Zoological Science
Volume 26, Issue 4, 2009
Volumes & issues:
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Biochemistry
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A D-galactose-Binding Lectin with Mitogenic Activity from Musca domestica Pupae
View Description Hide DescriptionA lectin with potent mitogenic activity was isolated from Musca domestica pupae. The lectin was a monomer with a molecular weight of 55 kDa. The purification procedure mainly involved affinity chromatography on galactose-Sepharose-4B. The lectin agglutinated trypsin-treated rabbit blood cells. D-galactose was detected to inhibit the lectin's hemagglutination activity. The lectin was metal independent and temperature dependent and was detected by the periodic acid-Shiff reaction to be a glycoprotein with a carbohydrate content of 2.1%. Observations with an atomic force microscope indicated that the lectin was a globular protein about 75 nm in size, with several carbohydrate chains linked to it. It elicited a mitogenic response from mouse splenocytes in vitro, with the maximal response at a concentration of 20 µg/ml. No lectin has been reported before from Musca domestica pupae, and the lectin we discovered could be of great importance in insect immunity and hypoimmune diseases.
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Cell Biology
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Cell Growth-Promoting Activity of Fluid from Eye Sacs of the Bubble-Eye Goldfish (Carassius auraitus)
View Description Hide DescriptionThe growth-promoting effects of fish body fluids, such as serum and embryonic extract, on fish cell cultures have been widely demonstrated. The bubble-eye variety of aquarium goldfish is characterized as having a large sac filled with fluid (sac fluid) under each eye. These sacs are believed to contain lymph, which is similar in composition to serum or blood plasma. In order to test whether the sac fluid can be used as an additive for fetal bovine serum (FBS) in growth factor supplements, we compared cell growth in media containing FBS together with different concentrations of sac fluid. A dose-dependent growth-promotion effect was observed in early passage caudal fin cells from both medaka and zebrafish. Cell-growth promotion was also confirmed in early passage medaka blastula cells and in a zebrafish embryonic cell line (ZF4). Replacement of the fluid in the eye sacs of bubble-eyes occurs within a couple of months after the sac fluid has been harvested, and the cell-growth promoting activity of the new fluid is similar to that of the fluid that was tapped initially. These findings suggest that sac fluid can be used as a growth-promoting supplement for fish cell culture. Importantly, the ability of the goldfish to replace the fluid combined with the fact that equipotent fluid can be repeatedly harvested from the eye sacs means that a sustainable source of the fluid can be obtained without needing to sacrifice the fish.
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Developmental Biology
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The Presence of Chimeric DNA Consisting of 5' Regions of the Hemoglobin and Nucleosome Assembly Protein-1 Genes in Paramecium caudatum Macronuclear Genomic DNA
View Description Hide DescriptionWe detected an unexpected small-sized DNA fragment during polymerase chain reaction (PCR) analysis of the heterogeneity of a macronuclear intergenic region of Paramecium caudatum. Southern blotting of total genomic DNA with the PCR product as a probe indicated that the small-sized DNA fragment constituted part of the macronuclear genome. Sequencing revealed that the PCR product was a chimeric DNA structure that may be generated by tail-to-tail fusion of the 5' region of the hemoglobin (hb) gene to most of the nucleosome assembly protein-1 (nap-1) gene. Short tandem repeats consisting of tetra- and tri-nucleotides exist at the putative cleavage sites in the hb and nap-1 genes, respectively. This feature differs from those found at the boundaries of TA-internal eliminated sequences in the P. aurelia complex and at transposable elements in other species. This suggests that the chimeric DNA is generated by a novel mechanism. Although the chimeric DNA contains the hb and nap-1 promoters, transcripts corresponding to the chimeric DNA were not detected by reverse transcription (RT)-PCR analysis during vegetative cell growth. Possible roles of chimeric DNA are discussed.
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Diversity and Evolution
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Geographic Variation in Morphological Traits of the Large Japanese Field Mouse, Apodemus speciosus (Rodentia, Muridae), from the Izu Island Group, Japan
View Description Hide DescriptionWe investigated geographic variation in morphological traits of the large Japanese field mouse (Apodemus speciosus) from the Izu Island Group, Japan. There was sexual dimorphism in external characters and cranial measurements; hence, these were considered in subsequent analyses. There was geographic divergence in morphometric characters among populations of the Izu Island Group and Honshu. Mice from the Miyakejima Island and Niijima-Shikinejima Islands differed from those of other populations and from each other; Oshima Island mice also differed, but to a lesser degree. Mice from three populations from Honshu were similar to one another, and mice from Kozushima Island were more similar to those from Honshu populations than those from Izu Island Group populations. These results suggest that A. speciosus populations in the Izu Island Group may have had multiple origins. One possible hypothesis to explain these patterns of variation is that the Miyakejima, Niijima, and Shikinejima populations may share a relatively longer history of overseas dispersal, whereas the Kozushima populations may have experienced a recent invasion from Honshu via human activities.
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Endocrinology
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Increased Mass of Slow-Type Skeletal Muscles and Depressed Myostatin Gene Expression in Cold-Tolerant Chicks
View Description Hide DescriptionTemperature is maintained in birds by skeletal muscle shivering as well as by non-shivering thermogenesis in a cold environment because they lack brown adipose tissue, which is a mammalian thermogenic organ. Chicks acquire cold tolerance after their skeletal muscles mature. Here, we found that muscle fibers transformed to the slow-twitch type with increasing gene expression of peroxisome proliferator-activated receptor-γγ coactivator-1αα (PGC-1αα), and that the mass increased with decreasing myostatin gene expression, in the leg muscles of 7-day-old and younger chicks within 24 h of cold exposure. Muscle fibers did not transform and the mass did not increase within 24 h of cold exposure in muscles from chicks older than 8 days of age. Myostatin mRNA expression remained depressed in cold-tolerant muscles for 24 h, whereas cold-enhanced growth of the muscle continued for 48 h. Myostatin expression was depressed and muscle mass was increased only in chick leg muscles that comprised both fast- and slow-twitch fibers. These results suggest that the acute regulation of PGC-1ααa and myostatin gene expression in leg muscles is required for chicks to acquire cold tolerance up to 7 days of age.
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Molecular Biology
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Identification of a Cytoplasmic Manganese Superoxide Dismutase (cMnSOD) in the Red Swamp Crawfish, Procambarus clarkii: cDNA Cloning and Tissue Expression
View Description Hide DescriptionA cytoplasmic manganese superoxide dismutase (cMnSOD) cDNA was cloned from the hepatopancreas of the red swamp crawfish, Procambarus clarkii. An initial cDNA fragment was identified by using degenerate primers, and the complete sequence was obtained by using RACE methodology. The full sequence comprises 1140 bp, with an open reading frame of 858 bp encoding a protein of 286 amino acids. Sequence analysis showed that this protein is highly homologous to previously obtained crustacean cMnSODs. Phylogenetic analysis clusters it with all known cMnSODs and in a group distinct from mitochondrial MnSODs. cMnSOD transcripts were detected in the gills, tail muscle, green glands, and hepatopancreas. The data provide additional evidence for the hypothesis that cMnSOD replaced CuZnSOD in crustaceans that use haemocyanin as the respiratory pigment.
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Morphology
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Functional Morphology of Femoral Glands in the Tegu Lizard, Tupinambis merianae
View Description Hide DescriptionSeveral lizards have femoral glands, which have an influence in various reproductive behaviors. In this paper we describe the morphological organization of the femoral glands in the Tegu, Tupinambis merianae, by means of light and electron microscopy. Even though these glands are present in both genders, secretions during the reproductive period can only be found in males. The glandular parenchyma, which is organized in numerous secretory units, consists of keratinocyte-like cells and granular cells. The holocrine secretion is constituted from both cells, which lose their integrity and become a semi-amorphous material, reinforced by keratin sheets. The discharges of each unit merge together into a solid cylinder of secretion, surrounded by epithelial cells, that is extruded to the exterior. The keratin sheets and epithelial layers that surround both the complete and partial secretions form a sort of structural support suitable for the type of territorial demarcation characteristic of the species. The granular cells, supposedly the producers of pheromones, are characterized by the presence of electron-dense granules and multilaminar membranous bodies that show ultrastructural changes of unknown function. The free granules in the secretion cylinder may act as pheromone deposits.
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Reproductive Biology
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Two Distinct Localization Patterns of Testis-Specific Serine Protease 1 (TESSP1) in the Seminiferous Tubules of the Mouse Testis
View Description Hide DescriptionMouse Tessp1 has been shown to be a testis-specific gene that may contribute to spermatogenesis. In this report, we raised a specific antibody against TESSP1 to assess its biological role. Western blotting detected testicular TESSP1 in all postnatal developmental stages of the mouse. Experiments using the testes of W/Wv mice, which lack germ cells, indicated TESSP1 expression in Sertoli cells and Leydig cells. In immunofluorescence staining of the wild-type mouse testis, dot-like signals for TESSP1 were observed in the adluminal compartment of the seminiferous tubules, while diffused signals were found in the basal compartment. Generally, the dot-like and diffused signals overlapped with the trans-Golgi network marker RAB6 and the transmembrane protein CADHERIN 2, respectively. Some TESSP1 staining was also observed in association with interstitial Leydig cells of the testis. The results of this study suggest that TESSP1 is predominantly localized in the plasma membrane of spermatogonia and Sertoli cells in the basal compartment, but exhibits an intracellular localization, presumably in the Golgi apparatus, of spermatocytes and spermatids in the adluminal compartment of the seminiferous tubules. The expression of TESSP1 in both germ cells and somatic cells and alteration in its cellular localization in the germ cells during spermatogenesis indicate that it may have a unique role in the testis.
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Taxonomy
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Wing Geometric Morphometric Inferences on Species Delimitation and Intraspecific Divergent Units in the Merodon ruficornis Group (Diptera, Syrphidae) from the Balkan Peninsula
View Description Hide DescriptionA study of the Merodon taxa on the Balkan Peninsula, a region with a number of Pleistocene refugia, provides a useful framework for examining evolutionary processes and detecting hidden biodiversity. The phenotypic diversity of 22 samples of the Merodon ruficornis group on the Balkan Peninsula was examined using landmark-based geometric morphometrics. The boundaries of the species M. ruficornis, M. trebevicensis, M. auripes, M. armipes, and M. loewi were well defined based on wing shape and size. Canonical variate analysis showed that wing shape possessed sufficient differences to discriminate the species with a successful classification rate of 75–92% for males and 82–100% for females. The observed interspecific differentiation is generally in agreement with a previous study of the M. ruficornis group using a traditional morphological approach and molecular markers (allozyme loci, COI mtDNA). The spatial variability between conspecific populations and interpopulation variation were assessed based on both wing shape and size for male specimens. Phenotypically divergent units were delineated within previously defined species of the M. ruficornis group, indicating the possible presence of evolutionary independent units within the taxa analysed.
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Periophthalmus variabilis (Teleostei: Gobiidae: Oxudercinae), a Valid Species of Mudskipper, and a Re-diagnosis of Periophthalmus novemradiatus
View Description Hide DescriptionThe current concept of Periophthalmus novemradiatus (Hamilton, 1822) includes two species. Procurement of fresh material and examination of extant type specimens revealed that P. novemradiatus differs from P. variabilis Eggert, 1935, primarily in the number of anal fin rays (I, 12 or 13 vs. I, 10–12); the lateral scale series (62–67 vs. 48–60); the extent of fusion of the pelvic fins (56.0–90.0% vs. 32.0–48.8%); and the patterns of the first and second dorsal fins.
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