Morphological analysis of a deep-sea whelk <Emphasis Type="Italic">Buccinum tsubai</Emphasis> in the Sea of Japan

ABSTRACT:   Morphometrical analyses were performed on Buccinum tsubai , a deep-sea gastropod found in the Sea of Japan, and morphological differences were examined between the gender and among the four local subpopulations of Hokkaido, Yamagata-Toyama, the Yamato Bank, and San'in which are distinguished by mitochondrial DNA sequence analysis. As a result, sexual dimorphism of B. tsubai was found. Morphological differences were also recognized among four areas which may be related to genetic differences. They are also thought to be associated with the phenotypic plasticity in response to different environmental factors in each area. B. tsubai inhabits the the upper portion of the Sea of Japan Proper Water (UJSPW); and in the UJSPW of the Yamato Basin, nutrients are comparatively abundant and the dissolved oxygen content is low. Such environmental differences may be related to morphological differences among the four areas.     

Expression of taurine transporter in response to hypo-osmotic stress in the mantle of Mediterranean blue mussel

Expression of taurine transporter in response to osmotic stress was investigated at the protein level in the mantle of the Mediterranean blue mussel by using the specific antibody raised against the carboxy-terminal region of the deduced amino acid sequence of mussel taurine transporter. Immunohistochemical observation revealed that taurine transporter was expressed in the mantle and the expression was up-regulated in response to hypo-osmotic stress, while down-regulated in response to hyper-osmotic stress. Western blot analysis revealed major protein bands corresponding to 62 kDa and 65 kDa. In response to hypo-osmotic stress, the 62 kDa band became more intense, while it became less intense when the ambient osmolality was elevated. These results suggested that the 62 kDa taurine transporter would be implicated in hypo-osmotic adaptation.     

Difference in mass concentration of airborne dust during circular sawing of five wood-based materials

The object of this study was to compare the mass concentration of airborne dust during circular sawing of five wood-based materials: solid sugi (Cryptomeria japonica) lumber, tropical hardwood plywood, softwood plywood, particleboard, and medium-density fiberboard. Specimens were sawn at a constant feed per tooth (0.05 mm) using two saw speeds. The mass concentration of airborne dust of diameter 7.07 μm or less (respirable dust) was measured with a light-scattering dust monitor. The mass concentration showed a log-normal distribution, and the geometric means of mass concentration at saw speeds of 2000 and 3000 rpm were 2.33 and 2.89 mg/m³ for tropical hardwood plywood, 1.13 and 2.84 mg/m³ for particleboard, 0.91 and 2.28 mg/m³ for medium-density fiberboard, 1.09 and 1.38 mg/m³ for softwood plywood, and 0.32 and 0.66 mg/m³ for sugi lumber. The mass concentration for all five wood-based materials increased with the revolution speed of the circular saw.     

The Dnmt3b splice variant is specifically expressed in in vitro-manipulated blastocysts and their derivative ES cells

Manipulation of preimplantation embryos in vitro, such as in vitro fertilization (IVF), in vitro culture (IVC), intracytoplasmic sperm injection (ICSI), somatic cell nuclear transfer (SCNT) and other assisted reproduction technologies (ART), has contributed to the development of infertility treatment and new animal reproduction methods. However, such embryos often exhibit abnormal DNA methylation patterns in imprinted genes and centromeric satellite repeats. These DNA methylation patterns are established and maintained by three DNA methyltransferases: Dnmt1, Dnmt3a and Dnmt3b. Dnmt3b is responsible for the creation of methylation patterns during the early stage of embryogenesis and consists of many alternative splice variants that affect methylation activity; nevertheless, the roles of these variants have not yet been identified. In this study, we found an alternatively spliced variant of Dnmt3b lacking exon 6 (Dnmt3bΔ6) that is specific to mouse IVC embryos. Dnmt3bΔ6 also showed prominent expression in embryonic stem (ES) cells derived from in vitro manipulated embryos. Interestingly, IVC blastocysts were hypomethylated in centromeric satellite repeat regions that could be susceptible to methylation by Dnmt3b. In vitro methylation activity assays showed that Dnmt3bΔ6 had lower activity than normal Dnmt3b. Our findings suggest that Dnmt3bΔ6 could induce a hypomethylation status especially in in vitro manipulated embryos.     

Genetic population structure of the deep-sea whelk Buccinum tsubai in the Japan Sea

ABSTRACT:   The purpose of the present paper was to examine the genetic population structure of Buccinum tsubai in the Japan Sea. Mitochondrial 16SrRNA gene sequence analysis was performed with specimens from various stations in the Japan Sea. Mitochondrial lineages were clearly patterned geographically in four separate areas: the Hokkaido area, the Yamagata–Toyama area, the Yamato Bank area, and the San'in area. The main distribution depth range of B. tsubai is between 200 m and 1000 m isodepths, and the horizontal distance between the 200 m and 1000 m isodepth lines represents the specific spatial scale of the habitat (SSSH). These four areas were separated either by the complete discontinuity of the SSSH area or by its narrow spatial extension. Genetic distances between the main haplotypes of each area were calculated as Jukes–Cantor distances, the value of which ranged between 0.012 and 0.017. This value seemed to be unrelated to the geographic distance. There was no tendency for clustering according to depth. In future, the morphological characters of the four lineages of B. tsubai should be compared in detail in order to elucidate significant genetic differences among them.     

A new pyrethroid-type ester with strong knockdown activity

Thirteen pyrethroid-type esters of substituted 1(or 3)-hydroxymethylimidazolidine-2, 4-dione were synthesised and their knockdown activities against houseflies, mosquitoes and cockroaches were examined. Knockdown activities of 2,4-dioxo-1-prop-2-ynylimidazolidin-3-ylmethyl esters in oil solutions were higher than those of known knockdown pyrethroids; three of the compounds also possessed strong knockdown and flushing-out activities against cockroaches.     

Superoxide dismutase and catalase activities in the seminal plasma of normozoospermic and asthenozoospermic Beagles

We measured the blood plasma testosterone (T) levels and superoxide dismutase (SOD) and catalase activities in the seminal plasma of the ejaculates of 5 normal (2-5 years old) and 5 asthenozoospermic (AZ-) (3-5 years old) Beagles. Sperm ejaculated by AZ-dogs was incubated for 3 hr in Eagle's MEM only (controls) or Eagle's MEM containing 100 units/ml of SOD or catalase. Sperm motility was examined during incubation. The mean (+/- SE) plasma T level of the AZ-dogs (1.2 +/- 0.2 ng/ml) was significantly lower than in the normal dogs (2.5 +/- 0.2 ng/ml) (P<0.005). The mean (+/- SE) seminal plasma SOD and catalase activities (18.8 +/- 1.9 and 0.5 +/- 0.1 unit/g protein, respectively) were significantly lower in the AZ-dogs than in the normal dog (43.3 +/- 2.5 and 2.2 +/- 0.4 unit/g protein, respectively) (P<0.001 and 0.01, respectively). The motility of sperm incubated in Eagle's MEM containing SOD or catalase was significantly higher than that of control sperm incubated in only Eagle's MEM after 2 or 3 hr of incubation (P<0.05). The results of this study indicate that poor T secretion by the testes and low antioxidant enzyme activities are related to AZ in the dog.     

A "possible" involvement of TNF-alpha in apoptosis induction in peripheral blood lymphocytes of cats with feline infectious peritonitis

Feline infectious peritonitis (FIP) cats show a decrease in peripheral blood lymphocyte counts, and a particularly marked decrease in T cells including CD4+ and CD8+ cells. In this study, we showed that lymphopenia observed in FIP cats was due to apoptosis, and that the ascitic fluid, plasma, and culture supernatant of peritoneal exudate cells (adherent cells with macrophage morphology, or PEC) from FIP cats readily induced apoptosis in specific pathogen-free cat peripheral blood mononuclear cells, particularly CD8+ cells. In addition, TNF-alpha released from macrophages and TNF-receptor (TNFR) 1 and TNFR2 mRNA expression in lymphocytes were closely involved in this apoptosis induction. In particular, in CD8+ cells cultured in the presence of the PEC culture supernatant, the expression levels of TNFR1 and TNFR2 mRNA were increased, indicating that CD8+ cells are more susceptible to apoptosis induction by TNF-alpha than other lymphocyte subsets, particularly B cells (CD21+ cells). The results of this study suggest that TNF-alpha, produced by virus-infected macrophages, is responsible for induction of apoptosis in uninfected T cells, primarily CD8+ T cells.     

Developmental competence of cat oocytes from ovaries stored at various temperature for 24 h

We conducted two experiments to investigate the effects of storage temperature and period for cat ovaries on the meiotic and developmental competence of oocytes collected from the ovaries. In Experiment 1, ovaries were stored in physiological saline for 24 h at 4 C, 23-25 C, or 38 C (cold, room, and incubator temperature groups, respectively), and then oocytes were collected from the ovaries in each group. Morphologically intact oocytes were then selected and cultured in maturation medium for 24 h. Significantly more oocytes reached metaphase II (MII) in the cold temperature group (53.4%) than in the room and incubator temperature groups (20.0 and 2.4%, respectively). In Experiment 2, ovaries were stored in physiological saline at room temperature for 0, 6, 12 or 18 h, and then they were stored at 4 C (cold storage) until reaching a total storage period of 24 h. After storage of the ovaries, morphologically intact oocytes were matured, fertilized with frozen-thawed spermatozoa, and cultured in vitro. The rates of morphologically intact oocytes obtained from the ovaries stored at room temperature for 0, 6, 12 or 18 h were 35.3, 30.0, 26.4 and 14.7%, respectively, and the rates of intact oocytes that reached MII were 63.2, 36.4, 26.5 and 11.9%, respectively. The results suggested that the numbers of morphologically intact oocytes and intact oocytes that reached MII after in vitro maturation decrease gradually as the period of storage at room temperature before cold storage increases. Only oocytes from ovaries stored for 6 h developed to the blastocyst stage after in vitro maturation and fertilization when ovaries were stored at room temperature before cold storage. These results indicate that 24 h storage of ovaries at high temperatures (>23 C) decreases the meiotic competence of oocytes. The quality and developmental competence of oocytes are influenced by the length of storage at room temperature before cold storage.     

Melatonin protects the integrity of granulosa cells by reducing oxidative stress in nuclei,mitochondria, and plasma membranes in mice

Melatonin protects luteinized granulosa cells (GCs) from oxidative stress in the follicle during ovulation. However, it is unclear in which cellular components (e.g., nuclei, mitochondria, or plasma membranes) melatonin works as an antioxidant. GCs from immature (3 wks) ICR mice were incubated with hydrogen peroxide (H2O2; 0.01, 0.1, 1, 10 mM) in the presence or absence of melatonin (100 μg/ml) for 2 h. DNA damage was assessed by fluorescence-based immunocytochemistry using specific antibodies for 8-hydroxydeoxyguanosine (8-OHdG), an indicator of oxidative guanine base damage in DNA, and for histone H2AX phosphorylation (γH2AX), a marker of double-strand breaks of DNA. Mitochondrial function was assessed by the fluorescence intensity of MitoTracker Red probes, which diffuse across the membrane and accumulate in mitochondria with active membrane potentials. Lipid peroxidation of plasma membranes was analyzed by measuring hexanoyl-lysine (HEL), a oxidative stress marker for lipid peroxidation. Apoptosis of GCs was assessed by nuclear fragmentation using DAPI staining, and apoptotic activities were evaluated by caspase-3/7 activities. H2O2 treatment significantly increased the fluorescence intensities of 8-OHdG and γH2AX, reduced the intensity of MitoTracker Red in the mitochondria, increased HEL concentrations in GCs, and enhanced the number of apoptotic cells and caspase-3/7 activities. All these changes were significantly decreased by melatonin treatment. Melatonin reduced oxidative stress-induced DNA damage, mitochondrial dysfunction, lipid peroxidation, and apoptosis in GCs, suggesting that melatonin protects GCs by reducing oxidative stress of cellular components including nuclei, mitochondria, and plasma membranes. Melatonin helps to maintain the integrity of GCs as an antioxidant in the preovulatory follicle.