Effect of bacterial toxins on the mitogen-induced increase of the Ca2+ concentration in the cytoplasm of rat thymocytes. The role of N proteins

The effect of bacterial toxins, modifying the activity of regulatory N proteins of adenylate cyclase and probably other systems, on the mitogen-induced changes of cytosolic free Ca2+ concentration ([Ca2+]i) has been studied using Ca2+ fluorescent probe quin-2. It is shown that treatment of thymocytes with cholera toxin, E. coli heat-labile (HL) toxin or pertussis toxin abolishes the concanavalin A (con A)-induced rise of [Ca2+]i. The inhibitory effect of cholera and HL toxins can be explained by the toxin-induced rise of intracellular cAMP. The effect of pertussis toxin indicates the involvement of N proteins in the action of con A receptor and in generation of Ca2+-signal during the mitogenic activation of thymocytes.     

The Pore-Forming Properties of SsoHel308 Helicase from Saccharolobus solfataricus

The pore-forming activity of SsoHel308 helicase from extreme thermophilic archaea Saccharolobus solfataricus has been demonstrated for the first time. This protein embedded in rabbit erythrocyte membranes may cause erythrocyte hemolysis. It has been shown that this enzyme forms pores in a planar artificial bilayer membrane and acts as a transformer. After embedding this enzyme into biolayer lipid membranes, the membrane conductivity is altered. Taken together, our results show that SsoHel308 helicase is able to form pores in artificial bilayer membranes and, in some cases, the current that flows across the membranes shares features typical of ion channels. The short lifetime of the pores in the membrane significantly reduces the toxicity of helicase for a living cell. The possibility of directed translocation of single-stranded DNA in the presence of ATP will enable the use of this enzyme as a molecular syringe for injecting single-stranded DNA into living cells.

     

A search for Y-chromosomal species-specific markers and their use for hybridization analysis in ground squirrels (Spermophilus: Rodentia, sciuridae)

In four ground squirrel species from the Volga region—yellow (Spermophilus fulvus), russet (S. major), little (S. pygmaeus), and speckled (S. suslicus)—four hybridization variants (major/fulvus, major/pygmaeus, major/suslicus, and pygmaeus/suslicus) have been reliably described. Earlier we have shown that populations of S. major from the Volga region were characterized by wide introgression of mtDNA from S. fulvus and S. pygmaeus, which probably, resulted from ancient hybridization [5]. In this study, the same populations were used to analyze the introgression of the Y chromosome, which (unlike mtDNA) is paternally inherited. Three genes, ZfY, SRY, and SmcY were tested as Y-chromosomal candidate markers. It was demonstrated that Y chromosome of ground squirrels lacked the ZfY gene, while its homologous structure, ZfY(X), was presumably linked to the X chromosome. The SRY region examined was rather conservative. In particular, the sequences determined in S. major and S. fulvus were identical, while three out of four substitutions found in S. pygmaeus were located in the coding region. The SmcY gene was found to be the most suitable marker, providing distinguishing of all of the four ground squirrel species by nine nucleotide substitutions. Introgression at the Y chromosome was observed only in two cases: in one S. major individual (out of 51 phenotypically pure animals) caught in the major/fulvus sympatry zone, and in four (one litter) out of fourteen S. fulvus individuals caught in close vicinity of the sympatry zone of these two species. Among 28 S. pymaeus and 9 S. suslicus individuals, no foreign SmcY genes were detected. Two colonies of the “hybrid swarm” type were examined with eight major/suslicus hybrids analyzed in the first and seventeen major/fulvus hybrids in the second colony. The prevalence of the S. major paternal lineages was observed in both colonies (87.5 and 82.4%, respectively). The data obtained suggest that compared to wide mtDNA introgression, introgression of Y chromosome in the Volga region ground squirrels is statistically significantly less frequent event.     

Burden of Giardia duodenalis Infection and Its Adverse Effects on Growth of Schoolchildren in Rural Malaysia

Background

Giardia duodenalis infection and malnutrition are still considered as public health problems in many developing countries especially among children in rural communities. This study was carried out among Aboriginal (Orang Asli) primary schoolchildren in rural peninsular Malaysia to investigate the burden and the effects of Giardia infection on growth (weight and height) of the children.

Methods/Findings

Weight and height of 374 children aged 7–12 years were assessed before and after treatment of Giardia infection. The children were screened for Giardia parasite using trichrome staining technique. Demographic and socioeconomic data were collected via face-to-face interviews using a pre-tested questionnaire. Overall, 22.2% (83/374) of the children were found to be infected with Giardia. Nutritional status of children was assessed and the results showed that the mean weight and height were 23.9 kg (95% CI = 23.3, 24.5) and 126.6 cm (95% CI = 125.6, 127.5), respectively. Overall, the prevalence of severe underweight, stunting and wasting were 28.3%, 23.8% and 21.0%, respectively. Multiple linear regression analyses showed sex, Giardia infection and household monthly income as the significant determinants of weight while sex and level of mother''s education were the significant determinants of height. Weight and height were assessed at 3 and 6 months after treatment of Giardia infection. It was found that Giardia infection has a significant association with the weight of children but not with height.

Conclusions/Significance

This study reveals high prevalence of Giardia infection and malnutrition among Aboriginal children in rural Malaysia and clearly highlights an urgent need to identify integrated measures to control these health problems in the rural communities. Essentially, proper attention should be given to the control of Giardia infection in Aboriginal communities as this constitutes one of the strategies to improve the nutritional status of Aboriginal children.     

Intensive protein synthesis in neurons and phosphorylation of beta-amyloid precursor protein and tau-protein are triggering factors of neuronal amyloidosis and Alzheimer’s disease

Studies of Alzheimer’s disease have become particularly important and attract now much attention of scientists all over the world due to worldwide dissemination of this dangerous disorder. Causes of this pathology still remain unknown, while the final image, originally obtained on microscopic brain sections from patients with this disease more than a hundred years ago, is well familiar to clinicians. This includes deposition of amyloid-β (Aβ) in the brain tissue of senile plaques and fibrils. Many authors believe that the deposition of Aβ provokes secondary neuronal changes, responsible for death of neurons. Other authors associate the death of neurons with hyperphosphorylation of tau-proteins, which form neurofibrillar tangles inside nerve cells and cause their death. Creation of methods of preclinical diagnostics and effective treatment of Alzheimer’s disease requires novel knowledge: on the nature of triggering factors of sporadic forms of Alzheimer’s disease, on cause-effect relationships of phosphorylation of amyloid precursor protein with formation of pathogenic beta-amyloids, on the relationship between these factors underlying tau-protein hyperphosphorylation and neuron death. In this review we have analyzed reports describing increased intensity of protein synthesis in neurons under normal and various stress conditions, possibility of development of energy imbalance of neurons and activation of their protective systems. Phosphorylation and hyperphosphorylation of tau-proteins is also tightly associated with protective mechanisms of cells and with processes of evacuation of phosphates, adenosine monophosphates and pyrophosphates from the region of protein synthesis. Prolonged highly intensive protein synthesis causes overload of protective mechanisms and impairments in concerted metabolic processes. This leads to neuronal dysfunction, transport collapse, and death of neurons.     

Glycolipids of Pseudomonas and Rhodococcus oil-degrading bacteria used in bioremediation preparations: Formation and structure

We studied formation and structural features of biosurfactants produced by five oil-degrading Pseudomonas and Rhodococcus strains. These bacteria were found to be capable of intense formation of extracellular glycolipid biosurfactants when grown on mineral salts medium with 2% hexadecane. Under these conditions, the surface tension of the cultures decreased from 77 mN/m to 31–34 mN/m. The strain Rhodococcus sp. S26 forming up to 780 mg glycolipids/l of culture medium proved the most efficient biosurfactant producer. Extracellular glycolipids were purified from the crude extracts by column chromatography. Their structural features were determined by thin layer chromatography and electrospray ionization mass spectrometry. Strains Pseudomonas putida BS3701 and Pseudomonas fluorescens 142NF synthesized a number of glycolipids identified as rhamnolipid B and its homologues. Glycolipids produced by Rhodococcus sp. X5 and Rhodococcus sp. S26 were assigned to trehalose tetraesters.     

Subtype Distribution of Blastocystis Isolates in Sebha,Libya

Background

Blastocystis is a genetically diverse and a common intestinal parasite of humans with a controversial pathogenic potential. This study was carried out to identify the Blastocystis subtypes and their association with demographic and socioeconomic factors among outpatients living in Sebha city, Libya.

Methods/Findings

Blastocystis in stool samples were cultured followed by isolation, PCR amplification of a partial SSU rDNA gene, cloning, and sequencing. The DNA sequences of isolated clones showed 98.3% to 100% identity with the reference Blastocystis isolates from the Genbank. Multiple sequence alignment showed polymorphism from one to seven base substitution and/or insertion/deletion in several groups of non-identical nucleotides clones. Phylogenetic analysis revealed three assemblage subtypes (ST) with ST1 as the most prevalent (51.1%) followed by ST2 (24.4%), ST3 (17.8%) and mixed infections of two concurrent subtypes (6.7%).

Blastocystis

ST1 infection was significantly associated with female (P = 0.009) and low educational level (P = 0.034). ST2 was also significantly associated with low educational level (P= 0.008) and ST3 with diarrhoea (P = 0.008).

Conclusion

Phylogenetic analysis of Libyan Blastocystis isolates identified three different subtypes; with ST1 being the predominant subtype and its infection was significantly associated with female gender and low educational level. More extensive studies are needed in order to relate each Blastocystis subtype with clinical symptoms and potential transmission sources in this community.     

Rhizobium leguminosarum genes required for expression and transfer of host specific nodulation

The contributions of various nod genes from Rhizobium leguminosarum biovar viceae to host-specific nodulation have been assessed by transferring specific genes and groups of genes to R. leguminosarum bv. trifolii and testing the levels of nodulation on Pisum sativum (peas) and Vicia hirsuta. Many of the nod genes are important in determination of host-specificity; the nodE gene plays a key (but not essential) role and the efficiency of transfer of host specific nodulation increased with additional genes such that nodFE < nodFEL < nodFELMN. In addition the nodD gene was shown to play an important role in host-specific nodulation of peas and Vicia whilst other genes in the nodABCIJ gene region also appeared to be important. In a reciprocal series of experiments involving nod genes cloned from R. leguminosarum bv. trifolii it was found that the nodD gene enabled bv. viciae to nodulate Trifolium pratense (red clover) but the nodFEL gene region did not. The bv. trifolii nodD or nodFEL genes did significantly increase nodulation of Trifolium subterraneum (sub-clover) by R. leguminosarum bv. viciae. It is concluded that host specificity determinants are encoded by several different nod genes.     

Subcloning of DNA fragments of the simian adenovirus SA7 oncogene in bacteriophage M13

The XmaI/PstI and XmaI DNA fragments of adenovirus SA7 oncogene and the adjacent region (16.7% of the physical map of SA7 left end DNA) were recloned in M13 bacteriophages mp8 and mp9 in order to obtain the singlestranded fragments EIa and EIb from the DNA region of monkey adenovirus SA7 located on the recombinant plasmid pASP carrying the DNA APstI fragment including the adenovirus SA7 oncogene.