Pollen-derived history of timber exploitation from the Roman period onwards in the Romanche valley, central French Alps

The history of forestry in the Romanche river valley, south-east of Grenoble, France, is reconstructed for the past ca. 3000 years on the basis of detailed pollen analysis and AMS¹⁴C dating. Three deforestation phases are recorded during the last two millennia, each phase showing different features and also contrasting woodland succession in the post-clearance period. The first major deforestation is recorded at the Roman time whenAbies alba (fir) was selectively exploited, presumably for use by peoples living downstream of the site. Apart from the deforestation, there appears to have been little human activity in the vicinity of the site at this time. After the clearance fir gradually, and more or less fully, recovered. The second deforestation phase occurred in ca. the 5^th and 6^th century A.D. when there is also substantial evidence for local farming. At this time, both fir and beech (Fagus sylvatica) were non-selectively exploited and probably used locally. Beach subsequently recovers but there is no further regeneration of fir. The third deforestation phase in ca. the 12^th century A.D. is similar to the preceding phase but this time beech does not recover. With the decline in human activity, secondary forest that included spruce (Picea) and pine (Pinus), developed. Forest dynamics were controlled by local human activity and also the economic relationships between the local area and the wider region and especially the region downstream from the site.     

Novel matrix metalloproteinase inhibitors: generation of lead compounds by the in silico fragment-based approach

Generation of structurally new matrix metalloproteinase inhibitors was successfully carried out using an in silico technique. In order to identify the small fragment interacting with residues in the S1' pocket of MMP-1 through hydrogen bonds, we performed in silico screening using the LUDI program. As a result, acetyl-L-alanyl-(N-methyl)amide (Ac-L-Ala-NHMe) was selected to link with another fragment, hydroxamic acid that interacted with catalytic zinc. By this approach, the L-glutamic acid derivative 2b was discovered to be a new type of matrix metalloproteinase inhibitor. Further transformation to reduce its peptidic nature and improve activity yielded nonpeptidic lead compounds as inhibitors of MMP-1, -2, -3, and -9.     

The <Emphasis Type="Italic">Endo-β-Mannanase</Emphasis> gene families in <Emphasis Type="Italic">Arabidopsis</Emphasis>, rice,and poplar

Mannans are widespread hemicellulosic polysaccharides in plant cell walls. Hydrolysis of the internal β-1,4-d-mannopyranosyl linkage in the backbone of mannans is catalyzed by endo-β-mannanase. Plant endo-β-mannanase has been well studied for its function in seed germination. Its involvement in other plant biological processes, however, remains poorly characterized or elusive. The completed genome sequences of Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa), and poplar (Populus trichocarpa) provide an opportunity to conduct comparative genomic analysis of endo-β-mannanase genes in these three species. In silico sequence analysis led to the identification of eight, nine and 11 endo-β-mannanase genes in the genomes of Arabidopsis, rice, and poplar, respectively. Sequence comparisons revealed the conserved amino acids and motifs that are critical for the active site of endo-β-mannanases. Intron/exon structure analysis in conjunction with phylogenetic analysis implied that both intron gain and intron loss has played roles in the evolution of endo-β-mannanase genes. The phylogenetic analysis that included the endo-β-mannanases from plants and other organisms implied that plant endo-β-mannanases have an ancient evolutionary origin. Comprehensive expression analysis of all Arabidopsis and rice endo-β-mannanase genes showed divergent expression patterns of individual genes, suggesting that the enzymes encoded by these genes, while carrying out the same biochemical reaction, are involved in diverse biological processes.     

Three-dimensional analysis of the association of viral particles with mitochondria during the replication of Rice gall dwarf virus

Examination of cultured insect vector cells that had been infected with Rice gall dwarf virus (RGDV), using transmission electron microscopy and confocal microscopy, revealed the presence of clusters of virus-coated mitochondria around viroplasms in which replication and assembly of RGDV occurred, suggesting a role for mitochondria in supplying the energy required for viral morphogenetic processes. Electron tomography revealed that RGDV particles on the surface of mitochondria are arrayed in an orderly but loose manner, unlike tightly packaged particles in vesicular compartments, suggesting the presence of counterpart molecules on the surface of mitochondria. The viral particles in close proximity to mitochondria were aligned along intermediate filaments, which might serve as scaffolds for the anchorage of these particles. RGDV has a putative mitochondrion-targeting sequence on the outer surface of the outer-capsid protein P8. The arrangement of RGDV particles around mitochondria suggests that the region of the P8 protein containing the mitochondrion-targeting sequence might attach to a molecule like a receptor on the outer mitochondrial membrane. Our analysis demonstrates the three-dimensional arrangement and molecular basis for the mitochondrial proximity of RGDV particles during viral replication.     

In vitro development of polyspermic porcine oocytes: Relationship between early fragmentation and excessive number of penetrating spermatozoa

Embryo development during in vitro culture of polyspermic porcine oocytes was investigated in the present study. After in vitro fertilization (IVF) of in vitro matured oocytes, putative zygotes were centrifuged to visualize pronuclei. Two pronuclear (2PN) and poly-pronuclear (PPN) zygotes were selected and cultured in vitro. Their development to the blastocyst stage and total cell numbers, dead cell rates and ploidy at the blastocyst stage and morphology of resultant embryos after first cleavage were compared. A cleavage rate of PPN embryos was lower than that of 2PN (61.3% and 82.2%, respectively), however, the ability of cleaved embryos to develop to the blastocyst stage did not differ between the PPN and the 2PN groups (22.4% and 32.9%, respectively). Also there was no difference in total cell numbers and rates of dead cells between PPN and 2PN blastocysts. The majority of blastocysts in 2PN group were found to be diploid. In contrast, blastocysts in PPN group showed heterogeneous status in their ploidy including polyploidy and mixoploidy, whereas a remarkable proportion (31.3%) of them was found to be diploid. After the first cleavage (at 36 h after IVF), there was no difference in the number of nuclei/embryo between the two groups, nevertheless embryos in PPN group had significantly higher numbers of blastomeres than that of embryos in 2PN group, mainly due to an increased frequency of anuclear blastomeres. The present results indicate that correction of embryo ploidy in polyspermic embryos can occur during IVC. Nevertheless the frequency of partial fragmentation in polyspermic embryos is increased.     

Meiotic and epigenetic aberrations in Dnmt3L-deficient male germ cells

The DNA methyltransferase-like protein Dnmt3L is necessary for the establishment of genomic imprints in oogenesis and for normal spermatogenesis (Bourc'his et al., 2001; Hata et al., 2002). Also, a paternally imprinted gene, H19, loses DNA methylation in Dnmt3L-/- spermatogonia (Bourc'his and Bestor, 2004; Kaneda et al., 2004). To determine the reason for the impaired spermatogenesis in the Dnmt3L-/- testes, we have carried out a series of histological and molecular studies. We show here that Dnmt3L-/- germ cells were arrested and died around the early meiotic stage. A microarray-based gene expression-profiling analysis revealed that various gonad-specific and/or sex-chromosome-linked genes were downregulated in the Dnmt3L-/- testes. In contrast, expression of retrovirus-like intracisternal A-particle (IAP) sequences was upregulated; consistent with this observation, a specific IAP copy showed complete loss of DNA methylation. These findings indicate that Dnmt3L regulates germ cell-specific gene expression and IAP suppression, which are critical for male germ cell proliferation and meiosis.     

Overexpression of glutathione peroxidase attenuates myocardial remodeling and preserves diastolic function in diabetic heart

Oxidative stress plays an important role in the structural and functional abnormalities of diabetic heart. Glutathione peroxidase (GSHPx) is a critical antioxidant enzyme that removes H(2)O(2) in both the cytosol and mitochondia. We hypothesized that the overexpression of GSHPx gene could attenuate left ventricular (LV) remodeling in diabetes mellitus (DM). We induced DM by injection of streptozotocin (160 mg/kg ip) in male GSHPx transgenic mice (TG+DM) and nontransgenic wildtype littermates (WT+DM). GSHPx activity was higher in the hearts of TG mice compared with WT mice, with no significant changes in other antioxidant enzymes. LV thiobarbituric acid-reactive substances measured in TG+DM at 8 wk were significantly lower than those in WT+DM (58 +/- 3 vs. 71 +/- 5 nmol/g, P < 0.05). Heart rate and aortic blood pressure were comparable between groups. Systolic function was preserved normal in WT+DM and TG+DM mice. In contrast, diastolic function was impaired in WT+DM and was improved in TG+DM as assessed by the deceleration time of peak velocity of transmitral diastolic flow and the time needed for relaxation of 50% maximal LV pressure to baseline value (tau; 13.5 +/- 1.2 vs. 8.9 +/- 0.7 ms, P < 0.01). The TG+DM values were comparable with those of WT+Control (tau; 7.8 +/- 0.2 ms). Improvement of LV diastolic function was accompanied by the attenuation of myocyte hypertrophy, interstitial fibrosis, and apoptosis. Overexpression of GSHPx gene ameliorated LV remodeling and diastolic dysfunction in DM. Therapies designed to interfere with oxidative stress might be beneficial to prevent cardiac abnormalities in DM.     

Neurokinin A-like immunoreactivity in feline dental pulp: its distribution,origin and coexistence with substance P-like immunoreactivity

Summary The distribution and origin of neurokinin A (NKA)-like immunoreactivity were investigated in feline dental pulp by an indirect immunofluorescence method. NKA-containing nerve fibres with varicosities, which entered the dental pulp via apical foramen, were distributed throughout this tissue. Many NKA-containing nerve fibres were localized around blood vessels, but some were observed apart therefrom. At the odontoblastic layer, thin NKA-containing nerve fibres were observed running straight toward the pulp-predentinal border between odontoblasts. After inferior alveolar nerve section, all NKA-containing nerve fibres disappeared in the dental pulp, while the removal of the superior cervial ganglion resulted in no change in the distribution of these fibres. The correlation of NKA-like immunoreactivity and substance P (SP)-like immunoreactivity was also investigated by double-immunofluorescence technique. The distribution of NKA-containing nerve fibres was very similar to that of SP-containing nerve fibres; it appeared that all NKA-containing nerve fibres contained SP.