Oocyte mitochondria: Strategies to improve embryogenesis

Mitochondria play a central role to provide ATP for fertilization and preimplantation embryo development in the ooplasm. The mitochondrial dysfunction of oocyte has been proposed as one of the causes of high levels of developmental retardation and arrest that occur in preimplantation embryos generated using Assisted Reproductive Technology. Cytoplasmic transfer (CT) from a donor to a recipient oocyte has been applied to infertility due to dysfunctional ooplasm, with resulting pregnancies and births. However, neither the efficacy nor safety of this procedure has been appropriately investigated. In order to improve embryogenesis, we observed the mitochondrial distribution in ooplasma under the several conditions using mitochondrial GFP-transgenic mice (mtGFP-tg mice) in which the mitochondria are visualized by GFP. In this report, we will present our research about the mitochondrial distribution in ooplasm during early embryogenesis and the fate of injected donor mitochondria after CT using mtGFP-tg mice. The mitochondria in ooplasm from the germinal vesicle stage to the morula stage were accumulated in the perinuclear region. The mitochondria of the mtGFP-tg mouse oocyte transferred into the wild type mouse embryo could be observed until the blastocysts stage, suggesting that the mtGFP-tg mice oocyte is very useful for visual observation of the mitochondrial distribution in the oocyte, and that the aberrant early developmental competences due to the oocyte mitochondrial dysfunction may be overcome by transferring the "normal" mitochondria.     

Internal architecture, origin-insertion site, and mass of jaw muscles in Old World hamsters

The jaw muscle (i.e., masticatory, suprahyoid, and extrinsic tongue) anatomy and mass were examined in four genera of Old World hamsters (cricetine murids), Mesocricetus, Cricetulus, Tscherskia, and Phodopus. The masseter was the largest and most complicated of the muscles examined. In the superficial layer, a few ventral fibers form a small medially turned portion with an insertion site more similar to those of sciurids than of other murids. In Mesocricetus, the superficial layer has a discrete anteroventral portion that has not been reported for other murid rodents. Examination of the fiber attachment sites indicated that the deep layer contains four parts and the medial layer contains three parts. The deep layer originates from two aponeuroses that are firmly connected to each other at their anterior ends and lie along the zygomatic arch. The aponeurosis of insertion for the deep layer is situated along the masseteric ridge and the dorsal border of the angular process, but is absent in its middle part, consistent with reports in two relatives, sigmodontine and arvicoline murids. In cricetine murids, unlike in other rodents, fibers insert on the dorsal narrow strip of the posterior mandibular aponeurosis, not on its broad medial aspect. The relative mass of some masticatory and suprahyoid muscles is related to body mass. Small species (Cricetulus and Phodopus) have relatively larger masseter and mylohyoid muscles and smaller temporalis and geniohyoid muscles than large species (Mesocricetus and Tscherskia).     

Renal organs of cephalopods: a habitat for dicyemids and chromidinids

The renal organs of 32 species of cephalopods (renal appendage of all cephalopods, and renal and pancreatic appendages in decapods) were examined for parasite fauna and for histological comparison. Two phylogenetically distant organisms, dicyemid mesozoans and chromidinid ciliates, were found in 20 cephalopod species. Most benthic cephalopods (octopus and cuttlefish) were infected with dicyemids. Two pelagic cephalopod species, Sepioteuthis lessoniana and Todarodes pacificus, also harbored dicyemids. Chromidinid ciliates were found only in decapods (squid and cuttlefish). One dicyemid species was found in branchial heart appendages of Rossia pacifica. Dicyemids and chromidinids occasionally occurred simultaneously in Euprymna morsei, Sepia kobiensis, S. peterseni, and T. pacificus. The small-sized cephalopod species, Idiosepius paradoxus and Octopus parvus, harbored no parasites. Comparative histology revealed that the external surface of renal organs varies morphologically in various cephalopod species. The small-sized cephalopod species have a simple external surface. In contrast, the medium- to large-sized cephalopod species have a complex external surface. In the medium- to large-sized cephalopod species, their juveniles have a simple external surface of the renal organs. The external surface subsequently becomes complicated as they grow. Dicyemids and chromidinids attach their heads to epithelia or insert their heads into folds of renal appendages, pancreatic appendages, and branchial heart appendages. The rugged and convoluted external surface provides a foothold for dicyemids and chromidinids with a conical head. They apparently do not harm these tissues of their host cephalopods.     

Over-expression of the testis-specific gene TSGA10 in cancers and its immunogenicity

The TSGA10 gene was originally isolated in normal testis by differential mRNA display. TSGA10 is located on chromosome 2q11.2 and consists of 19 exons extending over 3 kb. TSGA10 mRNA expression was investigated in normal and malignant tissues using quantitative real-time RT-PCR. It was predominantly expressed in the testis in adult normal tissues. In malignant tissues, TSGA10 was over-expressed in 4 of 20 hepatocellular carcinomas (HCC), 1 of 20 colon cancers, 7 of 20 ovarian cancers, 3 of 20 prostate cancers, 1 of 21 malignant melanomas, and 8 of 21 bladder cancers. Serological analysis revealed that 3 out of 346 patients with various types of cancer possessed antibody against recombinant TSGA10 protein. They included 2 patients with hepatocellular carcinoma and a patient with malignant melanoma.     

Accumulation of HDMBOA-Glc is induced by biotic stresses prior to the release of MBOA in maize leaves

The effects of biotic stresses on the contents of benzoxazinones (Bxs) were investigated in maize leaves. When the causal agent of southern corn leaf blight, Bipolaris maydis, was inoculated on the third leaf, the amount of 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside (HDMBOA-Glc) increased, reaching a maximum level 48 h after inoculation. The inoculation of weakly pathogenic Curvularia lunata and non-pathogenic Alternaria alternata also resulted in accumulation of HDMBOA-Glc, and filtrates of the cultures of B. maydis, C. lunata and A. alternata also showed the accumulation of elicitor-active compounds by the fungi. Furthermore the infection of B. maydis induced formation of dark brown lesions, where most abundant Bx-related compound was 6-methoxy-2-benzoxazolinone (MBOA). The later is formed by degradation of DIMBOA and HDMBOA, whereas HDMBOA-Glc was most abundant in the surrounding green tissues. Among the Bx-related compounds, MBOA exhibited the strongest inhibition of the germination of the conidia and of the growth of germ tubes of B. maydis, C. lunata and A. alternata. In addition to fungal infection, the feeding by rice armyworm larvae resulted in HDMBOA-Glc accumulation. These findings are discussed in relation to the possible ecological relevance of the conversion of DIMBOA-Glc into HDMBOA-Glc.     

Genomic basis for cell-wall diversity in plants. A comparative approach to gene families in rice and Arabidopsis

Monocotyledons and dicotyledons are distinct, not only in their body plans and developmental patterns, but also in the structural features of their cell walls. The recent completion of the rice (Oryza sativa) genomic sequence and publication of the sequence data, together with the completed database of the Arabidopsis thaliana genome, provide the first opportunity to compare the full complement of cell-wall-related genes from the two distinct classes of flowering plants. We made this comparison by exploiting the fact that Arabidopsis and rice have type I and type II walls, respectively, and therefore represent the two extremes in terms of the structural features of plant cell walls. In this review article, we classify all cell-wall-related genes into 32 gene families, and generate their phylogenetic trees. Using these data, we can phylogenetically compare individual genes of particular interest between Arabidopsis and rice. This comparative genome approach shows that the differences in wall architecture in the two plant groups actually mirror the diversity of the individual gene families involved in the cell-wall dynamics of the respective plant species. This study also identifies putative rice orthologs of genes with well-defined functions in Arabidopsis and other plant species.     

Regulation of ghrelin secretion during pregnancy and lactation in the rat: possible involvement of hypothalamus

We investigated the plasma concentration of ghrelin peptide during pregnancy and lactation in rats. Plasma ghrelin levels on days 10 and 15 of pregnancy were significantly lower than those of the non-pregnant rats. Thereafter, the plasma ghrelin levels on day 20 of pregnancy sharply increased to levels comparable with those in non-pregnant rats. Ghrelin peptide concentrations in the stomach did not change significantly during pregnancy. In the hypothalamus, ghrelin mRNA levels were significantly lower on day 15 of pregnancy than in the non-pregnant rats. Also, plasma ghrelin levels were significantly lower in lactating dams than non-lactating controls on days 3 and 8 of lactation. We examined the possible involvement of prolactin and oxytocin in the regulation of plasma ghrelin concentrations during lactation. Although plasma prolactin levels were decreased by the administration of bromocriptine, plasma ghrelin levels did not differ significantly between vehicle- and drug-treated lactating rats. Administration of haloperidol produced a marked increase in plasma prolactin levels as compared with the non-lactating controls. However, plasma ghrelin levels were not significantly different between vehicle- and drug-treated rats. Administration of an oxytocin antagonist into the lateral ventricle significantly inhibited the increase in the plasma oxytocin level induced by acute suckling. However, plasma ghrelin levels did not significantly between the groups. These observations indicated that the decrease in serum ghrelin is caused by a loss of the contribution of hypothalamic ghrelin. Furthermore, the present results suggested that the suckling stimulus itself, but the release of prolactin or oxytocin, is the factor most likely to be responsible for the suppression of ghrelin secretion during lactation.     

2-Ureidoquinoline: a useful molecular element for stabilizing single cytosine and thymine bulges

We have demonstrated that aromatic heterocycles having hydrogen-bonding surfaces complementary to those of nucleotide bases are effective molecular elements for the binding to single nucleotide bulges and base mismatches. We here report that a new molecule, 2-ureidoquinoline having an alignment of hydrogen-bonding groups in the order of acceptor-donor-donor stabilizes single cytosine and thymine bulges in duplex DNAs. Furthermore, a dimeric form of 2-ureidoquinoline stabilizes cytosine-cytosine and cytosine-thymine mismatches.     

Secular trends of sizes at birth in Japanese healthy infants born between 1962 and 1988

Body sizes at birth are important clinical indicators widely used for evaluation of prenatal growth. Japan had significant socioeconomic improvement around the 1960s, and these environmental changes may influence physiologically prenatal growth. Furthermore, in Japan, measurements of size at birth for birth certificates are weight and height. Thus, we can refer to annual data on weight and height, but not on head and chest circumference at birth. In this study we measured the weight, height, and head and chest circumference at birth among 6,563 Japanese singleton healthy infants, annually in 1962 and 1988, and examined secular trends of these anthropometric measurements. The boys consistently exceeded the girls in all four variables. Birth weight and height increased significantly from the 1960s to '70s, but did not differ between the '70s and '80s in both boys and girls. Secular trends of head and chest circumference were different from them. In both boys and girls, head and chest circumference increased significantly from the '60s to the '70s, but decreased significantly from the '70s to the '80s. No difference of head circumference during the '60s and '80s was found, but the difference of chest circumference was found. Size at birth was likely to increase from the '60s to '70s in Japan. These findings suggest that the environmental changes such as socioeconomic improvements influence the prenatal growth.     

Cell-passage activity is required for the malarial parasite to cross the liver sinusoidal cell layer

Liver infection is an obligatory step in malarial transmission, but it remains unclear how the sporozoites gain access to the hepatocytes, which are separated from the circulatory system by the liver sinusoidal cell layer. We found that a novel microneme protein, named sporozoite microneme protein essential for cell traversal (SPECT), is produced by the liver-infective sporozoite of the rodent malaria parasite, Plasmodium berghei. Targeted disruption of the spect gene greatly reduced sporozoite infectivity to the liver. In vitro cell invasion assays revealed that these disruptants can infect hepatocytes normally but completely lack their cell passage ability. Their apparent liver infectivity was, however, restored by depletion of Kupffer cells, hepatic macrophages included in the sinusoidal cell layer. These results show that malarial sporozoites access hepatocytes through the liver sinusoidal cell layer by cell traversal motility mediated by SPECT and strongly suggest that Kupffer cells are main routes for this passage. Our findings may open the way for novel malaria transmission-blocking strategies that target molecules involved in sporozoite migration to the hepatocyte.