Egg teeth of squamate reptiles and their phylogenetic significance

Original and published data on the structure of egg teeth in squamate reptiles and the phylogenetic significance of corresponding characters are reviewed, elaborating A.M. Sergeev’s ideas on the subject. Problems are discussed concerning the use of this character in modern phylogenetic constructions and the necessity of new embryological investigations to resolve the issue concerning the formation of an unpaired egg tooth rudiment in all Squamata except the Dibamidae and Gekkota.     

Diazoxide-induced cardioprotection via DeltaPsim loss depending on timing of application

Although the role of mitochondrial ATP-sensitive potassium (mitoKATP) channels in cardioprotection is widely accepted, it remains unclear when their opening is critical for protection. We tested the hypothesis that the mitoKATP channel acts as a trigger or mediator of protection against apoptosis through loss of mitochondrial inner membrane potential (DeltaPsim). Exposure of neonatal rat cardiomyocytes to H2O2 (0.5 mmol/L) resulted in apoptosis associated with severe DeltaPsim loss. Pretreatment with diazoxide (20 to 100 micromol/L) prevented H2O2-induced apoptosis and DeltaPsim loss at 2 but not 18 h after exposure, while the latter was prevented by cotreatment with diazoxide. Lack of protection by pretreatment with diazoxide was observed in cardiomyocytes cultured in a medium containing H2O2 for 2 h and then not containing for 16 h. The slopes of the regression lines of the relationship between the proportion of apoptotic cells and DeltaPsim loss (y = -0.89 vs. -0.42) and the proportion of cells with high side scatter signal differed between cardiomyocytes exposed H2O2 for 2 and 18 h. Diazoxide per se caused a transient DeltaPsim loss (within 30 min) with a recovery followed by persistent DeltaPsim loss (after 6 h). Inhibition of the former by 5-hydroxydecanoate (5-HD, 0.5 mmol/L) abolished protection of pretreatment with diazoxide (trigger phase), while that of the latter prevented the protection of cotreatment with diazoxide (mediator phase). Our results suggest that mitoKATP channels act as a trigger and mediator of cardioprotection through a transient or persistent DeltaPsim loss depending on phenotypic consequence in response to oxidants.     

Lys-63-linked Ubiquitination by E3 Ubiquitin Ligase Nedd4-1 Facilitates Endosomal Sequestration of Internalized α-Synuclein

α-Synuclein (aS) is a major constituent of Lewy bodies, which are not only a pathological marker for Parkinson disease but also a trigger for neurodegeneration. Cumulative evidence suggests that aS spreads from cell to cell and thereby propagates neurodegeneration to neighboring cells. Recently, Nedd4-1 (neural precursor cell expressed developmentally down-regulated protein 4-1), an E3 ubiquitin ligase, was shown to catalyze the Lys-63-linked polyubiquitination of intracellular aS and thereby facilitate aS degradation by the endolysosomal pathway. Because Nedd4-1 exerts its activity in close proximity to the inner leaflet of the plasma membrane, we speculate that after the internalization of aS the membrane resident aS is preferentially ubiquitinated by Nedd4-1. To clarify the role of Nedd4-1 in aS internalization and endolysosomal sequestration, we generated aS mutants, including ΔPR1(1–119 and 129–140), ΔC(1–119), and ΔPR2(1–119 and 134–140), that lack the proline-rich sequence, a putative Nedd4-1 recognition site. We show that wild type aS, but not ΔPR1, ΔPR2, or ΔC aS, is modified by Nedd4-1 in vitro, acquiring a Lys-63-linked ubiquitin chain. Compared with the mutants lacking the proline-rich sequence, wild type-aS is preferentially internalized and translocated to endosomes. The overexpression of Nedd4-1 increased aS in endosomes, whereas RNAi-mediated silencing of Nedd4-1 decreased endosomal aS. Although aS freely passes through plasma membranes within minutes, a pulse-chase experiment revealed that the overexpression of Nedd4-1 markedly decreased the re-secretion of internalized aS. Together, these findings demonstrate that Nedd4-1-linked Lys-63 ubiquitination specifies the fate of extrinsic and de novo synthesized aS by facilitating their targeting to endosomes.     

Carbohydrate-containing cell wall polymers of some strains of the <Emphasis Type="Italic">Bacillus subtilis</Emphasis> group

A comparative study of the structures of carbohydrate-containing cell wall polymers isolated from the strains of the Bacillus subtilis group was performed by means of chemical and NMR spectroscopic meth ods. Polymers of different structure were revealed, namely, 1,3-poly(glycerol phosphates) with β-glucopyranose in Bacillus subtilis strains VKM B-520, VKM B-723, and VKM B-763 (= VKM B-911); 1,5-poly(ribitol phosphate) with α-glucopyranose in B. subtilis strains VKM B-722 and VKM B-922 (the structure is reported for the first time); and simultaneously two polymers in B. subtilis VKM B-761, 1,5-poly(ribitol phosphate) with β-glucopyranose and the disaccharide 1-phosphate polymer with the following repeating unit: -6)-α-D-Galp-(1-P-4)-gB-D-GlcpNAc-(1-, in which the hydroxyls at C3 and C6 of glucosamine residues are partially O-acetylated (the structure is reported for the first time). Heterogeneity of the B. subtilis group is con firmed by variations in the structure and composition of the cell wall polymers. The cell surface polymers are useful for discrimination of closely related bacilli strains and are cell wall marker components that may be an indispensable element of the Bacillus subtilis group taxonomy along with the genomosystematic methods.     

Preparation, characterization and pH-metric measurements of 4-hydroxysalicylidenechitosan Schiff-base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ru(III), Rh(III), Pd(II) and Au(III)

The 4-hydroxysalicylidenechitosan Schiff-base (2CS-Hdhba) was prepared by the condensation of 2,4-dihydroxybenzaldehyde with chitosan, and its metal complexes, [M(2CS-dhba)Cl₂(H₂O)₂] (M(III) = Fe, Ru, Rh), [M′(2CS-dhba)(AcO)(H₂O)₂] (M′(II) = Co, Ni, Cu, Zn), [Pd(2CS-dhba)Cl(H₂O)] and [Au(2CS-dhba)Cl₂], are reported. These complexes were characterized by elemental analysis, by spectral data (FTIR, solid-phase ¹³C NMR, UV–vis and ESR spectroscopy), by morphological observations (SEM and XRD), and by magnetic and thermal measurements. The Schiff base (2CS-Hdhba) behaves as a bidentate chelate with a single negative charge. The azomethine nitrogen and the deprotonated 2-hydroxy centres with the pendant glucosamine hydroxy functionality play no role in coordination. The dissociation constants of 2CS-Hdhba and the stability constants of some of its metal complexes have been determined pH-metrically.     

Localization of rRNA genes in the nuclear space of Calliphora erythrocephala Mg. nurse cells during polytenization

Multicolor 3D fluorescence in situ hybridization was used to study arrangement of rRNA genes in Calliphora erythrocephala nurse cell nuclei with different levels of polyteny. It has been shown that the rRNA genes are exclusively localized to chromosome 6, suggesting that chromosome 6 is the only C. erythrocephala chromosome responsible for nucleolar formation. We have also described changes in localization of ribosomal genes within the chromosome territory during polytenization, namely, that rDNA signals are detected in the peripheral region of chromosome territory starting from the stage of polytene chromosomes. In addition, it has emerged that large nucleolus associated with chromosome 6 starts to develop in the central nuclear region in the C. erythrocephala nurse cell nuclei at the stage of a primary reticular structure. The central position and nucleolar structure are retained at the stages when chromosome 6 occupies the central position, that is, at the stages of polytene and bloblike chromosomes. When the nucleus restores a reticular structure but at a higher polyteny level, the displacement of chromosome 6 to the nuclear periphery is accompanied by disruption of the large nucleolus into micronucleoli. The micronucleoli are distributed in the nuclear space retaining their association with the nucleolar-organizing regions of chromosome 6. Thus, our data suggest that the large-scale alterations in the organization of chromosome 6 and the nucleolus during polytenization are the correlated processes directly dependent on the rRNA gene activity. The earlier described dynamics of nucleolar-organizing chromosome territory and nucleolus in the nuclear space is likely to be associated with the change in the total expression activity of the nucleus, which complies with the hypothesis on the correlation between spatial nuclear organization and expression regulation of genetic material.     

Pulmonary Toxicity in Mice Following Exposure to Cerium Chloride

The widespread application of lanthanoids (Lns) in manufacturing industries has raised occupational and environmental health concerns about the possible increased health risks to humans exposed to Lns in their working and living environments. Numerous studies have shown that exposures to Ln cause pulmonary injury in animals, but very little is known about the molecular mechanisms of the pulmonary inflammation caused by cerium chloride (CeCl₃) exposure. In this study, we evaluated the oxidative stress and molecular mechanism underlying with the pulmonary inflammation associated with chronic lung toxicity in mice treated with nasally instilled CeCl₃ for 90 consecutive days. Our findings suggest that significant cerium accumulated in the lung, leading the obvious increase of the lung indices, significant increases in inflammatory cells and levels of lactate dehydrogenase, alkaline phosphate, and total protein, overproduction of reactive oxygen species and peroxidation of lipids, reduced antioxidant capacity, and pulmonary inflammation. CeCl₃ exposure also activated nuclear factor κB, increased the expression of tumor necrosis factor α, cyclooxygenase-2, heme oxygenase 1, interleukin 2, interleukin 4, interleukin 6, interleukin 8, interleukin 10, interleukin 18, interleukin 1β, and CYP1A1. However, CeCl₃ reduced the expression of nuclear factor κB (NF-κB)-inhibiting factor and heat shock protein 70. These findings suggest that the pulmonary inflammation caused by CeCl₃ in mice is closely associated with oxidative stress and inflammatory cytokine expression.     

miR-208-Induced Epithelial to Mesenchymal Transition of Pancreatic Cancer Cells Promotes Cell Metastasis and Invasion

The aim of this study was to investigate the role of miR-208 in the invasion and metastasis of pancreatic cancer cells and the underlying molecular mechanism. miR-208 mimic, miR-208 inhibitor and NC were transfected into pancreatic cancer cell line Bxpc3 using liposome. Transwell invasion and scratch assays were used to test cell migratory and invasive abilities. Western blotting and quantitative PCR methods were used to detect E-cadherin, fibronectin and vimentin protein and mRNA expression in pancreatic cancer cell line BxPC3 after transfection by miR-208 mimic, miR-208 inhibitor and NC. Transwell invasion and scratch assays showed that after overexpressing miR-208, pancreatic cancer cell line BxPC3 exhibited enhanced in vitro migratory and invasive abilities, while after downregulating miR-208 expression, cell migratory and invasive abilities were decreased. Western blotting and quantitative PCR showed that after overexpressing miR-208, expression of E-cadherin, an epithelial cell marker, was decreased and expression of fibronectin and vimentin, interstitial cell markers, was increased in pancreatic cancer cell line BxPC3; however, after inhibiting miR-208, increased E-cadherin expression and decreased fibronectin and vimentin expression were observed in pancreatic cancer cell line BxPC3. After overexpressing miR-208, p-AKT and p-GSK-3β expression was altered by activating AKT/GSK-3β/snail signaling pathway. miR-208 induces epithelial to mesenchymal transition of pancreatic cancer cell line BxPC3 by activating AKT/GSK-3β/snail signaling pathway and thereby promotes cell metastasis and invasion.