Review: The Dynamics of the Nuclear Lamins during the Cell Cycle— Relationship between Structure and Function

The nuclear lamins are members of the intermediate filament (IF) family of proteins. The lamins have an essential role in maintaining nuclear integrity, as do the other IF family members in the cytoplasm. Also like cytoplasmic IFs, the organization of lamins is dynamic. The lamins are found not only at the nuclear periphery but also in the interior of the nucleus, as distinct nucleoplasmic foci and possibly as a network throughout the nucleus. Nuclear processes such as DNA replication may be organized around these structures. In this review, we discuss changes in the structure and organization of the nuclear lamins during the cell cycle and during cell differentiation. These changes are correlated with changes in nuclear structure and function. For example, the interactions of lamins with chromatin and nuclear envelope components occur very early during nuclear assembly following mitosis. During S-phase, the lamins colocalize with markers of DNA replication, and proper lamin organization must be maintained for replication to proceed. When cells differentiate, the expression pattern of lamin isotypes changes. In addition, changes in lamin organization and expression patterns accompany the nuclear alterations observed in transformed cells. These lamin structures may modulate nuclear function in each of these processes.     

Effects of various conditions on the alkaline degradation of d-fructose and d-glucose

Dilute solutions of d-fructose and d-glucose undergo alkaline degradation, and, at temperatures in the range of 30–70°, almost two moles of alkali are consumed per mole of the carbohydrate. The degradation is partly guided by the dielectric constant of the medium; such additives as acetone and urea have specific effects where the reactions are not essentially guided by the medium dielectric. Acetone and urea presumably form complexes with the carbohydrates; this is revealed for the former by the formation of a dark red solution having a spectral band at 320 nm, like that observed earlier in the presence of ethylenediamine.     

Ocular Complications in Renal Transplant Recipients

Twenty-five patients were examined for ocular complaints following renal transplantation. Besides the expected complications of posterior subcapsular cataract and cytomegalovirus retinitis, other findings—such as focal depigmentation of the retinal pigment epithelium, a lack of hypertensive retinopathy, elevated intraocular tensions, microaneurysms, preretinal wrinkling, serous detachments of the retina, hemorrhages and exudates—were observed.A laboratory clue to the onset of cytomegalovirus retinitis was a rapid rise in cytomegalovirus (CMV) antibody titer and a positive CMV plaque count in tissue culture.     

Dynamic signal processing by ribozyme-mediated RNA circuits to control gene expression

Organisms have different circuitries that allow converting signal molecule levels to changes in gene expression. An important challenge in synthetic biology involves the de novo design of RNA modules enabling dynamic signal processing in live cells. This requires a scalable methodology for sensing, transmission, and actuation, which could be assembled into larger signaling networks. Here, we present a biochemical strategy to design RNA-mediated signal transduction cascades able to sense small molecules and small RNAs. We design switchable functional RNA domains by using strand-displacement techniques. We experimentally characterize the molecular mechanism underlying our synthetic RNA signaling cascades, show the ability to regulate gene expression with transduced RNA signals, and describe the signal processing response of our systems to periodic forcing in single live cells. The engineered systems integrate RNA–RNA interaction with available ribozyme and aptamer elements, providing new ways to engineer arbitrary complex gene circuits.     

Isolation and partial purification of an antimicrobial agent from halotolerant alkaliphilic <Emphasis Type="Italic">Streptomyces aburaviensis</Emphasis> strain Kut-8

A halotolerant alkaliphilic actinomycete, Kut-8, was isolated from saline desert of Kutch, Western India. It has been identified as Streptomyces aburaviensis based on the chemotaxonomic characteristics, including cell wall constituents. Kut-8 is Gram-positive having a spiral sporophore with dark green and fluffy spore mass. It was able to grow with 15%, w/v NaCl with optimum being in the range of 5–10%. It grew optimally at pH 9 with slow growth at neutral pH. The cell wall contained l-diaminopimelic acid and no diagnostic sugars. It produced an antibiotic that selectively inhibited the growth of Gram-positive bacteria, with Bacillus subtilis being the most sensitive. Kut-8 secreted the antibiotic optimally during mid-stationary phase (on day 14 of growth in liquid culture). The crude antibiotic metabolites were separated by various solvent systems with hexane–methanol–water giving the best separation. The results of bioautographs revealed the presence of single active compound in the Kut-8 antibiotic filtrate. Partial purification of antibiotic metabolite by charcoal absorption and methanol extraction resulted in enhanced antimicrobial activity by 4.16-fold. The study holds significance as only few salt-tolerant alkaliphilic actinomycetes from saline deserts have been explored and information on their antimicrobial potential is still scarce.     

Improving enzyme characteristics by gene shuffling; application to β-glucosidase

The genes of family 3 β-glucosidase enzymes consist of five distinct regions; the N-terminal residues, an N-terminal catalytic domain, a nonhomologous region, a C-terminal domain of unknown function and the C-terminal residues. The β-glucosidase genes derived from Cellvibrio gilvus (CG) and Agrobacterium tumefaciens (AT) have been subjected to gene deletion, truncation and shuffling. The folding information was found to be distributed unevenly across the different regions based on the gene manipulation results. Chimeric enzymes with improved enzyme characteristics were obtained only by gene shuffling at the C-terminal domain.