Observations of an extreme form of late eccentric lytic fission in Schizosaccharomyces pombe

Abstract Late eccentric lytic fission was initially observed in Schizosaccharomyces pombe in 1967 (Johnson, B.F. (1967) J. Bacteriol. 94, 192–195). We report here an extreme form of this morphology and have studied the incidence of severity with respect to glucose concentration of the growth media. Alterations to the composition of the growth medium were made to allow cells to reach a density of 1 × 10⁸ cells ml⁻¹ before lysis occurred.     

Immunogenicity Studies with Haptenated Melittin Peptides: Implication for Membrane Involvement during the Recognition Step

Melittin peptides carrying 2,4-dinitro-6-carboxyphenyl (Dncp) haptenic groups regularly evoked anti-hapten IgG responses in mice or guinea pigs when the hapten was C-terminally attached. Single haptens on the N-terminal helix in several positions gave poor or no responses in the early stages but adequate titres after prolonged immunization. Peptides with Dncp at the C-terminus as an invariant feature and a second Dncp in various positions along the peptide chain did not fail to produce adequate responses. The hampering effect is not due to a defect at the T-cell level but involves the recognition step on the B-cell. It is implied that the haptenic interaction with the paratope of the recognizing immunoglob ulin on the B-cell involves the cell membrane in an important way. It is also suggested that late antibody responses should not be overlooked during the development of proteinaceous immunogens for vaccination.     

The late Neogene rodent succession of the Guadix–Baza Basin (south‐eastern Spain) and its magnetostratigraphic correlation

In this paper a magnetostratigraphically calibrated biozonation of the Miocene–Pliocene continental record of the Guadix–Baza Basin (south‐eastern Spain) is presented. This biozonation is based on a rodent succession which ranges from the latest Miocene (c. 6 Ma) to the latest Pliocene (c. 2.6 Ma). A total of nine biozones have been defined for the late Miocene and Pliocene, all of them based on the range or concurrent‐range of rodent species: Apodemus gudrunae – Apocricetus alberti Zone, Apocricetus barrierei Zone, Paraethomys aff. abaigari Zone, Trilophomys Zone, Mimomys davakosi Zone, Dolomys adroveri Zone, Mimomys hassiacus Zone, Mimomys polonicus Zone and Kislangia ischus Zone. A magnetobiostratigraphical correlation has been established between these biozones and the standard ATNTS scale, on the basis of the palaeomagnetic analysis carried out on the sections of Negratín, Botardo‐1 and Gorafe. The correlation has been completed with previous palaeomagnetic analysis in the sections of Galera and Zújar. The magnetobiostratigraphical correlation here established indicates a late Messinian age for the Apodemus gudrunae – Apocricetus alberti Zone, a Zanclean age for the Apocricetus barrierei, Paraethomys aff. abaigari, Trilophomys and Mimomys davakosi zones and a Piazencian age for the Mimomys hassiacus, Mimomys polonicus and Kislangia ischus zones. The Dolomys adroveri Zone is mostly Zanclean in age, but its uppermost part belongs to the Piazencian. Therefore, unit MN13 is correlated with the late Messinian, MN14 is correlated with the early Zanclean, most of MN15 is correlated with the late Zanclean, while the uppermost part of MN15 and MN16 are correlated with the Piazencian.     

湖南界岭邵东段微体植物群

湖南界岭微体植物群由５６属１４５种小孢子及很少量的疑源类与虫牙组成,并以Ｓｐｅｌａｅｏｔｒｉｌｅｔｅｓ ｈｕｎａｎｅｎｓｉｓ的百分含量最高和同时含泥盆纪与石炭纪双重时代色彩的分子为特征。但其地质时代属晚泥盆世晚期或晚法门期。     

When east met west: the sub-fossil footprints of the west European hedgehog and the northern white-breasted hedgehog during the Late Quaternary in Europe

The distinct distribution of the west European hedgehog Erinaceus europaeus and the northern white-breasted hedgehog Erinaceus roumanicus and their separate refugial origins after the Pleistocene is a well-known example in the zoogeography of the Holarctic. Among the Late Quaternary faunal assemblages, the west European hedgehog is recorded at 269 sites whereas the northern white-breasted hedgehog is recorded only at 52 sites in Europe. The distribution patterns of the temporal and spatial Glacial records of the west European hedgehog show a general trend: a strong restriction to glacial refugia (the Iberian and Italian Peninsulas) during the Weichselian Glacial until the end of the Last Glacial Maximum, and a colonization of southern France during the early Late Glacial between 14 000 and 125 00 ¹⁴C years BP (15 000–12 800 cal. BC). Whereas the British Isles could have already been colonised by the end of the Pre-Boreal, in the rest of Central Europe E. europaeus was clearly distributed there in the Boreal for the first time. The west European hedgehog is an absolute Holocene faunal element in Central Europe. It appears in most parts of Central Europe during the Early Holocene, when the west European hedgehog met its eastern relative, which probably was similarly sensitive. After meeting each other, the distribution limit of both Erinaceus species in Central Europe seems to have been relatively constant in its geographic extent. Because of the clear climatic correlation, E. europaeus should be considered as an indicator species for temperate climatic conditions of the Holocene fauna. This should be considered during the reconstruction of climatic conditions with the help of the analysis of quaternary faunal material.     

Release of 6-KETO-PGF1α and thromboxane B2 in late appearing cardioprotection induced by the stable PGI analogue: 7-OXO-PGI

We have shown earlier that prostacylin (PGI₂) and its stable analogue: 7-oxo-prostacyclin(7-OXO) may induce a prolonged, late appearing (24–48 h after drug administration), dose dependent protection of the heart from harmful consequences of a subsequent severe ischaemic stress, such as myocardial ischaemia, life-threatening ventricular arrhythmias and early ischaemic morphological changes. In an other study we observed that a similar but shortlived (less than 1 h) cardioprotection, induced by preconditioning brief coronary artery occlusions, is greatly reduced by blockade of the cyclooxygenase pathway, suggesting that prostanoids might play a role in this shortlasting protection.Objective of our present study was to elucidate the importance of some arachidonic acid (AA) metabolites, such as PGI₂ and thromboxane A₂ (TXA₂) in the mechanism of the late appearing, prolonged cardioprotection. Estimation of the metabolites: 6-keto-PGF₁ (6-KETO) and thromboxane B₂ (TXB₂) was made from the perfusate of isolated Langendorff hearts of guinea-pigs pretreated with 50 g/kg 7-OXO, 24 and 48 h before preparation. Pretreatment alone produced a slight, but significant elevation of 6-KETO (from 206±11 to 284±19 pg/ml/min after 24 h, and to 261±18 pg/ml/min after 48 h). No change was seen in TXB₂ production. Global ischaemia for 25 min (followed by 25 min reperfusion) markedly increased the release of both AA metabolites; maximal values were observed in the third min of reperfusion (6-KETO from 206±11 to 1275±55 pg/ml/min and TXB₂ from 29±4 to 172±12 pg/ml/min). All values returned to the preischaemic level by the 25th min of reperfusion. Ischaemic increase in 6-KETO level was significantly higher in the perfusate of hearts from pretreated animals (1507±73 pg/ml/min after 24 h, and 1398±54 pg/ml/min after 48 h) that in those of untreated controls. There was no difference in TXB₂ values. Thus both basal and ischaemic release of PGI₂ increased 24 and 48 h after pretreatment with 7-OXO but not TXA₂ production. Results suggest that endogenous prostanoids might play a role in late appearing cardioprotection.     

Evidence for sequential action of Rab5 and Rab7 GTPases in prevacuolar organelle partitioning

GTPases of the Rab5 and Rab7 families were shown to control vacuolar sorting but their specific subcellular localization is controversial in plants. Here, we show that both the canonical as well as the plant-specific Rab5 reside at the newly discovered 'late prevacuolar compartment' (LPVC) while Rab7 partitions to the vacuolar membrane when expressed at low levels. Higher expression levels of wild-type Rab5 GTPases but not Rab7 lead to dose-dependent inhibition of biosynthetic vacuolar transport. In the case of Ara6, this included aberrant co-localization with markers for earlier post-Golgi compartments including the trans-Golgi network. However, nucleotide-free mutants of all three GTPases (Rha1, Ara6 and Rab7) cause stronger dose-dependent inhibition of vacuolar sorting. In addition, nucleotide-free Rha1 led to a later maturation defect and co-localization of markers for the prevacuolar compartment (PVC) and the LPVC. The corresponding Rab7 mutant strongly inhibited vacuolar delivery without merging of PVC and LPVC markers. Evidence for functional differentiation of the Rab5 family members is underlined by the fact that mutant Rha1 expression can be suppressed by increasing wild-type Rha1 levels while mutant Ara6 specifically titrates the nucleotide exchange factor Vps9. A model describing the sequential action of Rab5 and Rab7 GTPases is presented in the light of the current observations.     

Sequence variation of intergenic mitochondrial DNA spacers (mtDNA‐IGS) of Phytophthora infestans (Oomycetes) and related species

The potato late‐blight disease is caused by the pseudofungus Phytophthora infestans (Oomycetes). This pathogen was of historical importance as it caused the Irish Potato Famine. There is currently a worldwide resurgence of the disease. Following worldwide migrations as well as being able to discriminate P. infestans from related species are key issues. We present sequence variation of five inter‐genic mitochondrial DNA spacers (mtDNA‐IGS) for P. infestans and four related taxa. Intra and inter‐taxon variation was observed showing potential for both molecular ecology and molecular systematic.