Differentiation of 2-cell and 8-cell mouse embryos arrested by cytoskeletal inhibitors

Mouse embryos at the 2-cell stage were cultured in the presence of cytochalasin B (CB), cytochalasin D (CD), colchicine (COL) or colcemid (COM) for up to 72 h. Cleavage was arrested in the 2-cell and 8-cell embryos cultured in CB or CD but the blastomeres continued to differentiate, since chromosome replication occurred in the blastomeres at approximately the same time as control embryos underwent cleavage; an increase in the incorporation of [³H]uridine into RNA was also detected. Furthermore, the cleavage-arrested embryos acquired the necessary information to undergo morphogenesis; these embryos when explanted to fresh medium after 48 h culture in CB or CD underwent compaction within 15–60 min and started to cavitate to produce trophoblastic vesicles within 5–6 h at the same time as when the control embryos were undergoing compaction and beginning to form blastocoelic cavities. In contrast, the embryos arrested in the presence of COM or COL showed none of these differentiative, biochemical or morphogenetic changes. Hence, differentiation of blastomeres and morphogenesis is apparently coupled with nuclear divisions and the information does not reside within the blastomeres at the 2-cell or 8-cell stage. The trophoblastic vesicles produced after cleavage arrest subsequently gave rise to only trophoblast giant cells and no embryonic derivatives were detected.     

Anthropological studies among Libyans. Erythrocyte genetic factors,serum haptoglobin phenotypes and anthropometry

Anthropological studies were done on 1276 Libyans from the Mediterranean cities of Tripoli and Benghazi, and from Sabha southward in The Sahara. The incidences of hemoglobin (Hb)-S and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency were low in the coastal areas and significantly high in Sabha. Hb-C occurred sporadically in Tripoli and Sabha, and was absent from Benghazi in the east. One case of Hb-J Benghazi was noted. There were no significant differences in the ABO blood group and Rh₀ (D) type distributions in the three localities. G-6-PD gene Gd^A frequency was significantly high in Sabha. The lowest value of 6-phosphogluconate dehydrogenase (6-PGD) gene PGD^A frequency and highest value of the gene PGD^C were in Sabha. Adenylate kinase (AK) gene AK² was only detectable in Tripoli. Acid phosphatase (AP) gene P^a frequency in Sabha was more than twice that in Tripoli and Benghazi, while P^c was distinctly lower in Sabha than in the northern cities. Haptoglobin gene Hp¹ frequency was almost identical in all areas. Anthropometric measurements revealed overall homogeneity of the three samples, closer similarity in the coastal region to adjacent North African populations, and Negroid influence in the Saharan Libyans. Anthropometry substantiated findings from blood markers.     

Elevated nutrient inputs to marshes differentially impact carbon and nitrogen cycling in two northern Gulf of Mexico saltmarsh plants

Peatlands have accumulated vast quantities of organic carbon over thousands of years but it is unclear how these sensitive ecosystems will respond to future climate change. If emissions of methane from peatlands increase, then they may contribute increasingly towards climatic warming due to the higher greenhouse warming potential of this gas. We investigated the radiocarbon concentration of methane emissions from a temperate bog over 1.5 years, which we supported with measurements of the surface flux of methane and carbon dioxide. The radiocarbon content of methane emissions varied greatly, from modern (i.e. fixed from the atmosphere within recent decades) to ~ 1400 years BP. Flux rates of methane were spatially and temporally highly variable. A vegetation clipping experiment showed that plants had a great influence on the carbon isotope composition and flux of methane emitted from the peat surface, consistent with earlier studies showing the key role of plants in peatland methane emissions. When plants were absent, emission rates were 70–94% lower and the radiocarbon age of methane emissions was much younger and less variable. Our radiocarbon measurements show that at this peatland, plant-associated methane emissions contain carbon originally fixed from the atmosphere up to hundreds of years earlier, consistent with a contribution from plant mediated transport of methane sourced from sub-surface layers.

     

Bovine serum albumin/gold nanoparticles as a drug delivery system for Curcumin: experimental and computational studies

Abstract

Communicated by Ramaswamy H. Sarma     

Hepatoprotective Effect of Manganese Chloride Against CCl4-Induced Liver Injury in Rats

The aim of the present study is to evaluate the protective effect of manganese chloride against carbon tetrachloride (CCl₄)-induced liver injury in rats. Manganese chloride (0.001, 0.01, 0.05 and 0.1 g/kg bw) was administered intragastrically for 28 consecutive days to male CCl₄-treated rats. The hepatoprotective activity was assessed using various biochemical parameters such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), γ-glutamyltransferase (GGT) and superoxide dismutase (SOD). Histopathological changes in the liver of different groups were also studied. Administration of CCl₄ increased the serum ALT, AST, ALP and GGT but decreased SOD levels in rats. Treatment with manganese chloride significantly attenuated these changes to nearly normal levels. The animals treated with manganese chloride have shown decreased necrotic zones and hepatocellular degeneration when compared to the liver exposed to CCl₄ intoxication alone. Thus, the histopathalogical studies also supported the protective effect of manganese chloride. Therefore, the results of this study suggest that manganese chloride exerts hepatoprotection via promoting antioxidative properties against CCl₄-induced oxidative liver damage.     

DNA methylation dynamics during the mammalian life cycle

DNA methylation is dynamically remodelled during the mammalian life cycle through distinct phases of reprogramming and de novo methylation. These events enable the acquisition of cellular potential followed by the maintenance of lineage-restricted cell identity, respectively, a process that defines the life cycle through successive generations. DNA methylation contributes to the epigenetic regulation of many key developmental processes including genomic imprinting, X-inactivation, genome stability and gene regulation. Emerging sequencing technologies have led to recent insights into the dynamic distribution of DNA methylation during development and the role of this epigenetic mark within distinct genomic contexts, such as at promoters, exons or imprinted control regions. Additionally, there is a better understanding of the mechanistic basis of DNA demethylation during epigenetic reprogramming in primordial germ cells and during pre-implantation development. Here, we discuss our current understanding of the developmental roles and dynamics of this key epigenetic system.     

Diurnal patterns of gas‐exchange and metabolic pools in tundra plants during three phases of the arctic growing season

Arctic tundra plant communities are subject to a short growing season that is the primary period in which carbon is sequestered for growth and survival. This period is often characterized by 24‐h photoperiods for several months a year. To compensate for the short growing season tundra plants may extend their carbon uptake capacity on a diurnal basis, but whether this is true remains unknown. Here, we examined in situ diurnal patterns of physiological activity and foliar metabolites during the early, mid, and late growing season in seven arctic species under light‐saturated conditions. We found clear diurnal patterns in photosynthesis and respiration, with midday peaks and midnight lulls indicative of circadian regulation. Diurnal patterns in foliar metabolite concentrations were less distinct between the species and across seasons, suggesting that metabolic pools are likely governed by proximate external factors. This understanding of diurnal physiology will also enhance the parameterization of process‐based models, which will aid in better predicting future carbon dynamics for the tundra. This becomes even more critical considering the rapid changes that are occurring circumpolarly that are altering plant community structure, function, and ultimately regional and global carbon budgets.     

In Vivo Differences between Two Optical Isomers of Radioiodinated o-iodo-trans-decalinvesamicol for Use as a Radioligand for the Vesicular Acetylcholine Transporter

Purpose

To develop a superior VAChT imaging probe for SPECT, radiolabeled (-)-OIDV and (+)-OIDV were isolated and investigated for differences in their binding affinity and selectivity to VAChT, as well as their in vivo activities.

Procedures

Radioiodinated o-iodo-trans-decalinvesamicol ([¹²⁵I]OIDV) has a high binding affinity for vesicular acetylcholine transporter (VAChT) both in vitro and in vivo. Racemic [¹²⁵I]OIDV was separated into its two optical isomers (-)-[¹²⁵I]OIDV and (+)-[¹²⁵I]OIDV by HPLC. To investigate VAChT binding affinity (Ki) of two OIDV isomers, in vitro binding assays were performed. In vivo biodistribution study of each [¹²⁵I]OIDV isomer in blood, brain regions and major organs of rats was performed at 2,30 and 60 min post-injection. In vivo blocking study were performed to reveal the binding selectivity of two [¹²⁵I]OIDV isomers to VAChT in vivo. Ex vivo autoradiography were performed to reveal the regional brain distribution of two [¹²⁵I]OIDV isomers and (-)-[¹²³I]OIDV for SPECT at 60 min postinjection.

Results

VAChT binding affinity (Ki) of (-)-[¹²⁵I]OIDV and (+)-[¹²⁵I]OIDV was 22.1 nM and 79.0 nM, respectively. At 2 min post-injection, accumulation of (-)-[¹²⁵I]OIDV was the same as that of (+)-[¹²⁵I]OIDV. However, (+)-[¹²⁵I]OIDV clearance from the brain was faster than (-)-[¹²⁵I]OIDV. At 30 min post-injection, accumulation of (-)-[¹²⁵I]OIDV (0.62 ± 0.10%ID/g) was higher than (+)-[¹²⁵I]OIDV (0.46 ± 0.07%ID/g) in the cortex. Inhibition of OIDV binding showed that (-)-[¹²⁵I]OIDV was selectively accumulated in regions known to express VAChT in the rat brain, and ex vivo autoradiography further confirmed these results showing similar accumulation of (-)-[¹²⁵I]OIDV in these regions. Furthermore, (-)-[¹²³I]OIDV for SPECT showed the same regional brain distribution as (-)-[¹²⁵I]OIDV.

Conclusion

These results suggest that radioiodinated (-)-OIDV may be a potentially useful tool for studying presynaptic cholinergic neurons in the brain.     

Parallel Mapping of Antibiotic Resistance Alleles in Escherichia coli

Chemical genomics expands our understanding of microbial tolerance to inhibitory chemicals, but its scope is often limited by the throughput of genome-scale library construction and genotype-phenotype mapping. Here we report a method for rapid, parallel, and deep characterization of the response to antibiotics in Escherichia coli using a barcoded genome-scale library, next-generation sequencing, and streamlined bioinformatics software. The method provides quantitative growth data (over 200,000 measurements) and identifies contributing antimicrobial resistance and susceptibility alleles. Using multivariate analysis, we also find that subtle differences in the population responses resonate across multiple levels of functional hierarchy. Finally, we use machine learning to identify a unique allelic and proteomic fingerprint for each antibiotic. The method can be broadly applied to tolerance for any chemical from toxic metabolites to next-generation biofuels and antibiotics.