Oxytocin hypersensitivity in pregnant P-LAP deficient mice

AimsOxytocin (OT) is the strongest uterotonic substance and has been used widely to induce labor. The physiological importance of OT in modulating the initiation and progression of labor remains unclear. In this study, we showed the roles of OT with onset of labor and also the arginine vasopressin (AVP) effect on urine volume in vivo using both wild type (WT) and placental leucine aminopeptidase (P-LAP)-deficient (KO) mice.Main methodsOT (1, 2, 2.5 U/day) or recombinant P-LAP (0.01 U/day) was continuously infused from gestation day 15.5 in WT and P-LAP KO mice. Duration until onset of labor was observed. Before and after administration of AVP (1 U/day) in WT and P-LAP KO mice, urine volume was measured.Key findingsA significant shortening of pregnancy term was observed in P-LAP KO mice. Continuous infusion of OT (1 U/day) revealed that P-LAP KO mice resulted in premature delivery (OT hypersensitivity). We could observe a significant decrease of urine volume in P-LAP KO mice by administration of AVP. Administration of recombinant P-LAP in WT mice resulted in the delay of the onset of labor about 1.5 days compared with control mice.SignificanceOur present study shows that the regulation of the onset of labor mainly depends on OT and its degradation by P-LAP and also the possible role of P-LAP in the regulation of urine output. P-LAP might be involved in the increased OT sensitivity just prior to onset of labor and also in the onset of labor by degradation of OT.     

Faunal turnover at the end of the Cretaceous in the North Pacific region: Implications from combined magnetostratigraphy and biostratigraphy of the Maastrichtian Senpohshi Formation in the eastern Hokkaido Island,northern Japan

A combined magnetostratigraphic and biostratigraphic study has been performed on the Maastrichtian Senpohshi Formation in eastern Hokkaido Island, northern Japan, which is an approximately 1300 m thick section mainly composed of hemipelagic mudstone. The identification of magnetic polarity was possible at 51 horizons, whereby four magnetozones were recognized. These magnetozones were correlatable to geomagnetic polarity chrons C31r to C30n, suggesting that the age of the Senpohshi Formation is spanning from middle to upper part of the Maastrichtian (ca. 69–67 Ma).The magnetostratigraphy of the Senpohshi Formation established in this study enables a direct age correlation to the Maastrichtian successions in other regions. Thus, this detailed chronology of the formation contributes to paleontological studies of the Maastrichtian in the North Pacific region. For instance, this magnetostratigraphic age assessment implies the following: (1) the stratigraphic range of the ammonite Pachydiscus flexuosus contains polarity chrons from the lower part of C31r to the lower part of C31n, (2) the first occurrence (FO) of the calcareous nannofossil Nephrolithus frequens in the North Pacific region is correlatable to polarity chron C30n or below, and (3) the FO of the bivalve “Inoceramus” awajiensis is located within polarity chrons from C31r to the upper part of C31n. This suggests that the inoceramid extinction event in the North Pacific region might have occurred during polarity chrons from C31r to the upper part of C31n (ca. 70.5–67.8 Ma), which is 2.3–5.0 Myr prior to the Cretaceous/Paleogene boundary. The trend of the Maastrichtian faunal turnover in the North Pacific is well consistent with those of other regions, brings a new evidence for understanding the global faunal turnover in the Maastrichtian, just before Cretaceous/Paleogene mass extinction.     

Axotomy induces axonogenesis in hippocampal neurons by a mechanism dependent on importin β

We characterize the previously unrecognized phenomenon of axotomy-induced axonogenesis in rat embryonic hippocampal neurons in vitro and elucidate the underlying mechanism. New neurites arose from cell bodies after axotomy and grew. These neurites were Tau-1-positive, and the injured axons showed negative immunoreactivity for Tau-1. Axonogenesis was delayed in these neurons by inhibiting the dynein–dynactin complex through the overexpression of p50. Importin β, which was locally translated after axotomy, was associated with the dynein-importin α complex and was required for axonogenesis. Taken together, these results suggest that retrograde transport of injury-induced signals in injured axons play key roles in the axotomy-induced axonogenesis of hippocampal neurons.     

The association between HLA-A alleles and an Alu dimorphism near HLA-G

The AluYb8 sequences are a subfamily of short interspersed Alu retroelements that have been amplified within the human genome during recent evolutionary time and are useful polymorphic markers for studies on the origin of human populations. We have identified a new member of the Yb8 subfamily, AluyHG, located between the HLA-H and -G genes and 88-kb telomeric of the highly polymorphic HLA-A gene within the alpha block of the major histocompatibility complex (MHC). The AluyHG element was characterised with a view to examining the association between AluyHG and HLA-A polymorphism and reconstructing the history of the MHC alpha block. A specific primer pair was designed for a simple PCR assay to detect the absence or presence (dimorphism) of the AluyHG element within the DNA samples prepared from a panel of 46 homozygous cell-lines containing complete or recombinant ancestral haplotypes (AH) of diverse ethnic origin and 92 Caucasoid and Asian subjects on which HLA-A typing was available. The AluyHG insertion was most strongly associated with HLA-A2 and, to a lesser degree with HLA-A1, -A3, -A11, and A-19. The gene frequency of the AluyHG insertion for 146 Caucasians and 94 Chinese-Han was 0.30 and 0.32 and there was no significant difference between the observed and expected frequencies. The results of the association studies and the phylogenetic analysis of HLA-A alleles suggest that the AluyHG sequence was integrated within the progenitor of HLA-A2, but has been transferred by recombination to other human ancestral populations. In this regard, the dimorphic AluyHG element is an important diagnostic marker for HLA association studies and could help in elucidating the evolution and functions of the MHC alpha block and polymorphism within and between ancestral haplotypes. Received: 7 December 2000 / Accepted: 28 February 2001     

Photoperiod- and temperature-dependent regulation of pupal beige/black polymorphism in the small copper butterfly, Lycaena phlaeas daimio Seitz

The small copper butterfly, Lycaena phlaeas daimio, has pupal beige/black polymorphism, the development of which is found to be controlled in an apparent association with the development of adult seasonal polymorphism (spring and summer morphs) by photoperiod and temperature in the larval stages. That is, the pupae of beige and black types developed under long-day and short-day conditions tend to develop into brown-winged and red-winged adults, respectively. In addition, a large proportion of long-day pharate pupae chilled at 4 degrees C for 5 days were observed to develop into pupae whose head-thoracic complexes and abdomens were judged to be of the black and intermediate types, respectively. They developed into adults with redder wings as compared to those obtained from unchilled pupae. The results indicate that the physiological mechanism underlying the photoperiodic control of the development of adult seasonal polymorphism may also play a significant role in the determination of pupal beige/black polymorphism in L. phlaeas daimio. Furthermore, cuticle melanization was found to be induced in the head-thoracic complexes of pupae by chilling of the pharate pupae. Melanization of pupal cuticle seems to occur in a close association with the development of reddish-winged adults.     

Effects of protein transport inhibitors on the distribution and secretion of the fusion protein RntA-EGFP in Aspergillus oryzae

The distribution of the secreted protein ribonuclease T1 (RntA) fused with the enhanced green fluorescent protein (EGFP), RntA-EGFP, was visualized in hyphae of Aspergillus oryzae in the presence of a protein transport inhibitor, brefeldin A, cytochalasin A, or nocodazole. During treatment with the protein transport inhibitors, the distribution of RntA-EGFP changed and distinct patterns of fluorescence accumulation were observed. The addition of brefeldin A caused RntA-EGFP fluorescence to appear in reticular networks, and the disruption of the polymerization of actin filaments by cytochalasin A caused an increase in RntA-EGFP fluorescence intensity in the hyphae without accumulation in a specific cellular component. In contrast, RntA-EGFP fluorescence was distributed in different parts of a hypha during treatment with nocodazole, a compound that depolymerizes microtubules. In addition, quantitative analysis was performed using the RntA-EGFP visualization system to analyze the relative amount of RntA-EGFP secreted into the culture medium during treatment with the protein transport inhibitors.     

Temporal and spatial variation of forest biomass in relation to stand dynamics in a mature,lowland tropical rainforest,Malaysia

To clarify consistency in the size of carbon pool of a lowland tropical rainforest, we calculated changes in above-ground biomass in the Pasoh Forest Reserve, Peninsular Malaysia. We estimated the total above-ground biomass of a mature stand using tree census data obtained in a 6-ha plot every 2years from 1994 to 1998. The total above-ground biomass decreased consistently from 1994 (431Mgha^–1) to 1998 (403Mgha^–1) (1Mg=10³ kg). These are much lower than that in 1973 for a 0.2ha portion of the same area, suggesting that the the total above-ground biomass reduction might have been consistent in recent decades. This trend contrasted with a major trend for neotropical forests. During 1994–1998, the forest gained 23.0 and 0.88Mgha^–1 of the total above-ground biomass by tree growth and recruitment, respectively, and lost 51.9Mgha^–1 by mortality. Overall, the biomass decreased by 28.4Mgha^–1 (i.e. 7.10Mgha^–1·year^–1), which is almost equivalent to losing a 76-cm-diameter living tree per hectare per year. Analysis of positive and negative components of biomass change revealed that deaths of large trees dominated the total above-ground biomass decrease. The forest biomass also varied spatially, with the total above-ground biomass density ranging 212–655Mgha^–1 on a 0.2-ha basis (n= 30 subplots, 1998) and 365–440Mgha^–1 on a 1ha basis. A large decrease of the total above-ground biomass density (>50Mg per ha per 2years) in several 0.2-ha subplots contributed to the overall decrease in the 6-ha total above-ground biomass. In the present study, we discuss the association between forest dynamics and biomass fluctuation, and the implication for carbon cycling in mature forests with emphasis on forest monitoring and assessments of soil and decomposition systems.     

Molecular cloning and functional characterization of avaB, a gene encoding Vam6p/Vps39p-like protein in Aspergillus nidulans

It has been demonstrated that Saccharomyces cerevisiae Vam6p/Vps39p plays a critical role in the tethering steps of vacuolar membrane fusion by facilitating guanine nucleotide exchange on small guanosine triphosphatase (GTPase) Vam4p/Ypt7p. We report here the identification and characterization of a novel protein in Aspergillus nidulans, AvaB, that exhibits similarity to Vam6p/Vps39p and plays a critical role in vacuolar morphogenesis in A. nidulans. AvaB is comprised of 1058 amino acids with amino-terminal citron homology (CNH) and central clathrin homology (CLH) domains, as observed for other Vam6p/Vps39p family proteins. Disruption of avaB in A. nidulans resulted in the fragmentation of vacuoles and reduced growth rate under various growth conditions, implying its importance in maintaining vacuolar morphology and function. Yeast two-hybrid analysis demonstrated the interaction of AvaB with AvaA, a Vam4p/Ypt7p homolog in A. nidulans, as well as the homooligomer formation of AvaB, suggesting that AvaB performs its function through hetero- or homophilic protein-protein interactions.     

The human-specific action of intermedilysin, a homolog of streptolysin O, is dictated by domain 4 of the protein

Intermedilysin is a pore-forming cytolysin belonging to the streptolysin O gene family known as the 'Cholesterol-binding/dependent cytolysins' and is unique within the family in that it is highly humanspecific. This specificity suggests interaction with a component of human cells other than cholesterol, the proposed receptor for the other toxins of the gene family. Indeed, intermedilysin showed no significant degree of affinity to free or liposome-embedded cholesterol. Characterization of intermedilysin undecapeptide mutants revealed that this lack of affinity to cholesterol was a result of the substitutions of intermedilysin in this region. Absorption assays with erythrocyte membranes from various animals, competitive inhibition with domain 4 of intermedilysin and liposome-binding assays of streptolysin O and intermedilysin indicated that cell membrane binding is the human-specific step of intermedilysin action, that the host cell membrane-binding site is located within domain 4 in common with other members of the family and that the receptor for this toxin is not cholesterol. The species specificity of undecapeptide mutants of intermedilysin and streptolysin O and chimeric mutants between intermedilysin and streptolysin O, and intermedilysin and pneumolysin indicated that domain 4 of intermedilysin determines the human-specific action step and the cell-binding site of domain 4 lies within the 56 amino acids of the C-terminal, excluding the undecapeptide region.