Effect of unsaturated fatty acids in growth inhibition of some penicillin-resistant and sensitive bacteria

The growth of two penicillin-resistant Gram-positive bacteria, Bacillus licheniformis (749/C, penicillin G-resistant) and Staphylococcus aureus (metR 18, methicillin-resistant) and one Gram-negative strain, Escherichia coli (cloxacillin-resistant) as well as that of their wild counterparts was inhibited by the long-chain unsaturated fatty acids, linoleic, linolenic and arachidonic acid. The minimum inhibitory concentrations (MIC) of all the fatty acids were found to be 4–6 μg/ml for Staph. aureus (metR 18 & wild), 8–30 μg/ml for B. licheniformis (749/C & wild) and 70–90 μg/ml for E. coli (cloxacillin-resistant & wild). The inhibitory activity increased as the number of double bonds in the fatty acids increased. In most instances the concentrations of fatty acids required to inhibit the growth of the penicillin-resistant strains were lower than that required for their sensitive counterparts. This inhibition of growth in the presence of fatty acids may be due to an increase in permeability of the membrane as evidenced by the measurement of the leakage of 260 nm absorbing material and fluidity.     

Dielectric behavior of DNA--dye complex. II

The dielectric relaxation of native DNA and the effect of aminoacridine dyes, such as acridine orange (AO), proflavine (PF), and ethidium bromide (EB) have been investigated at different molar DNA phosphate (P) to dye (D) ratios in the frequency range 100 Hz–100 kHz. The static dielectric constant was observed to decrease with increasing binding of aminoacridines. This was interpreted as arising from the neutralization of the surface changes of the DNA molecules as a result of dye binding. At any P/D ratio the extent of charge neutralization was greatest for AO and least for the EB–DNA complex. The relaxation time (τ) for dye-bound DNA was greater compared to that for native DNA. This increase in τ was ascribed to the increase in the length of the dye-bound DNA. The maximum value of τ occurred at P/D = 20, 10, and 2 for AO-, PF-, and EB-treated DNA, respectively. The variation of τ at various levels of binding gave a qualitative idea about the conformational changes of DNA due to its binding with the dyes.     

Characterization of the Replication Initiator Orc1/Cdc6 from the Archaeon Picrophilus torridus

Eukaryotic DNA replication is preceded by the assembly of prereplication complexes (pre-RCs) at or very near origins in G₁ phase, which licenses origin firing in S phase. The archaeal DNA replication machinery broadly resembles the eukaryal apparatus, though simpler in form. The eukaryotic replication initiator origin recognition complex (ORC), which serially recruits Cdc6 and other pre-RC proteins, comprises six components, Orc1-6. In archaea, a single gene encodes a protein similar to both the eukaryotic Cdc6 and the Orc1 subunit of the eukaryotic ORC, with most archaea possessing one to three Orc1/Cdc6 orthologs. Genome sequence analysis of the extreme acidophile Picrophilus torridus revealed a single Orc1/Cdc6 (PtOrc1/Cdc6). Biochemical analyses show MBP-tagged PtOrc1/Cdc6 to preferentially bind ORB (origin recognition box) sequences. The protein hydrolyzes ATP in a DNA-independent manner, though DNA inhibits MBP-PtOrc1/Cdc6-mediated ATP hydrolysis. PtOrc1/Cdc6 exists in stable complex with PCNA in Picrophilus extracts, and MBP-PtOrc1/Cdc6 interacts directly with PCNA through a PIP box near its C terminus. Furthermore, PCNA stimulates MBP-PtOrc1/Cdc6-mediated ATP hydrolysis in a DNA-dependent manner. This is the first study reporting a direct interaction between Orc1/Cdc6 and PCNA in archaea. The bacterial initiator DnaA is converted from an active to an inactive form by ATP hydrolysis, a process greatly facilitated by the bacterial ortholog of PCNA, the β subunit of Pol III. The stimulation of PtOrc1/Cdc6-mediated ATP hydrolysis by PCNA and the conservation of PCNA-interacting protein motifs in several archaeal PCNAs suggest the possibility of a similar mechanism of regulation existing in archaea. This mechanism may involve other yet to be identified archaeal proteins.     

Functional asymmetry in the face.

The possible existence of one-sided dominance in the face, similar to the phenomena of handedness and footedness, has been investigated by studying smiling pattern, movements of the angles of mouth, winking, platysma contraction, raising and everting the upper lip with dilatation of the nostril, and vertical wrinkling of the forehead, on 300 right-handed and 30 left-handed persons. The conclusions are as follows: 1. The large majority of persons investigated do not use the two sides of face equally. 2. Facial ambilaterality is a rare feature. 3. There is no clear-cut correlation between handedness and the dominant side of the face. 4. The greater percentage (58.66%) of right-handed persons show a left-sided smile and find it more convenient to perform almost all exercises with the left side of the face. A still greater percentage (73.33%) of left-handed persons shows a right-sided smile and a better performance of all exercises with the right side of the face. The contralateral relationship of handedness to the dominant side of the face is significant in the right-handed and more so, in the left-handed persons.     

Cloning of the rat insulin-like growth factor binding protein-1 gene and analysis of its 5' promoter region.

To understand specific mechanisms involved in the regulation of insulin-like growth factor binding protein-1 (IGFBP-1), an important modulator of IGF bioactivity, we cloned the rat IGFBP-1 gene and sequenced a 1.5 kb Sph1-Sph1 fragment containing 1110 bases upstream from the translation start site. Computer analysis reveals the presence of ATA, CACCC, and CCAAT elements, and putative homeodomain, AP-1, insulin and glucocorticoid response elements in the 5' promoter. Primer extension and ribonuclease protection studies reveal a single cap site in RNA from rat hepatoma cells and both control and diabetic rat liver.     

Isolation and Characterization of Arsenic-Resistant Bacteria from Contaminated Water-Bodies in West Bengal,India

Bengal Basin is known for severe arsenic contamination. In the present study, we have isolated six bacteria from the arsenic contaminated surface water of Bengal Basin. 16S rDNA sequence analysis identified them as Microbacterium oleivorans, Acinetobacter soli, Acinetobacter venetianus, Acinetobacter junii, Acinetobacter baumannii, Acinetobacter calcoaceticus. All the isolates possess arsenic accumulation potential and high molecular weight plasmid (>10 kb). PCR amplification indicated the presence of arsenic-resistance genes (arsB and aoxB) either in the genome or plasmid or in both in the isolated bacteria (except in Acinetobacter venetianus). Exposure to arsenic affected bacterial growth and induced alteration in cytoplasmic membrane integrity.     

A Conceptual Cortical Surface Atlas

Volumetric, slice-based, 3-D atlases are invaluable tools for understanding complex cortical convolutions. We present a simple scheme to convert a slice-based atlas to a conceptual surface atlas that is easier to visualize and understand. The key idea is to unfold each slice into a one-dimensional vector, and concatenate a succession of these vectors – while maintaining as much spatial contiguity as possible – into a 2-D matrix. We illustrate our methodology using a coronal slice-based atlas of the Rhesus Monkey cortex. The conceptual surface-based atlases provide a useful complement to slice-based atlases for the purposes of indexing and browsing.     

Shape Covariation (or the Lack Thereof) Between Vertebrae and Other Skeletal Traits in Felids: The Whole is Not Always Greater than the Sum of Parts

Within carnivorans, cats show comparatively little disparity in overall morphology, with species differing mainly in body size. However, detailed shape analyses of individual osteological structures, such as limbs or skulls, have shown that felids display significant morphological differences that correlate with their observed ecological and behavioural ranges. Recently, these shape analyses have been extended to the felid axial skeleton. Results demonstrate a functionally-partitioned vertebral column, with regions varying greatly in level of correlation between shape and ecology. Moreover, a clear distinction is evident between a phylogenetically-constrained neck region and a selection-responsive posterior spine. Here, we test whether this regionalisation of function reflected in vertebral column shape is also translated into varying levels of phenotypic integration between this structure and most other skeletal elements. We accomplish this comparison by performing pairwise tests of integration between vertebral and other osteological units, quantified with 3D geometric morphometric data and analysed both with and without phylogenetic correction. To our knowledge, this is the first study to test for integration across a comprehensive sample of whole-skeleton elements. Our results show that, prior to corrections, strong covariation is present between vertebrae across the vertebral column and all other elements, with the exception of the femur. However, most of these significant correlations disappear after correcting for phylogeny, which is a significant influence on cranial and limb morphology of felids and other carnivorans. Our results thus suggest that the vertebral column of cats displays relative independence from other skeletal elements and may represent several distinct evolutionary morphological modules.