Genomics Analysis of Replicative Helicase DnaB Sequences in Proteobacteria.

Replicative Helicase DnaB interacts with DnaA, DnaC, DnaG, and DNA polymerase III to commence replication, increase the movement rate of the replication fork, and to assemble part of the primosome. The formation of the replication fork is limited by the ability to load DnaB to the DNA, thus DnaB has shown to be vital to a large extent. In the absence of DnaB, the replication fork is not maintained and in a state of inactivity the replication fork degrades and collapses. To further understand importance of this enzyme from an evolutionary perspective, a genomic analysis DnaB protein sequences, chosen from five Proteobacteria subclasses was performed. Our analysis indicates that, DnaB replicative helicases of Alphaproteobacteria and Epsilonproteobacteria have diverged at an earlier stage from Betaproteobacteria, Deltaproteobacteria and Gammaproteobacteria as well as from one another. Our results were further supported, when we reanalyzed and reconstructed the phylogenetic tree after the inclusion of sequences from Actinobacteria and Firmicute phylum. In addition, Betaproteobacteria, Deltaproteobacteria, and Gammaproteobacteria appear to share a closer common ancestor than from the other two subclasses. The Dot-plot analysis indicated that, the region between amino acid residues 320 to 400 was strongly conserved among all five subclasses.

Attenuation of Hemodynamic Response to Laryngoscopy and Endotracheal Intubation with Pre Induction IV Fentanyl Versus Combination of IV Fentanyl and Sub Lingual Nitroglycerin Spray.

INTRODUCTION: Endotracheal intubation is one of the most invasive stimuli in anesthesia and it's often accompanied by a hemodynamic pressor response. The purpose of this study was to investigate the efficacy of a single pre-induction 2 µg/kg bolus injection of fentanyl followed by two puffs of nitroglycerin sub lingual spray (400 µg /spray) with a thiopentone/suxamethonium sequence in the attenuation of the hemodynamic response to endotracheal intubation in normotensive patients. MATERIAL AND METHODS: The study consisted of 80 randomly selected ASA physical status I/II male/female adults who were aged between 18 through 60 years and scheduled for elective surgery. Group I received a single 2 µg/kg IV bolus of fentanyl diluted to 5 ml with normal saline 5 min prior to laryngoscopy followed by two puffs of nitroglycerin sub lingual spray (400 µg/spray) 2 minutes prior to intubation (n=40). Group II received a single 2 µg/kg IV bolus of fentanyl diluted to 5 ml with normal saline 5 min prior to laryngoscopy (n=40). Heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure and rate pressure product were compared to basal values at pre-induction, induction, intubation and post-intubation as well as at time increments of 1, 3, 5, 7 and 10 min. RESULTS: Fentanyl combined with nitroglycerin did not attenuate hemodynamic pressor responses more than fentanyl alone. Increases of HR (7.9%), DBP (4.0%), MAP (3.6%) and RPP (6.0%) along with attenuation of SBP (2.7%) were observed in the fentanyl-nitroglycerin group as compared to the equivalent control measured values. CONCLUSIONS: A single pre-induction bolus injection of fentanyl followed by two puffs of nitroglycerin sub lingual spray in a thiopentone/suxamethonium anesthetic sequence neither successfully attenuates nor successfully suppresses the hemodynamic pressor response more effectively than fentanyl alone in normotensive patients resulting from endotracheal intubation.

A comparative analysis of three classes of bacterial non-specific Acid phosphatases and archaeal phosphoesterases: evolutionary perspective.

INTRODUCTION: Bacterial nonspecific acid phosphohydrolases (NSAPs) or phosphatases are group of enzymes secreted as soluble periplasmic proteins or retained as membrane bound lipoproteins that are usually able to dephosphorylate a broad array of structurally unrelated organic phosphoesters (nucleotides, sugar phosphates, phytic acid etc.) to acquire inorganic phosphate (Pi) and organic byproducts. They exhibit optimal catalytic activity at acidic to neutral pH values. On the basis of amino acid sequence relatedness, phosphatase are grouped into different molecular families namely Class A, Class B and Class C acid phosphatase respectively. RESULTS AND DISCUSSION: In this article out of thirty three sequences, twenty six belonging to each of the three classes of bacterial acid phosphatase and seven belonging to archaeal phosphoesterases were analyzed using various tools of bioinformatics. Phylogenetic analysis, dot plot comparisons and motif analysis were done to identify a number of similarities and differences between three classes of bacterial acid phosphatases and archaeal phosphoesterases. In this research we have attempted to decipher evolutionary relationship between three classes of bacterial acid phosphatase and archaeal phosphoesterases using bioinformatics approach.

Latent inhibition in the honey bee, Apis mellifera: Is it a unitary phenomenon?

Latent inhibition refers to learning that some stimuli are not signals of important events. It has been widely studied in vertebrates, but it has been substantially less well studied in invertebrates. We present an investigation into latent inhibition in the honey bee (Apis mellifera) using a proboscis extension response conditioning procedure that involved 'preexposure' of an odor without reinforcement prior to appetitive conditioning. A significant latent inhibition effect, measured in terms of a reduction in acquisition performance to the preexposed odor, was observed after 8 unreinforced presentations, and the effect continued to increase in strength up to 30 presentations. We also observed that memories formed for the preexposed odor lasted at least 24 h. Further manipulation of interstimulus interval and the visual conditioning context partially attenuated the effect. The latter results indicate that latent inhibition in honey bees may not be a unitary phenomenon. Two different mechanisms may be required, in which one mechanism is dependent on the visual context and the second is not.

Vasopressor choice for hypotension in elective Cesarean section: ephedrine or phenylephrine?

INTRODUCTION: Hypotensive episodes are a common complication of spinal anesthesia during Cesarean section. The purpose of this study was to compare the effectiveness and the side effects of vasopressors, ephedrine and phenylephrine, administered for hypotension during elective Cesarean section under spinal anesthesia. MATERIAL AND METHODS: The study consisted of 100 selected ASA I/II females scheduled for elective Cesarean section under spinal anesthesia. Each patient was randomly assigned to one of the two double-blind study groups. Group E received 1 ml ephedrine (5 mg/ml) with normal saline if hypotension was present (n=50). Group P received 1 ml phenylephrine (100 µg/ml) with normal saline if hypotension developed (n=50). Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP) were compared within and between groups to basal levels at time increments of 0, 2, 4, 6, 8, 10, 15, 20, 25, 30, 45, and 60 min from start of surgery. Incidence of side effects and neonatal outcomes were studied between groups. RESULTS: All patients required vasopressor therapy for hypotension. Administration of phenylephrine was associated with significant drop in HR. Changes in SBP, DBP, and MAP were similar in both groups for most observed times. The incidences of nausea/vomiting and tachycardia were significantly higher in the ephedrine group. CONCLUSIONS: Phenylephrine and ephedrine are acceptable choices to combat maternal hypotension related to spinal anesthesia in elective Cesarean section. Complications of intra-operative nausea and vomiting, tachycardia and bradycardia should be considered when choosing a vasopressor, suggesting phenylephrine may be more appropriate when considering maternal well-being.

The linkage between reverse gyrase and hyperthermophiles: a review of their invariable association.

With the discovery of reverse gyrase in 1972, from Yellowstone National Park, isolated from Sulfolobus acidocaldarius, it has been speculated as to why reverse gyrase can be found in all hyperthermophiles and just what exactly its role is in hyperthermophilic organisms. Hyperthermophiles have been defined as organisms with an optimal growth temperature of above 85 degrees C. Reverse gyrase is responsible for the introduction of positive supercoils into closed circular DNA. This review of reverse gyrase in hyperthermophilic microorganisms summarizes the last two decades of research performed on hyperthermophiles and reverse gyrase in an effort to provide an up to date synopsis of their invariable association. From the data gathered for this review it is reasonable to hypothesize that reverse gyrase is closely tied to hyperthermophilic life.

Significance of cellular senescence in aging and cancer.

Cellular senescence is a mechanism that induces an irreversible growth arrest in all somatic cells. Senescent cells are metabolically active but lack the capacity to replicate. Evolutionary theories suggest that cellular senescence is related to the organismal decline occurring in aging organisms. Also, such theories describe senescence as an antagonistically pleiotropic process that can have beneficial or detrimental effect on the organism. Cellular senescence is believed to be involved in the cellular changes observed as aging progresses. Accumulation of senescent cells appears to occur widely as the organism ages. Furthermore, senescence is a key element of the tumor suppressor pathways. Therefore, it is part of the natural barrier against the uncontrolled proliferation observed in cellular development of malignancies in multicellular organisms. Activation of the senescence process guarantees a limited number of cellular replications. The genetic network led by p53 is responsible for activation of senescence in response to DNA damage and genomic instability that could lead to cancer. A better comprehension of the genetic networks that control the cell cycle and induce senescence is important to analyze the association of senescence to longevity and diseases related to aging. For these reasons, experimental research both in vitro and in vivo aims to develop anticancer therapies based on senescence activation. The last decade of research on role and function of senescence in aging and cancer are discussed in this paper.

Behavioral genomics of honeybee foraging and nest defense.

The honeybee has been the most important insect species for study of social behavior. The recently released draft genomic sequence for the bee will accelerate honeybee behavioral genetics. Although we lack sufficient tools to manipulate this genome easily, quantitative trait loci (QTLs) that influence natural variation in behavior have been identified and tested for their effects on correlated behavioral traits. We review what is known about the genetics and physiology of two behavioral traits in honeybees, foraging specialization (pollen versus nectar), and defensive behavior, and present evidence that map-based cloning of genes is more feasible in the bee than in other metazoans. We also present bioinformatic analyses of candidate genes within QTL confidence intervals (CIs). The high recombination rate of the bee made it possible to narrow the search to regions containing only 17-61 predicted peptides for each QTL, although CIs covered large genetic distances. Knowledge of correlated behavioral traits, comparative bioinformatics, and expression assays facilitated evaluation of candidate genes. An overrepresentation of genes involved in ovarian development and insulin-like signaling components within pollen foraging QTL regions suggests that an ancestral reproductive gene network was co-opted during the evolution of foraging specialization. The major QTL influencing defensive/aggressive behavior contains orthologs of genes involved in central nervous system activity and neurogenesis. Candidates at the other two defensive-behavior QTLs include modulators of sensory signaling (Am5HT(7) serotonin receptor, AmArr4 arrestin, and GABA-B-R1 receptor). These studies are the first step in linking natural variation in honeybee social behavior to the identification of underlying genes.

The genetic architecture of sucrose responsiveness in the honeybee (Apis mellifera L.).

One of the best examples of a natural behavioral syndrome is the pollen-hoarding syndrome in honeybees that ties together multiple behavioral phenotypes, ranging from foraging behavior to behavioral ontogeny and learning performance. A central behavioral factor is the bees' responsiveness to sucrose, measured as their proboscis extension reflex. This study examines the genetics of this trait in diploid worker and haploid male honeybees (drones) to learn more about the genetic architecture of the overall behavioral syndrome, using original strains selected for pollen-hoarding behavior. We show that a significant proportion of the phenotypic variability is determined by genotype in males and workers. Second, our data present overwhelming evidence for pleiotropic effects of previously identified quantitative trait loci for foraging behavior (pln-QTL) and epistatic interactions among them. Furthermore, we report on three genomic QTL scans (two reciprocal worker backcrosses and one drone hybrid population) derived from our selection strains. We present at least one significant and two putative new QTL directly affecting the sucrose response of honeybees. Thus, this study demonstrates the modular genetic architecture of behavioral syndromes in general, and elucidates the genetic architecture of the pollen-hoarding behavioral syndrome in particular. Understanding this behavioral syndrome is important for understanding the division of labor in social insects and social evolution itself.

Chemosensory processing in the fruit fly, Drosophila melanogaster: generalization of a feeding response reveals overlapping odour representations.

Insects are capable of detecting, and discriminating between, a very large number of odours. The biological relevance of many of those odours, particularly those related to food, must first be learned. Given that the number of sensory receptors and antennal lobe (AL) glomeruli is limited relative to the number of odours that must be detectable, this ability implies that the olfactory system makes use of a combinatorial coding scheme whereby each sensory cell or AL projection neuron can participate in coding for several different odours. An important step in understanding this coding scheme is to behaviourally quantify the degree to which sets of odours are discriminable. Here we evaluate odour discriminability in the fruit fly, Drosophila melanogaster, by first conditioning individual flies to not respond to any of several odorants using a nonassociative conditioning protocol (habituation). We show that flies habituate unconditioned leg movement responses to both mechanosensory and olfactory stimulation over 25 unreinforced trials. Habituation is retained for at least 2 h and is subject to dishabituation. Finally, we test the degree to which the conditioned response generalizes to other odorants based on molecular features of the odorants (e.g. carbon chain length and the presence of a target functional group). These tests reveal predictable generalization gradients across these molecular features. These data substantiate the claim that these features are relevant coding dimensions in the fruit fly olfactory system, as has been shown for other insect and vertebrate species.