Male- and female-specific variants of doublesex gene products have different roles to play towards regulation of Sex combs reduced expression and sex comb morphogenesis in Drosophila

Sexually dimorphic characters have two-fold complexities in pattern formation as they have to get input from both somatic sex determination as well as the positional determining regulators. Sex comb development in Drosophila requires functions of the somatic sex-determining gene doublesex and the homeotic gene Sex combs reduced. Attempts have not been made to decipher the role of dsx in imparting sexually dimorphic expression of SCR and the differential function of sex-specific variants of dsx products in sex comb development. Our results in this study indicate that male-like pattern of SCR expression is independent of dsx function, and dsx ^F must be responsible for bringing about dimorphism in SCR expression, whereas dsx ^M function is required with Scr for the morphogenesis of sex comb.     

Acute outcome of treating patients admitted with electrical storm in a tertiary care centre

Background

Electrical storm (ES) is a life threatening emergency. There is little data available regarding acute outcome of ES.

Aims

The study aimed to analyze the acute outcome of ES, various treatment modalities used, and the factors associated with mortality.

Methods

This is a retrospective observational study involving patients admitted with ES at our centre between 1/1/2007 and 31/12/2013.

Results

41 patients (mean age 54.61 ± 12.41 years; 86.7% males; mean ejection fraction (EF) 44.51 ± 16.48%) underwent treatment for ES. Hypokalemia (14.63%) and acute coronary syndrome (ACS) (14.63%) were the commonest identifiable triggers. Only 9 (21.95%) patients already had an ICD implanted. Apart from antiarrhythmic drugs (100%), deep sedation (87.8%), mechanical ventilation (24.39%) and neuraxial modulation using left sympathetic cardiac denervation (21.95%) were the common treatment modalities used. Thirty-three (80.49%) patients could be discharged after a mean duration of 14.2 ± 2.31 days. Eight (19.5%) patients died in hospital. The mortality was significantly higher in those with EF < 35% compared to those with a higher EF (8 (42.11% vs 0 (0%), p = 0.03)). There was no significant difference in mortality between those with versus without a structural heart disease (8 (21.1% vs 0 (0%), p = 0.32)). Comparison of mortality an ACS with ES versus ES of other aetiologies (3 (50%) vs 5 (14.29) %, p = 0.076)) showed a trend towards significance.

Conclusion

With comprehensive treatment, there is reasonable acute survival rate of ES. Hypokalemia and ACS are the commonest triggers of ES. Patients with low EF and ACS have higher mortality.     

Occurrence of islands in genomes of <Emphasis Type="Italic">Sinorhizobium meliloti</Emphasis> native isolates

Genomes of 184 Sinorhizobium meliloti native isolates were studied to test the occurence of islands Sme21T, Sme19T, and Sme80S previously described in the model strain Rm1021. This analysis was conducted using PCR methodology involving specific primers. It was demonstrated that, in the examined geographically distinct populations of S. meliloti from the Northern Caucasus (NCG) and the Aral Sea region (PAG), the strains containing genomic islands were observed with similar frequency (0.55 and 0.57, respectively). Island Sme80S, denoted as an island of “environmental adaptivity,” was identified predominantly (frequency of 0.38) in genomes of strains which exhibited a lower level of salt tolerance and was isolated in PAG, a modern center of introgressive hybridization of alfalfa subjected to salinity. Island Sme21T designated as “ancestral” was observed in genomes of strains isolated in NCG, the primary center of host-plant biodiversity, 10-fold more often than in strains from PAG. An island Sme19T, which predominantly carries genes encoding transposases, was observed in genomes of strains in both populations with average frequency of 0.10. The analysis of linkage disequilibrium (LD) based on the assessment of probability for detection of different islands combinations in genomes revealed an independent inheritance of islands in salt-sensitive strains of various geographic origin. In contrast, the absence of this trend was noted in the majority of the examined combinations of salt-tolerant strains. It was concluded that the structure of chromosome in PAG strains which predominantly possessed a salt-sensitive phenotype was subjected to active recombinant processes, which could predetermine the intensity of microevolutionary processes in bacterial populations and facilitate an adaptation of bacteria in adverse environmental effect.     

Super-suppressor induced interallelic complementation

Summary In yeast the dominant super-suppressorS ₅ has a distinct expression in heterozygotes depending on the particular combination of alleles at thead ₁ orad ₂ loci. If thead ₁ combination is represented by two suppressible alleles, the phenotype of diploid is wild. If thead ₁ combination consists of a suppressible and a non-suppressible allele the phenotype of the diploid is partially mutant. Such a difference in the manifestation of suppressor depending on the combination of alleles is more pronounced in the case ofad ₂ mutations. In the case when bothad ₂ alleles are suppressible, the diploid is prototrophic, but when only one allele is suppressible, the diploid is an adenineless auxotroph as a rule.This type ofS ₅-effect gave us the possibility to study interallelic complementation atad ₂ locus in presence of the super-suppressor. It was shown that some combinations of noncomplementing alleles do complement as a result of suppression.Comparison of the two complementation maps with and without suppressor is made for thead ₂ locus. The mechanisms of the phenomena and of super-suppression are discussed.     

Influence of salt stress on the genetically polymorphic system of Sinorhizobium meliloti-Medicago truncatula

The impacts of salt stress (75 mM NaCl) on the ecological efficiency of the genetically polymorphic Sinorhizobium meliloti-Medicago truncatula system were studied. Its impact on a symbiotic system results in an increase of the partners’ variability for symbiotic traits and of the symbiosis integrity as indicated by: (a) the specificity of the partners’ interactions-the nonadditive inputs of their genotypes into the variation of symbiotic parameters and (b) the correlative links between these parameters. The structure of the nodD1 locus and the plasmid content correlates to the efficiency of the symbiosis between S. meliloti and M. truncatula genotypes under stress conditions more sufficiently than in the absence of stress. Correlations between the symbiotic efficiency of rhizobia strains and their growth rate outside symbiosis are expressed under stress conditions, not in the absence of stress. Under salt stress symbiotic effectiveness was decreased for M. truncatula line F83005.5, which was salt sensitive for mineral nutrition. The inhibition of symbiotic activity for this line is linked with decreased nodule formation, whereas for Jemalong 6 and DZA315.16 lines it is associated with repressed N₂-fixation. It was demonstrated for the first time that salt stress impairs the M. truncatula habitus (the mass: height ratio increased 2- to 6-fold), which in the salt-resistant cultivar Jemalong 6 is normalized as the result of rhizobia inoculation.     

Structural Polymorphism of <Emphasis Type="Italic">Sinorhizobium meliloti</Emphasis> Genes Related to Virulence and Salt Tolerance

Analysis of the structural polymorphism of eight genes in Sinorhizobium meliloti (nodA, nodB, nodC, and nodH, as well as betA, betB, betC, and betB2) involved in virulence control and salt tolerance, respectively, was carried out in native populations from two geographically distant areas of alfalfa diversity. These areas are located in the North Caucasian gene center of cultivated plants (NCG) and in the modern center of introgressive hybridization of alfalfa located next to the Aral Sea area (PAG) subjected to salinization. RFLP types (alleles) of the nod and bet genes, similar to those in the reference strain Rm1021 (A-type) and different from them (divergent, or D-type alleles) were revealed. The combinations for A- and D-type alleles of the aforementioned genes (analysis of the linkage disequilibrium, LD) were studied in both populations. It was shown that D-type alleles of the nod genes were two times more frequent in the NCG population, while D-type alleles of the bet genes were predominantly identified in the PAG population. At the same time, different combinations of D-type alleles of both the nod and bet genes prevailed in populations. For instance, in the case of the glycine betaine metabolism pathway, these were the betC and betB2 genes in NCG population and betB and betA genes in PAG population. The state of linkage disequilibrium was shown for 60.7% of combinations of alleles of the nod and bet genes in the S. meliloti strains from NCG and more than twice less in strains from the PAG population. It was concluded that clonal lines prevailed in NCG, while the PAG population of S. meliloti had a panmictic structure with revealed single clonal lines.     

Analysis of various types of competition in Tn5-mutants of alfalfa rhizobium bacteria (Sinorhizobium meliloti)]

Nodulation, rhizospheral, and saprophytic types of competitiveness (NC, RC, and SC, respectively) were studied in the highly active strains CXM1-105 and CXM1-188 of the alfalfa rhizobium Sinorhizobium meliloti. The competitiveness was estimated with the use of markers of antibiotic resistance. It was found that the mutant strain T37, which was characterized by a drastically decreased NC, had higher SC and RC than the parental strain. The mutant T107 (with a moderately decreased NC) did not differ from the parental strain with respect to RC but had a higher SC. The mutant T27 (with the lowest NC) did not differ from the parental strain with respect to SC or RC. In the mutant Tb1, the NC and RC were decreased and the SC was the same as in the parental strain. In Tb7, the SC was decreased and RC was increased. In the mutant T795, all of the three types of competitiveness were decreased. The difference between the mutants studied and the parental strain with respect to NC and RC was confirmed using an indirect method (the ability to form effective symbiosis after mixed inoculation together with the an ineffective tester strain CXM1-48) and the X-Gluc staining method (using the S. meliloti RmM4gus tester strain carrying the gene of beta-glucuronidase). However, the decreased SC that the mutants exhibited when they were cultivated together with parental strains in a plant-growth substrate (vermiculite) was not observed in the case of their cocultivation in liquid media. The independent variation of different types of competitiveness indicate that rhizobia have several separate gene systems determining their survival in in planta and ex planta ecological niches.     

Comparison of the adaptive potential for Rhizobium leguminosarum bv. viceae nodule bacterial populations isolated in natural ecosystems and agrocenoses

Polymorphism analysis was performed in Rhizobium leguminosarum bv. viceae populations isolated from geographically distant regions of Ukraine and Middle Asia. Examination of cultural, biochemical, and symbiotic traits revealed interpopulation differences, which were attributed to the difference in conditions between natural ecosystems and agrocenoses. Vetch has high species diversity and is not cultivated in Middle Asia, and the corresponding rhizobial population displayed higher genetic diversity and higher polymorphism of adaptive traits ensuring saprophytic development in soil and the rhizosphere, including melanin synthesis (35%) and active exopolysaccharide production (90%). Strains of the Ukrainian population had a lower exopolysaccharide production (10%), did not produce melanin, had higher herbicide resistance, and utilized glucose and succinate (main components of plant root exudation) as carbon sources. Strains capable of efficient symbiosis with Vicia villosa Roth. had a higher frequency in the Middle Asian than in the Ukrainian population, especially among strains isolated from soil (80 and 35%, respectively). In addition, strains of the Middle Asian population better competed for nodulation. It was assumed that the formation of rhizobial populations in vetch cultivation regions (Ukraine) is aimed at adaptation to ectosymbiotic (rhizospheric) interactions with plants and anthropogenic stress factors, while strains of the vetch original center (Middle Asia) are mostly adapted to the endosymbiotic interaction and to natural edaphic stress factors.     

Galega orientalis is more diverse than Galega officinalis in Caucasus--whole-genome AFLP analysis and phylogenetics of symbiosis-related genes

Legume plants can obtain combined nitrogen for their growth in an efficient way through symbiosis with specific bacteria. The symbiosis between Rhizobium galegae and its host plant Galega is an interesting case where the plant species G. orientalis and G. officinalis form effective, nitrogen‐fixing, symbioses only with the appropriate rhizobial counterpart, R. galegae bv. orientalis and R. galegae bv. officinalis, respectively. The symbiotic properties of nitrogen‐fixing rhizobia are well studied, but more information is needed on the properties of the host plants. The Caucasus region in Eurasia has been identified as the gene centre (centre of origin) of G. orientalis, although both G. orientalis and G. officinalis can be found in this region. In this study, the diversity of these two Galega species in Caucasus was investigated to test the hypothesis that in this region G. orientalis is more diverse than G. officinalis. The amplified fragment length polymorphism fingerprinting performed here showed that the populations of G. orientalis and R. galegae bv. orientalis are more diverse than those of G. officinalis and R. galegae bv. officinalis, respectively. These results support the centre of origin status of Caucasus for G. orientalis at a genetic level. Analysis of the symbiosis‐related plant genes NORK and Nfr5 reveals remarkable diversity within the Nfr5 sequence, although no evidence of adaptive evolution could be found.