On the age and growth of flounder Paralichthys orbignyanus (Jenyns, 1842) in Bahía Blanca Estuary, Argentina

Estimates of age and growth of flounder Paralichthys orbignyanus (Jenyns,1842) were made by analysing fish from commercial catches in Bahía Blanca estuary (39° LS). A total of 823 fish caught by fishing fleets operating in the estuary were collected between February 1997 and January 1998. Age was determined via scale reading and growth estimation parameters using von Bertalanffys equation. Annulus formation occurred in August. The age for the total population, which ranged from 7.7 to 87.5 cm TL was 0–7. Age ranged from 0 to 6 years (21.5–71.9 cm TL) in males and from 0 to 7 years (24.9–87.5 cm TL) in females. Length–weight relationships were W(g)=0.0093 L(cm) exp. 3.03 for the total population, W(g)=0.0147 L(cm) exp. 2.91 for females, and W(g)=0.0168 L(cm) exp. 2.87 for males, respectively. As from age three, females were longer and heavier than males. The growth parameters estimated for the total population, for females and for males were L=83.29, 79.66, and 46.11 cm, respectively; k values were 0.18, 0.23, and 0.92, respectively, and t₀ values were –1.87; –1.54, and –0.62, respectively. Similarly to other flounders,P. orbignyanus is a typical inhabitant of estuaries and coastal regions. Adults stay in the study area mainly during spring and summer, they go outside or offshore during the spawning period and then they return to the estuary for feeding and recovering.     

Inheritance Characteristics of Microsatellite DNA Loci in Experimental Families of Japanese Flounder Paralichthys olivaceus

Allele segregating patterns of microsatellite DNA loci in 5 experimental families of Japanese flounder Paralichthys olivaceus and genotype frequencies for deviation from Hardy-Weinberg expectations (HWE) in natural P. olivaceus populations were studied to assess inheritability. Of the 12 microsatellite loci examined, 1 locus had a possibility of scoring errors of heterozygous individuals caused by unreproducible polymerase chain reaction amplifications of a particular allele. At the remaining 11 loci, almost all of alleles were segregated according to Mendelian transmission, and observed genotype frequencies in natural populations were consistent with HWE. The results demonstrated here would provide useful information supporting the suitability of these microsatellite loci as inheritable P. olivaceus genetic markers. Received September 25, 2000; accepted March 1, 2001     

A case of reversal in Paralichthys orbignyanus a shallow-water flounder from the south-western Atlantic

A right-sided Paralichthys orbignyanus was reported for the first time in the western South Atlantic. Some morphometric peculiarities were noticed in the reversed specimen compared with the normal flatfish of the same species.     

Parasitic nursing behavior in the wedge-capped capuchin monkey (Cebus olivaceus)

Juvenile and adult females in two wild groups of wedge-capped capuchin monkeys (Cebus olivaceus) were observed nursing from other adult females. The context of the interactions varied with participants but always involved a higher-ranking female nursing from a lower-ranking female. This behavior appears to be an example of an exploitative interaction in which the suckling female benefits at the expense of the nursing female.     

牙鲆IGF-IR 基因5＇调控区的克隆及功能初步分析

胰岛素样生长因子-I受体(Insulin-like growth factorI receptor,IGF-IR)是一种跨膜的酪氨酸激酶受体蛋白,是IGF-I生物功能的关键调节因子之一.当配体IGF-I与其结合时激活酪氨酸激酶活性,从而引起大多数细胞的促有丝分裂和抑制凋亡效应,在细胞的正常生长和分化中起至关重要的作用.在生物体内,IGF-IR基因的表达受到多层次的调控,其中以转录水平的调控为主.人IGF-IR基因的启动子是一个不含TATA框和CAAT框、高GC含量、"initiator"型的启动子.P53、SP1、KLF16、c-Jun、ER-α和WT1等均是入IGF-IR基因5调控区已鉴定的转录因子[1 4].但是在低等生物包括鱼类中,IGF-IR基因的5'调控区序列及启动子特征很少有报道.     

Extracellular ATP is a potent signaling molecule in the activation of the Japanese flounder (Paralichthys olivaceus) innate immune responses

Innate immunity is the first line of defense against pathogen infections. Extracellular ATP (eATP) is one of the most studied danger-associated molecular pattern molecules that can activate host innate immune responses through binding with and activating purinergic receptors on the plasma membrane. The detailed actions of eATP on fish innate immunity, however, remain poorly understood. In this study, we investigated bacterial pathogen-induced ATP release in head kidney cells of the Japanese flounder Paralichthys olivaceus. We also examined the actions of eATP on pro-inflammatory cytokine and immune-related gene expression, the activity of induced NO synthase (iNOS), and the production of reactive oxygen species (ROS) and NO in Japanese flounder immune cells. We demonstrate that ATP is dynamically released from Japanese flounder head kidney cells into the extracellular milieu during immune challenge by formalin-inactivated Edwardsiella tarda and Vibrio anguillarum. In addition, we show that eATP administration results in profound up-regulation of pro-inflammatory cytokine gene expression, iNOS activity, and inflammatory mediator production, including ROS and NO, in Japanese flounder immune cells. Altogether, our findings demonstrate that eATP is a potent signaling molecule for the activation of innate immune responses in fish.     

Sequences of 596 cDNA Clones (565,977 bp) of Japanese Flounder (Paralichthys olivaceus) Leukocytes Infected with Hirame Rhabdovirus

We have partially sequenced 785 sequences of 596 independent complementary DNA clones isolated from a cDNA library of Japanese flounder leukocytes infected with hirame rhabdovirus. These sequences consist of a total of 565,977 base pairs. The average size of the sequenced lengths was 721 bp. Of 596 clones, 386 (64.8%) were identified as previously reported genes by the BLASTN and BLASTX programs. About 30% of the identified clones could be recognized by only the BLASTX program. A total of 251 distinct genes were identified, and 181 of these genes are the first such genes reported from the teleostei. Approximately 27% of the identified Japanese flounder genes appear to be associated with cell division, cell structure or motility, and basic energy metabolism, 29% with gene or protein expression, and 17% with cell signaling, cell communication, and cell or organism defense. The most frequently identified expressed sequence tags of leukocytes of Japanese flounder were gelatinase b and ribosomal protein L23, which both had 1.34% prevalence. Received February 12, 1999; accepted April 13, 1999     

Density-dependent predation and implications for stock enhancement with Japanese flounder

In laboratory predation trials kinsen-gani crab Matuta lunaris rarely preyed on hatchery-reared (HR) Japanese flounder Paralichthys olivaceus , even at extremely elevated prey densities ( c . 90 fish m⁻²), but fed readily on sacrificed Japanese founder. This suggests that under similar conditions in the wild predator-prey interactions between kinsen-gani and juvenile Japanese flounder are likely to be weak. Larger Japanese flounder readily cannibalized smaller conspecifics, suggesting that within-release group cannibalism may contribute considerably to post-release mortality of HR Japanese flounder when sufficient size variation exists within groups of released fish. Kinsen-gani presence had no effect on within-release group cannibalism rates of large Japanese flounder on small Japanese flounder. Within-release group cannibalism rates were significantly affected by densities of smaller (prey) fish, implying that the number of fish released (and thus post-release densities) in stock enhancement programmes may significantly affect post-release mortality rates. The probability of within-release group cannibalism increased rapidly as the cannibal-to-prey size ratio exceeded 1.6, suggesting that minimizing size variation of released HR individuals will reduce post-release cannibalism rates. These results have implications for Japanese flounder stock enhancement release strategies, and may be applicable to other finfish stock enhancement programmes.