Biotin-decorated anti-cancer nucleotide theranostic conjugate of human serum albumin: Where the seed meets the soil?

Human serum albumin is playing an increasing role as a drug carrier in clinical settings. Biotin molecules are often used as suitable tags in targeted anti-tumor drug delivery systems. We report on the synthesis and properties of a new multimodal theranostic conjugate based on an anti-cancer fluorinated nucleotide conjugated with a biotinylated dual-labeled albumin. Interestingly, in vitro and in vivo study revealed stronger anti-tumor activity of the non-tagged theranostic conjugate than that of the biotin-tagged conjugate, which can be explained by decreased binding of the biotin-tagged conjugate to cellular receptors. Our study sheds light on the importance of site-specific albumin modification for the design of albumin-based drugs with desirable pharmaceutical properties.     

Antimony (V) Complex Halides: Lead‐Free Perovskite‐Like Materials for Hybrid Solar Cells

Using bromoantimonate (V) (N‐EtPy)[SbBr₆] as an example, it is demonstrated that ABX₆ compounds can form perovskite‐like 3D crystalline frameworks with short interhalide contacts, enabling advanced optoelectronic characteristics of these materials. The designed compound shows an impressive performance in planar junction solar cells delivering external quantum efficiency of ≈80% and power conversion efficiency of ≈4%, thus being comparable with the conventional perovskite material MAPbBr₃. The discovery of the first perovskite‐like compound ABX₆ exhibiting good photovoltaic performance opens wide opportunities for rational design of novel perovskite‐like semiconductor materials for advanced electronic and photovoltaic applications.     

Characterization of an Adenovirus Vector Containing a Heterologous Peptide Epitope in the HI Loop of the Fiber Knob

The utility of the present generation of recombinant adenovirus vectors for gene therapy applications could potentially be improved by designing targeted vectors capable of gene delivery to selected cell types in vivo. In order to achieve such targeting, we are investigating the possibilities of incorporation of ligands in the adenovirus fiber protein, which mediates primary binding of adenovirus to its cell surface receptor. Based on the proposed structure of the cell-binding domain of the fiber, we hypothesized that the HI loop of the fiber knob can be utilized as a convenient locale for incorporation of heterologous ligands. In this study, we utilized recombinant fiber proteins expressed in baculovirus-infected insect cells to demonstrate that the incorporation of the FLAG octapeptide into the HI loop does not ablate fiber trimerization and does not disturb formation of the cell-binding site localized in the knob. We then generated a recombinant adenovirus containing this modified fiber and showed that the short peptide sequence engineered in the knob is compatible with the biological functions of the fiber. In addition, by using a ligand-specific antibody, we have shown that the peptide incorporated into the knob remains available for binding in the context of mature virions containing modified fibers. These findings suggest that heterologous ligands can be incorporated into the HI loop of the fiber knob and that this locale possesses properties consistent with its employment in adenovirus retargeting strategies.Recombinant adenovirus vectors have found wide employment for a number of gene therapy applications (22, 36, 40). This fact has derived principally from the high levels of gene transfer achievable with this vector approach both in vitro and in vivo. Indeed, recombinant adenovirus vectors are distinguished from other available systems by their unique ability to accomplish in situ gene delivery to differentiated target cells in a variety of organ contexts (5, 6, 9, 10, 12, 21, 26, 28, 30, 32). Despite this property, specific aspects of the adenovirus biology have prevented the full realization of the potential of such vectors. In this regard, the broad tropism profile of the parent virus for cells of diverse tissues potentially allows unrestricted gene delivery. Thus, for the many gene therapy applications requiring targeted, cell-specific gene delivery, the promiscuous tropism of the adenovirus vector represents a confounding factor. Based on this concept, strategies to modify the native tropism of adenovirus have been developed to allow the derivation of vectors capable of targeted gene delivery.Strategies to achieve this end are directed at modifying specific steps in the adenovirus infection pathway. Adenoviruses of serotypes 2 and 5 normally achieve initial recognition and binding to target cells by means of interactions between the carboxy-terminal knob domain of the fiber protein and the primary receptor (4, 19, 39). After binding, RGD motifs in the penton base interact with cellular integrins of the α_Vβ₃ and α_Vβ₅ types (1–3, 43, 44). This interaction triggers cellular internalization whereby the virions achieve localization within the endosome. Acidification of the endosome elicits conformational changes in capsid proteins, allowing their interaction with the endosome membrane in a manner that achieves vesicle disruption and particle escape (41). Following endosomolysis, the virion translocates to the nucleus, where the subsequent steps of the viral life cycle occur. This understanding of the key role played by capsid proteins in the viral infectious pathway has suggested strategies to alter this process via modifications of these proteins.In this regard, genetic retargeting of adenovirus vectors via modification of viral genes encoding coat proteins, if successful, offers a simple way to achieve a significant improvement in the present generation of these gene-delivery vehicles. To this end, several groups have reported genetic modifications to the knob domain of adenovirus fiber protein and incorporation of such chimeric fibers into virions. For instance, Stevenson et al. (37) and Krasnykh et al. (25) reported successful generation of adenovirus type 5 (Ad5) virions containing fibers consisting of the tail and shaft domains of Ad5 fiber and the knob domain of Ad3, respectively. In addition, Michael et al. (31) demonstrated the incorporation of the gastrin-releasing peptide into the carboxy terminus of recombinant Ad5 fiber. This finding was extended by Legrand et al. (30a), who achieved rescue of recombinant adenovirus vectors containing such fibers. Another report published by Wickham et al. (45) described the generation of recombinant virus containing fibers with carboxy-terminal polylysine sequences. These studies have established key feasibility issues with respect to this genetic approach but have also demonstrated a number of potentially limiting factors.Of note, all the modifications of adenovirus fiber reported so far were directed towards the carboxy terminus of the protein. In addition, these efforts were initiated without prior knowledge of the three-dimensional (3D) structure of the fiber knob. Thus, the employment of the carboxy terminus of the fiber represented a choice of convenience without consideration of the knob tertiary structure. Clearly, 3D structural information has important bearing upon the placement of heterologous protein sequences within the knob for targeting purposes. Such localization of targeting ligands would ideally be achieved in such a manner as to allow their surface presentation and to minimally perturb the fiber quaternary structure. Thus, the recent crystallization of the fiber knob by Xia et al. (47, 48) has provided a level of structural resolution potentially allowing such a rational modification of the fiber protein. According to the proposed 3D model of the knob (Fig. ​(Fig.1),1), the HI loop possesses a number of features which predict its utility as an alternative site for ligand incorporation. Specifically, the HI loop does not contribute to intramolecular interactions in the knob. Therefore, incorporation of additional protein sequence should not affect the trimerization of the fiber. In addition, the loop consists mostly of hydrophilic amino acid residues and is exposed outside the knob. It thus potentially demonstrates a high degree of flexibility, creating an optimal environment for ligand incorporation. Furthermore, the lengths of HI loops vary significantly in knobs of different adenovirus serotypes. This fact suggests that alterations of the original structure of the loop, such as insertions and deletions, should be compatible with the correct folding of the entire knob domain. Finally, the HI loop is not involved in the formation of the putative cell-binding site localized in the knob. Open in a separate windowFIG. 13D model of the Ad5 fiber knob. The trimer forms a propeller-like structure when it is viewed along the threefold-symmetry axis from above. The HI loop, exposed outside the knob, connects the β-strands H and I, which are involved in the formation of the cell-binding site. (Reproduced from reference 47 by permission.)Based on these considerations, we endeavored to develop a novel approach to modify the adenovirus fiber protein by employing the HI loop of the knob for this purpose. We show in this report that it is possible to incorporate heterologous amino acid sequences into the HI loop without affecting the correct folding of the fiber polypeptide and its biological functions. Further, our results suggest that this locale may offer advantages for strategies designed to achieve tropism modification based on genetic alteration of capsid proteins.     

<Emphasis Type="Italic">Thermosulfurimonas marina</Emphasis> sp. nov., an Autotrophic Sulfur-Disproportionating and Nitrate-Reducing Bacterium Isolated from a Shallow-Sea Hydrothermal Vent

A thermophilic, anaerobic, chemolithoautotrophic bacterium (strain SU872^T) was isolated from a shallow-sea hydrothermal vent at Kunashir Island. The cells were motile, gram-negative, oval or rodshaped 0.5?0.6 μm thick and 1.5?2.0 μm long, occurring singly or in pairs. Strain SU872^T grew at 50 to 79°C (optimum at 74°C), pH from 5.0 to 8.0 (optimum at 6.7?7.0), and NaCl concentration of 1.5–4.5%. Strain SU872^T was able to grow by disproportionation of elemental sulfur, thiosulfate, or sulfite, with CO₂/HCO₃^? as the sole carbon source. Growth was enhanced in the presence of ferrihydrite (poorly crystalline Fe(III) oxide) as as a sulfide-scavenging agent. Sulfate was not used as an electron acceptor. Growth also occurred with elemental sulfur, thiosulfate, or sulfite (but not sulfide) as electron donors and nitrate as an electron acceptor, with production of sulfate and ammonium. Analysis of the 16S rRNA gene sequence revealed 97.8% similarity between strain SU872^T and the type strain Thermosulfurimonas dismutans S95^T (phylum Thermodesulfobacteria). According to the results of DNA–DNA hybridization, the similarity of genomic DNA of the strains SU872^T and T. dismutans S95^T was 48%. Based on its phenotypic characteristics and the results of phylogenetic analysis, it is proposed to assign the isolate to a new species of the genus Thermosulfurimonas,—Thermosulfurimonas marina sp. nov., with the type strain SU872^T (=DSM 104922^T, =VKM B-3177^T, =UNIQEM SU872^T).     

Effects of mitochondrial antioxidant SkQ1 on biochemical and behavioral parameters in a Parkinsonism model in mice

According to one hypothesis, Parkinson’s disease pathogenesis is largely caused by dopamine catabolism that is catalyzed on mitochondrial membranes by monoamine oxidase. Reactive oxygen species are formed as a byproduct of these reactions, which can lead to mitochondrial damage followed by cell degeneration and death. In this study, we investigated the effects of administration of the mitochondrial antioxidant SkQ1 on biochemical, immunohistochemical, and behavioral parameters in a Parkinson-like condition caused by protoxin MPTP injections in C57BL/6 mice. SkQ1 administration increased dopamine quantity and decreased signs of sensory-motor deficiency as well as destruction of dopaminergic neurons in the substantia nigra and ventral tegmental area in mice with the Parkinson-like condition.     

早期形态发生:一种解决贻贝科(软体动物门:双壳纲)分类、系统发育和进化问题的方法

作者对贻贝科贝类的幼虫和幼贝期发育阶段形态结构的出现和变化顺序进行了研究,其约60个不同分类单元的个体发生可归纳为4种形态发生类型或模式。主要对3个形态发生区域的阶段形态结构的起源、发育变化和同源性做了研究。其一,即中央区域,开始形成于前双壳Ⅰ期(PD-Ⅰ),在某个分类单元它可以在前双壳Ⅱ期(PD-Ⅱ)和幼贝期(N)形成,而在其它分类单元则在前双壳Ⅱ期、幼贝期和双壳期(D)形成;第二区域,即背部后区,在幼贝期出现;第三区域,即背部前区,出现于双壳期。双壳期背部后区在某个分类单元起源于幼贝期的形态构造,在其它分类单元则可能起源于双壳期的形态构造。与在贻贝分类学上应用的成体特征相比,早期发育阶段中央和背部后区的形态结构显示出很明显的发育顺序或特征变化规律。根据以前人们熟知而尚未应用到分类和系统发育研究中的早期发育阶段形态特征,作者重新修订了Soot-Ryen的现生贻贝科种上阶元分类系统,重新提出了科内系统发育关系。修订的分类系统表明,Scarlato and Starobogatov(1984)提出的贻贝科各亚科由偏顶蛤亚科开始,沿4条系统发育路线演化发展,对应其早期发育阶段的4类形态发生类型或模式。     

Novel Primers Reveal Wider Diversity among Marine Aerobic Anoxygenic Phototrophs

Aerobic anoxygenic phototrophic bacteria (AAnPs) were previously proposed to account for up to 11% of marine bacterioplankton and to potentially have great ecological importance in the world's oceans. Our data show that previously used primers based on the M subunit of anoxygenic photosynthetic reaction center genes (pufM) do not comprehensively identify the diversity of AAnPs in the ocean. We have designed and tested a new set of pufM-specific primers and revealed several new AAnP variants in environmental DNA samples and genomic libraries.     

Protein S3 fragments neighboring mRNA during elongation and termination of translation on the human ribosome

Protein S3 fragments were determined that crosslink to modified mRNA analogues in positions +5 to +12 relative to the first nucleotide in the P-site bound codon in model complexes mimicking states of ribosomes at the elongation and translation termination steps. The mRNA analogues contained a Phe codon UUU/UUC at the 5′-termini that could predetermine the position of the tRNA^Phe on the ribosome by the P-site binding and perfluorophenylazidobenzoyl group at a nucleotide in various positions 3′ of the UUU/UUC codon. The crosslinked S3 protein was isolated from 80S ribosomal complexes irradiated with mild UV light and subjected to cyanogen bromide—induced cleavage at methionine residues with subsequent identification of the crosslinked oligopeptides. An analysis of the positions of modified oligopeptides resulting from the cleavage showed that, in dependence on the positions of modified nucleotides in the mRNA analogue, the crosslinking sites were found in the N-terminal half of the protein (fragment 2–217) and/or in the C-terminal fragment 190–236; the latter reflects a new peculiarity in the structure of the mRNA binding center in the ribosome, unknown to date. The results of crosslinking did not depend on the type of A-site codon or on the presence of translation termination factor eRF1.