be considered as one unit for management, and the difference between cultured and wild stocks was significant for yellowfin seabream from Shantou and Yangjiang, but less significant for yellowfin seabream from Zhanjiang. This study demonstrated that otolith elemental fingerprints can help improve our knowledge on the spatial connectivity, population structure, and life history of fish stocks, and random forests can be a useful tool for identifying cultured and wild stocks compared to the traditional stepwise discriminant analysis.     

四种鲷科鱼类的精子激活条件与其生态习性的关系

研究了盐度、ｐＨ和温度和对黄鳍鲷Ｓｐａｒｕｓ ｌａｔｕｓ（Ｈｏｕｔｔｕｙｎ）、平鲷Ｒｈａｂｄｏｓａｒｇｕｓ ｓａｒｂａ（Ｆｏｒｄｋａｌ）、黑鲷Ｓｐａｒｕｓ ｍａｃｒｏｃｅｐｈａｌｕｓ（Ｂａｓｉｌｅｗｓｋｙ）和真鲷ｐａｇｒｏｓｏｍｕｓ ｍａｊｏｒ（Ｔｅｍｍｉｎｃｋ ｅｔ Ｓｃｈｌｅｇｅｌ）４种鲷科鱼类精子活力的影响。比较了南海区４种鲷科鱼类精子对盐度、ｐＨ和温度和适应性探讨了４种鲷科鱼类的精子激活条     

Additional microsatellites for Sparus aurata and cross‐species amplification within the Sparidae family

Six new microsatellite loci were isolated and characterized in 32 individuals from a farm population of gilthead seabream (Sparus aurata). Expected heterozygosity at all loci was high, ranging from 0.835 to 0.958 with between 10 and 27 alleles per locus. A multiplex polymerase chain reaction protocol was developed using four of the loci. Cross‐species amplification of the loci was tested in six species of the Sparidae family and four loci were successfully amplified in two or more related species.     

Chromosome-level Genome Assembly of Acanthopagrus latus Provides Insights into Salinity Stress Adaptation of Sparidae

Marine Biotechnology - The yellowfin seabream, Acanthopagrus latus, is widely distributed throughout the Indo-West Pacific. This species, as a euryhaline Sparidae fish, inhabits in coastal...     

Plasma sex steroids and gonadosomatic index variations during ovarian development of female wild yellowfin seabream (Acanthopagrus latus)

The yellowfin seabream (Acanthopagrus latus) has a good potential for mariculture in Iran, so studies on various aspects of its culture has been carried out. In this study, the characteristic of reproduction in this species was investigated. The involvement of steroid hormones in the development of gonads was assayed by sampling blood and gonad tissue in 85 females of A. latus in fish caught from the Musa Creek, north-west Persian Gulf from October 2010 to May 2011. Gonadosomatic index (GSI) and hepatosomatic index (HSI) were recorded. Developmental stages were associated with changes in sex steroids, GSI and HSI. GSI and HSI began to increase in November (immature stage) and reached the highest value in March (ripe stage), decreasing sharply in April (spent stage). Plasma values of 17β-estradiol (E2) levels reached their highest levels in spawning females in March and then decreased in April. Progesterone levels were low through ovarian development, reached a maximum simultaneously with testosterone in February (mature stage) and then decreased in March (ripe stage). The seasonal changes observed in plasma steroid levels and GSI reflected the pattern of oocyte development and the spawning behavior of yellowfin seabream and were typical of the patterns described in most multiple spawners studied to date.     

Significant population genetic structure of yellowfin seabream Acanthopagrus latus in China

The yellowfin seabream Acanthopagrus latus is widely distributed throughout the Indo‐West Pacific. The genetic analyses of mtDNA control region sequence variation in samples from Chinese waters revealed a pattern of genetic structure between southern and northern samples (P < 0·05) and high levels of genetic diversity in this species. Significant isolation by distance between southern and northern locations (Mantel test r = 0·35, P = 0·04) and among northern populations (r = 0·55, P = 0·01) indicated that ocean straits and other barriers substantially limit gene flow. Phylogeographical analysis also revealed two major divergent mtDNA lineages across Chinese waters. For conservation, A. latus populations in Chinese waters should be divided into at least two management units for protection.     

Isolation and characterization of microsatellite markers for the heavily exploited rockfish Sebastes schlegeli, and cross-species amplification in four related Sebastes spp.

Here we report development and characterization of 14 polymorphic microsatellite loci from Sebastes schlegel. Polymorphism at these loci revealed from 3 to 23 alleles. The observed heterozygosity ranged from 0.34 to 1.00, and the expected heterozygosity ranged from 0.31 to 0.95. No linkage disequibrium was found. Two loci were significantly deviated from HWE (P < 0.01). The 14 loci were also surveyed in four other Sebastes species and 12 loci successfully amplified, where allelic diversity ranged from highly polymorphic to monomorphic. These results demonstrate these microsatellite markers can be used for the study of intra- and inter-specific genetic diversity.     

Digestive enzymes in marine species. II. Amylase activities in gut from seabream (Sparus aurata), turbot (Scophthalmus maximus) and redfish (Sebastes mentella)

The amylase activity of the digestive tract of three carnivorous fish species (Sparus aurata, Scophthalmus maximus and Sebastes mentella) has been studied. The activity of seabream and turbot showed its maximum at neutral pH (7.0–7.5); meanwhile, the activity of redfish had an optimum pH at 4.5-5.0. The t° function ranged between 35 and 45°C for the three species. The Arrhenius plots of the intestinal activities of seabream and turbot showed breakpoints at temperatures close to those of their physiological activities. High saline concentrations inhibited the activity of seabream and turbot and activated the activity of redfish. Seabream activity was absolutely dependent on calcium ions. On the contrary, redfish activity was only detected in the absence of this metal. Studies carried out by using several effectors suggested that the activities found in these three species are different. Considering our results from a point of view of the environmental conditions of these species, it might be concluded that enzymatic digestion of dietary carbohydrates proceeds at very low rate. Physiological implications are discussed.     

Direct Evidence for Mendelian Inheritance of the Variations in the Ribosomal Protein Gene Introns in Yellowfin Tuna (Thunnus albacares)

Restriction fragment length polymorphism found in the S7 ribosomal protein gene introns of yellowfin tuna (Thunnus albacares) was compared between a single pair of parents and their offspring. The sizes of the first intron (RP1) and second intron (RP2) amplified by polymerase chain reaction were 810 bp and 1400 bp, respectively. The dam and sire had different restriction types from one another in HhaI and RsaI digestions for RP1 and in DdeI, HhaI, and ScrFI digestions for RP2. Putative genotypes in both introns of 64 larvae were found to be segregated in Mendelian proportions. Genotype distributions in a wild yellowfin tuna sample (n= 34) were in Hardy-Weinberg proportions, and observed heterozygosity ranged from 0.149 to 0.388. This study presents novel Mendelian markers, which are feasible for tuna population genetic study and pedigree analysis. Received December 8, 1999; accepted April 11, 2000.     

Quantitative trait loci affecting morphology traits in gilthead seabream (Sparus aurata L.)

We report a quantitative trait loci (QTL) mapping study on 18 morphometric characters in gilthead seabream based on a total of 74 informative microsatellite markers genotyped in 409 offspring coming from 10 paternal half‐sib families. Statistical analysis was carried out using a linear regression approach, and various suggestive and significant morphology QTL were detected in three (9, 21 and 25) of nine linkage groups examined. Fitting body weight as a covariate reduced the significance of some QTL but revealed three new QTL in other linkage groups (LG6 and LG10). Current results combined with those obtained from previous studies underline highly significant loci affecting overall growth and morphology in S. aurata.     

Development of polymorphic EST-derived SSR markers for the shrimp, Fenneropenaeus chinensis

In our study, we evaluated simple sequence repeat (SSR) markers from expressed sequence tags (ESTs) of Fenneropenaeus chinensis. Characteristics of 11 EST-SSR loci were investigated using 34 F. chinensis individuals. The number of alleles per locus ranged from 4 to 9. The observed heterozygosity ranged from 0.118 to 0.826, while the expected heterozygosity ranged from 0.623 to 0.847. Two loci (T2 and T12) conformed to the Hardy–Weinberg equilibrium. There was no LD observed between all pairs of EST-SSRs loci. The PIC values of 11 microsatellite loci were higher than 0.5. These loci and markers will be useful for population genetics and systemic evolution of F. chinensis.     

Characterization of eight polymorphic microsatellite loci from the Bengalese finch (Lonchura striata var. domestica)

Eight polymorphic microsatellite loci were isolated and characterized from the Bengalese finch (Lonchura striata var. domestica). In analyses of 25 individuals, the number of alleles ranged from two to four, and observed heterozygosity ranged between 0.05 and 0.73. At four loci, the observed heterozygosity of the Bengalese finches was significantly different from the expected heterozygosity. Primer sets were also tested in Javan munia (Lonchura leucogastroides), and the same eight loci were successfully amplified. In analyses of 20 unrelated individuals, the number of alleles ranged from one to seven, and the observed heterozygosity ranged from 0 to 0.56. In Javan munia, the observed heterozygosity differed significantly from the expected heterozygosity in only one locus.     

Development and characterization of microsatellite loci for lotus (Nelumbo nucifera)

This paper reports the development of microsatellite primers for Nelumbo nucifera Gaerten. By screening genomic libraries enriched with 10 kinds of probes, Seventeen polymorphic loci were isolated and primers were designed. Polymorphism of these 17 loci was assessed in 24 individuals. All the 17 loci are polymorphic and the number of alleles ranged from two to seven. Observed heterozygosity and expected heterozygosity ranged from 0.0000 to 0.9176 and from 0.2837 to 0.7917 respectively. These microsatellite loci should be useful for studying the genetic diversity of N. nucifera.     

Isolation and characterization of 16 polymorphic microsatellite loci in the endemic Hawaiian damselfly Megalagrion xanthomelas (Odonata: Coenagrionidae)

Microsatellite loci have been isolated from two species of endemic Hawaiian damselflies, Megalagrion xanthomelas and M. eudytum, that are of conservation concern. Sixteen polymorphic loci were characterized in 32 M. xanthomelas from one population on Molokai and one on Hawaii Island. The total number of alleles per locus ranged from two to 16 and observed population heterozygosity ranged from 0.0 to 0.963. Eleven of these loci amplified successfully in M. eudytum as well. These loci will be used to further conservation efforts and infer genetic consequences of Pleistocene glaciations.     

Development and characterization of 13 novel microsatellite loci from the flat-headed bat (Tylonycteris pachypus) with cross-species amplification in closely related taxa

13 novel microsatellite loci was isolated using the enriched library method from genomic DNA of the flat-headed bat (Tylonycteris pachypus). These loci showed high levels of genetic polymorphism testing on 54 individuals sampled from Guangxi province, China. The number of observed alleles per locus ranged from 2 to 15. The expected and observed heterozygosity values ranged from 0.170 to 0.900 and from 0.185 to 0.944, respectively. One loci departed significantly from Hardy-Weinberg equilibrium (HWE) after Bonferroni correction and no Linkage disequilibrium was found between any pairs of loci. In addition, these loci were tested in the sister species, Tylonycteris robustula, seven loci amplified successfully and were also polymorphic.     

Fifteen polymorphic microsatellite loci from Jamaican streamertail hummingbirds (Trochilus)

We isolated and characterized 15 microsatellite loci from the endemic Jamaican streamertail hummingbird Trochilus polytmus. Loci were screened in 12 individuals of both T. polytmus and its sister species T. scitulus, also a Jamaican endemic. The number of alleles per locus ranged from 2 to 10, observed heterozygosity ranged from 0 to 1, and the probability of identity values ranged from 0.038 to 0.663. These new loci provide tools for characterizing the narrow hybrid zone between the two species.     

Isolation and characterization of polymorphic microsatellite loci in the field vole,Microtus agrestis,and their cross‐utility in the common vole,Microtus arvalis

We developed nine polymorphic microsatellite loci for the field vole, Microtus agrestis. The number of alleles ranged from five to 15 and observed heterozygosities ranged from 0.40 to 1.00. We also tested the microsatellite loci for amplification and polymorphism in the congeneric species Microtus arvalis. Five of the nine loci were successfully analysed in this species. The microsatellite markers will be employed in studies of reproductive success and fine‐scale spatial genetic structure.     

Development and characterization of twelve polymorphic microsatellite loci in the threatened Red Hills salamander, Phaeognathus hubrichti

We isolated and characterized 12 microsatellite loci from the endangered Red Hills salamander, Phaeognathus hubrichti. Loci were screened in 24 individuals of P. hubrichti. The number of alleles per locus ranged from 2 to 16, observed heterozygosity ranged from 0.130 to 0.750, and the probability of identity values ranged from 0.012 to 0.778. These new loci provide tools for examining the population genetics of this federally threatened salamander.