Embryonic development of the bullseye puffer Sphoeroides annulatus (Tetraodontidae): A morphofunctional approach to ontogenetic steps

The embryonic development of the bullseye puffer, Sphoeroides annulatus, was characterized on the basis of the theory of saltatory ontogeny. This theory predicts a correlative relationship between the ontogeny-type in an altricial-precocial spectrum and the habitat that a species occupies within an unstable-stable environmental spectrum. Because S. annulatus inhabits a variety of unstable environments along a wide latitudinal range, the hypothesis that this species presents one of the most altricial embryonic developments among tetraodontids was tested. Based on major developmental events that marked the ontogenetic thresholds nine embryonic steps were identified. Developmental features such as small adhesives eggs, lack of vitelline circulation, small free embryos swimming up at hatching guided by positive phototaxis, and small first-feeding larvae actively swam in the water column, suggest that S. annulatus belongs to the reproductive guild of the nonguarders-lithopelagophils. Moreover, a comparative analysis of the developmental sequences, egg size, and first-feeding larvae size between tetraodontids confirms the hypothesis of this study and supports the evolutionary principle of the altricial-precocial spectrum postulated in the theory of saltatory ontogeny.     

Patterns of occurrence of the platyhelminth parasites of the wild bullseye puffer (Sphoeroides annulatus) off Sinaloa, Mexico

This study provides basic information on the occurrence of platyhelminths in the wild bullseye puffer (Sphoeroides annulatus) from Sinaloa, Mexico. Specimens of pufferfish were collected from 2 localities: Teacapan (n = 161) and Mazatlan (n = 66). Six species of platyhelminths were recorded: 2 monogeneans (Diclidophoridae: Heterobothrium ecuadori and Capsalidae: Neobenedenia melleni) and 4 digeneans (Apocreadiidae: Homalometron longisinosum, Lepocreadiidae: Bianium plicitum, Gorgoridae: Phyllodristomum mirandai, and Fellodistomidae: Lintonium vibex). This is the first record of the platyhelminth L. vibex in S. annulatus in the Mexican Pacific. Bianium plicitum was the most abundant species, and H. ecuadori was the most prevalent species. The fish from Teacapan had the higher prevalence of platyhelminths. Teacapan had higher specific richness index, whereas Mazatlan had a higher dominance, 3.098 (Teacapan = 2.38). A relative risk analysis showed that B. plicitum was more likely to be present on fish in water within the temperature range of 21-25 C and from Teacapan compared with fish from the warmer water (26-30 C) or from Mazatlan. Heterobothrium ecuadori was more likely to be present at water temperatures of 23-24.5 C on fish from Teacapan and when other ectoparasites were present. Neobenedenia melleni also was more likely to be present when other parasites were present.     

Effect of LHRHa on the expression of stress‐related molecules in the ovary of wild caught Sphoeroides annulatus held in captivity

Two cDNA fragments corresponding to a heat shock protein and a cell death receptor were isolated from the ovary of the bullseye puffer Sphoeroides annulatus that were arrested in vitellogenesis or induced to ovulate with LHRHa. A reduced expression of both genes was observed following injections of LHRHa, suggesting these genes may participate in processes associated with the arrested ovarian development and preparation for atresia or ovulation.     

Presence of the Guinean puffer Sphoeroides marmoratus (Lowe, 1838) in the Mediterranean Sea

The collection of a single specimen of the Guinean puffer Sphoeroides marmoratus from the Ionian Sea in September 1977, misidentified at that time as Lagocephalus lagocephalus , shows that this subtropical species of fish has occurred in the Mediterranean Sea from 30 years ago.     

Huffmanela mexicana n. sp. (Nematoda: Trichosomoididae) from the marine fish Sphoeroides annulatus in Mexico

A new species of trichosomoidid nematodes, Huffmanela mexicana n. sp., is established on the basis of its egg morphology and biological characters. The dark-shelled, embryonated eggs of this histozoic parasite occur in masses in the inner layer of the swimbladder wall of the bullseye puffer fish Sphoeroides annulatus Jenyns, 1843 (Tetraodontidae, Tetraodontiformes) off the Pacific coast of Mexico (Sinaloa State) and are characterized mainly by their shape and size (63-69 x 30-33 microm), an aspinose surface, relatively small polar plugs, and their thick egg wall (4-5 microm). A key to Huffmanela species based on egg morphology is presented.     

The cloning of cyclin B3 and its gene expression during hormonally induced spermatogenesis in the teleost, Anguilla japonica

We cloned cyclin B1, B2, and B3 cDNAs from the eel testis. Northern blot analysis indicated that these cyclin B mRNAs were expressed and increased from day 3 onward after the hormonal induction of spermatogenesis, and that cyclin B3 was most dominantly expressed during spermatogenesis. In situ hybridization showed that cyclin B1 and B2 were present from the spermatogonium stage to the spermatocyte stage. On the other hand, cyclin B3 mRNA was present only in spermatogonia. Although mouse cyclin B3 is expressed specifically in the early meiotic prophase, these results indicate that eel cyclin B3 expression is limited during spermatogenesis to spermatogonia, but is not present in spermatocytes. These facts together suggest that eel cyclin B3 is specifically involved in spermatogonial proliferation (mitosis), but not in meiosis.     

Molecular cloning, gene localization, and structure of human cyclin B3

Here we describe the molecular cloning of human cyclin B3, its localization, and its structure. It is localized in the subcentromeric region of the X chromosome, still not completely sequenced by the Human Genome Project. This cyclin B3 is unusually large for a mitotic cyclin. Its mRNAs were found in all tissues and were particularly abundant in testis. At least three splice variants were found in the ORF and three variants in the 5'UTR.     

Reproductive cycle and sexual maturity of Sphoeroides annulatus (Jenyns, 1842) (Tetraodontiformes,Tetraodontidae) from the coast of Mazatlan,Sinaloa, Mexico

The reproduction of any fish species may be influenced by environmental factors, knowledge of which is required for an adequate control of the reproductive process to improve culture practices. Thus, the reproduction of a wild population of bullseye puffer, Sphoeroides annulatus (Jenyns, 1842), and the influence of temperature, photoperiod, lunar cycle and tide level were analyzed. Ovarian ripeness is asynchronous, and the ovary may ripen again at least once following spawning. Testes also display an asynchronous ripeness, but once sexual maturity is attained, spermatozoa are continually produced and released. The reproduction is highly seasonal, with an intense spawning period during the spring‐summer, when the sea surface temperature is 22.5–30.9°C and a 11–14 h photoperiod. The observations suggest that the timing of spawning is synchronized by a semi‐lunar cycle together with the rise of the average tide level. Size at first maturation was similar for females (28.2 cm TL) and males (28.6 cm TL). However, some specimens may start their gonad maturation when are as small as 19 cm TL.     

Consequences of experimental cortisol manipulations on the thermal biology of the checkered puffer (Sphoeroides testudineus) in laboratory and field environments

Anthropogenic climate change is altering temperature regimes for coastal marine fishes. However, given that temperature changes will not occur in isolation of other stressors, it is necessary to explore the potential consequences of stress on the thermal tolerances and preferences of tropical marine fish in order to understand the thresholds for survival, and predict the associated coastal ecological consequences. In this study, we used exogenous cortisol injections to investigate the effects of a thermal challenge on checkered puffers (Sphoeroides testudineus) as a secondary stressor. There were no significant differences between control and cortisol-treated fish 48 h following cortisol treatment for swimming ability (using a chase to exhaustion protocol), blood glucose concentrations or standard metabolic rate. In the lab, control and cortisol-treated puffers were exposed to ambient (29.1±1.5 °C), ambient +5 °C (heat shock) and ambient −5 °C (cold shock) for 4 h and to evaluate the consequences of abrupt temperature change on puff performance and blood physiology. Following cold shock, control fish exhibited increases in cortisol levels and weak ‘puff’ performance. Conversely, fish dosed with cortisol exhibited consistently high cortisol levels independent of thermal treatment, although there was a trend for an attenuated cortisol response in the cortisol-treated fish to the cold shock treatment. A 20-day complementary field study conducted in the puffer’s natural habitat, a tidal creek in Eleuthera, The Bahamas, revealed that cortisol-injected fish selected significantly cooler temperatures, measured using accumulated thermal units, when compared to controls. These results, and particularly the discrepancies between consequences documented in the laboratory and the ecological trends observed in the field, highlight the need to establish the link between laboratory and field data to successfully develop management policies and conservation initiatives with regards to anthropogenic climate change.     

In vivo expression and genomic organization of the mouse cyclin I gene (Ccni)

Cyclins control cell-cycle progression by regulating the activity of cyclin-dependent kinases. Cyclin I was recently added to the cyclin family of proteins because of the presence of a cyclin box motif in the deduced amino-acid sequence. Cyclin I may share functional roles with cyclin G1 and G2 because of the high structural similarity between their deduced amino-acid sequences. However, the biological and functional roles of this subclass of cyclins remain obscure. The mouse cyclin G1 and G2 genes have previously been cloned and characterized. In this report, we describe the cloning of the mouse homolog of cyclin I. The cyclin I cDNA sequence was used to determine the genomic organization of the mouse cyclin I gene which co-localizes with cyclin G2 to chromosome 5E3.3-F1.3. Cyclin I was transcribed from seven exons distributed over more than 19kb of genomic sequence. The expression of cyclin I was determined in various tissues, but no clear correlation with the proliferative state was found. Furthermore, in contrast to cyclin G1, cyclin I expression was stable during cell-cycle progression after partial hepatectomy in both the absence and presence of DNA damage. Transient expression of cyclin I-green fluorescent protein (GFP) fusion proteins in cell lines showed that cyclin I was distributed throughout the cell in contrast with the mainly cytoplasmic localization of cyclin G2 and nuclear localization of cyclin G1. Our results indicate that despite the close structural similarity between cyclin G1, G2 and I, these three proteins are likely to have distinct biological roles.     

兔精子发生过程中cyclin B1基因表达和蛋白定位的发育阶段依赖性

利用原位杂交和免疫组化等方法,研究兔精子发生过程中生精细胞cyclin B1 mRNA的表达和蛋白定位特点,结果显示,兔生精上皮中Cyclin B1 mRNA的主要分布在初级精母细胞中,直至圆形精子细胞仍然存在,于精子细胞的变态过程中逐渐消失,在伸长的精子细胞和精子中未检测出cyclin B1 mRNA,Cyclin B1蛋白在进入分裂期的精原细胞和精母细胞中表达,在圆形精子细胞和伸长的精子细胞中呈现大量的cyclin B1蛋白,上述结果表明,在兔精子发生过程中,cyclin B1 mRNA表达和蛋白定位具有发育阶段依赖性的特征。     

Molecular cloning and chimerisation of an inhibitory anti-cathepsin B antibody and its expression in Chinese hamster ovary cells

The lysosomal cysteine protease cathepsin B is one of several proteases that have been linked to tumour progression. Its increased expression and secretion in tumour cells may facilitate the degradation of extracellular matrix proteins, leading to tumour cell invasion and metastasis. Specific inhibitory monoclonal antibodies are a possible alternative to synthetic inhibitors as a therapeutic tool for cancer treatment. An inhibitory monoclonal antibody, which binds to an epitope near the active site of cathepsin B and inhibits its proteolytic activity, was prepared and its effect on invasion of ras-transformed MCF-10A neoT cells was tested in vitro. Here we present the nucleotide sequences of the heavy and light chains of the inhibitory antibody and compare them to the murine immunoglobulin germline sequences for possible somatic hypermutations. Since no harmful mutations were found, a mouse/human chimeric antibody was constructed by fusing murine V(H) and V(L) variable regions of the inhibitory antibody with human gamma 1 and K constant regions, respectively. Chinese hamster ovary K1 cells were co-transfected with expression vectors pcD-NA3L and pcDNA3H and the reactivity of the isolated chimeric antibody was tested by ELISA and Western blotting. We could demonstrate an inhibitory effect of the chimeric antibody.