Do tiny males grow up? Sperm competition and optimal resource allocation schedule of dwarf males of barnacles

Barnacles, marine crustaceans, have three sexual patterns: simultaneous hermaphroditism, dioecy and androdioecy. In dioecy and androdioecy, large individuals (females and hermaphrodites, respectively) are attached by dwarf males. Depending on species, some dwarf males grow up, others do not in their life time. To investigate which environmental conditions affect growth patterns of dwarf males of barnacles, we investigate the evolutionarily stable life history strategy of dwarf males using Pontryagin's maximum principle. Sperm competition among dwarf males and that among dwarf males and large hermaphrodites is taken into account. Dwarf males grow up in food-rich environments, while they do not grow at all in food-poor environments. ESS of the resource allocation schedule between reproduction and growth follows an "intermediate growth strategy" (simultaneous growth and reproduction) for dioecious species, in which sperm competition is not severe. On the other hand, it approaches "bang-bang control" (switching from allocating all resources toward growth then to reproduction), as sperm competition against surrounding large hermaphrodites becomes severe in androdioecious species.     

Characterization of the water quality of dam lakes on Shikoku Island, Japan

This study clarifies the distribution and variation of bioelements in dam lakes of the Shikoku region, Japan. The survey was carried out from 2002 to 2003 on three dam lakes in the Shikoku Mountains with high precipitation levels and on three dam lakes in the Sanuki mountain range with low precipitation levels. By the conventional classification for eutrophication, the dam lakes in the Shikoku Mountains were classified as oligotrophic to mesotrophic, whereas those in the Sanuki mountain range were classified as mesotrophic to eutrophic. Furthermore, for the dam lakes in the Sanuki mountain range, it was indicated that the amount of precipitation directly and indirectly affected lake water quality, such as high nitrogen concentration, low dissolved oxygen concentration, and increase in primary production. Especially, in a hypertrophic dam lake, during the period of low precipitation the surface water flowed out and the water under the thermocline, with no dissolved oxygen, appeared on the lake surface. As a result, the anaerobic environment extended across all the layers. Because a compulsory water-level operation was carried out in the dam lake, it was considered that the effect of the hydrological environment in the catchment area on the dam lake was relatively large in comparison with that in natural lakes.     

Porcine SPDYA2 (RINGO A2) stimulates CDC2 activity and accelerates meiotic maturation of porcine oocytes

RINGO, a protein with no homology to cyclin B, has been reported to be involved in activation of CDC2 and regulation of meiotic maturation in Xenopus oocytes. Although the presence of homologues of RINGO families, which are known as SPDY families, has been reported in mammals, their roles in meiotic maturation of mammalian oocytes have never been examined. In the present study, the effects of SPDY on meiotic maturation of porcine oocytes were examined. At first, Xenopus RINGO (xRINGO) mRNA was injected into immature porcine oocytes and found to significantly accelerate CDC2 activation and meiotic resumption. The CCNB (also known as cyclin B) synthesis was prematurely started at 12 h of culture, whereas it started at 18 h in normal oocytes. We next cloned RINGO A2 homologue in pig (pigSPDYA2) from total RNA of immature porcine oocytes by RT-PCR and obtained full-length cDNA that was more than 85% and 40% homologous with mammalian SPDYA2 and xRINGO, respectively. Acceleration effects similar to those by xRINGO were observed in CDC2 activation, meiotic resumption, and the start of CCNB synthesis in pigSPDYA2 mRNA-injected porcine oocytes. In clear contrast with the effects of xRINGO, which was accumulated abnormally in porcine oocytes and arrested them in the first meiotic metaphase (M1), pigSPDYA2 accelerated the meiotic progression, with about half of pigSPDYA2 mRNA-injected oocytes completing meiotic maturation within 30 h. These results suggest that pigSPDYA2 has important roles on meiotic maturation of porcine oocytes and that the rapid degradation of SPDY was necessary for the normal maturation of oocytes.     

The critical period for thyroid hormone responsiveness through thyroid hormone receptor isoform alpha in the postnatal small intestine

During second and third weeks after birth in rats, serum thyroid hormone level is elevated. In this study, we investigated the jejunal expression of thyroid hormone receptor (TR) alpha in developing rats. The TRalpha-1 mRNA level and TRalpha-1/TRalpha-2 mRNA ratio increased two-fold from 5 to 13 days after birth. This high level of TRalpha-1 mRNA was maintained until 20 days and then decreased to the basal level by the end of weaning period at 27 days; however, the level of TRalpha-2 mRNA remained unchanged throughout the developmental period. The increase in the TRalpha-1/TRalpha-2 mRNA ratio from 5 to 13 days was accompanied by an initial rise in the levels of mRNA for hexose transporters in the jejunum. Administration of T(3) during the suckling period (8-13 days) caused a 50% increase in the TRalpha-1/TRalpha-2 mRNA ratio, while administration of T(3) on days 12-17 and days 16-21, but not on days 22-27, caused a two to four-fold increase in the levels of mRNA for hexose transporters. These results suggest that a transient variation in the TRalpha-1/TRalpha-2 expression ratio is closely related to the critical period of thyroid hormone responsiveness for hexose transporters expression in the developing rat jejunum.     

Immunohistochemical and Biochemical Analyses of LGI3 in Monkey Brain: LGI3 Accumulates in Aged Monkey Brains

Leucine-rich glioma inactivated (LGI) 3 encodes a leucine-rich repeat protein. The precise function of LGI3, however, remains unknown. We have previously shown that amyloid-β peptide (Aβ) upregulates LGI3 and that Aβ and LGI3 colocalize on plasma membranes of cultured rat astrocytes. In the present study, we performed immunohistochemical and biochemical analyses of LGI3 using various aged monkey brains. Immunohistochemistry showed that LGI3 was present in almost all neural cells and mainly localized at plasma membranes and nuclei. In aged monkey brains, we found that LGI3 accumulated on or near the plasma membranes of neurons, and colocalized with endocytosis-associated proteins and lipid raft markers. Double immunohistochemistry also showed that LGI3 colocalized with Aβ in astrocytes of aged brains. Moreover, Western blot analyses revealed that LGI3 may be cleaved in brain. Additionally, in aged monkeys LGI3 accumulated in microsomal and nuclear brain fractions.     

Overexpression of VDUP1 mRNA sensitizes HeLa cells to paraquat

5-Bromodeoxyuridine (BrdU) induces or suppresses senescence-associated genes in any types of mammalian cells. From a cDNA library upregulated by BrdU in HeLa cells, we identified the gene encoding VDUP1 as a senescence-associated gene in normal human fibroblasts. To address a role of VDUP1 in senescence, we established HeLa cell clones, V7 and V27, which express its mRNA in a doxycycline-dependent manner. Although their growth in liquid culture was moderately retarded, colony formation on semi-solid medium was strongly inhibited by overexpression of the mRNA. We also examined susceptibility of these clones to various reagents. Consequently, colony formation in liquid culture was strongly inhibited by paraquat in these clones. Their superoxide dismutase activity was normal.     

Evaluation of Stem Cell-to-Tenocyte Differentiation By Atomic Force Microscopy to Measure Cellular Elastic Moduli

In the present study, we evaluated whether stem cell-to-tenocyte differentiation could be evaluated via measurement of the mechanical properties of the cell. We used mechanical uniaxial cyclic stretching to induce the differentiation of human bone marrow mesenchymal stem cells into tenocytes. The cells were subjected to cyclic elongation of 10 or 15 % at a cyclic frequency of 1 Hz for 24 or 48 h, and differentiation was assessed by real-time PCR (rtPCR) determination of messenger RNA expression levels for four commonly used markers of stem cell-to-tenocyte differentiation: type I collagen, type III collagen, tenascin-C, and scleraxis. The rtPCR results showed that cells subjected to 10 % cyclic elongation for 24 or 48 h differentiated into tenocytes. Atomic force microscopy (AFM) was then used to measure the force curves around the cell nuclei, and the AFM data were used to calculate the elastic moduli of the cell surfaces. The elastic modulus values of the control (non-stretched) cells differed significantly from those of cells stretched at 10 % for 24 or 48 h (P < 0.01). Confocal fluorescence microscopic observations of actin stress fibers suggested that the change in elastic modulus was ascribable to the development of the cellular cytoskeleton during the differentiation process. Therefore, we conclude that the atomic force microscopic measurement of the elastic modulus of the cell surface can be used to evaluate stem cell-to-tenocyte differentiation.     

A cross-sectional epidemiological study of the relationship between sleep duration,quality, and rhythm and presenteeism in workers

Sleep and Biological Rhythms - This study aims to examine the relationship of sleep (sleep duration, sleep quality, and sleep rhythm) with presenteeism in workers while controlling for other...