Showing papers in "Journal of Genetics in 2010"

Doublesex: a conserved downstream gene controlled by diverse upstream regulators.

Abstract: Sex determination, an integral precursor to sexual reproduction, is required to generate morphologically distinct sexes. The molecular components of sex-determination pathways regulating sexual differentiation have been identified and characterized in different organisms. The Drosophila doublesex (dsx) gene at the bottom of the sex-determination cascade is the best characterized candidate so far, and is conserved from worms (mab3 of Caenorhabditis elegans) to mammals (Dmrt-1). Studies of dsx homologues from insect species belonging to different orders position them at the bottom of their sex-determination cascade. The dsx homologues are regulated by a series of upstream regulators that show amazing diversity in different insect species. These results support the Wilkin’s hypothesis that evolution of the sex-determination cascade has taken place in reverse order, the bottom most gene being most conserved and the upstream genes having been recruited at different times during evolution. The pre-mRNA of dsx is sex-specifically spliced to encode male or female-specific transcription factors that play an important role in the regulation of sexually dimorphic characters in different insect species. The generalization that dsx is required for somatic sexual differentiation culminated with its functional analysis through transgenesis and knockdown experiments in diverse species of insects. This brief review will focus on the similarities and variations of dsx homologues that have been investigated in insects to date.

Comparative evaluation of genetic diversity using RAPD, SSR and cytochrome P450 gene based markers with respect to calcium content in finger millet (Eleusine coracana L. Gaertn.).

Abstract: Genetic relationships among 52 Eleusine coracana (finger millet) genotypes collected from different districts of Uttarakhand were investigated by using randomly amplified polymorphic DNA (RAPD), simple sequence repeat (SSR) and cytochrome P450 gene based markers. A total of 18 RAPD primers, 10 SSR primers, and 10 pairs of cytochrome P450 gene based markers, respectively, revealed 49.4%, 50.2% and 58.7% polymorphism in 52 genotypes of E. coracana. Mean polymorphic information content (PIC) for each of these marker systems (0.351 for RAPD, 0.505 for SSR and 0.406 for cyt P450 gene based markers) suggested that all the marker systems were effective in determining polymorphisms. Pair-wise similarity index values ranged from 0.011 to 0.999 (RAPD), 0.010 to 0.999 (SSR) and 0.001 to 0.998 (cyt P450 gene based markers) and mean similarity index value of 0.505, 0.504 and 0.499, respectively. The dendrogram developed by RAPD, SSR and cytochrome P450 gene based primers analyses revealed that the genotypes are grouped in different clusters according to high calcium (300‐450 mg/100 g), medium calcium (200‐300 mg/100 g) and low calcium (100‐200 mg/100 g). Mantel test employed for detection of goodness of fit established cophenetic correlation values above 0.95 for all the three marker systems. The dendrograms and principal coordinate analysis (PCA) plots derived from the binary data matrices of the three marker systems are highly concordant. High bootstrap values were obtained at major nodes of phenograms through WINBOOT software. Comparison of RAPD, SSR and cytochrome P450 gene based markers, in terms of the quality of data output, indicated that SSRs and cyt P450 gene based markers are particularly promising for the analysis of plant genome diversity. The genotypes of finger millet collected from different districts of Uttarakhand constitute a wide genetic base and clustered according to calcium contents. The identified genotypes could be used in breeding programmes and a major input into conservation biology of cereal crops.

SSR mining in oil palm EST database: application in oil palm germplasm diversity studies

Abstract: This study reports on the detection of additional expressed sequence tags (EST) derived simple sequence repeat (SSR) markers for the oil palm. A large collection of 19243 Elaeis guineensis ESTs were assembled to give 10258 unique sequences, of which 629 ESTs were found to contain 722 SSRs with a variety of motifs. Dinucleotide repeats formed the largest group (45.6%) consisting of 66.9% AG/CT, 21.9% AT/AT, 10.9% AC/GT and 0.3% CG/CG motifs. This was followed by trinucleotide repeats, which is the second most abundant repeat types (34.5%) consisting of AAG/CTT (23.3%), AGG/CCT (13.7%), CCG/CGG (11.2%), AAT/ATT (10.8%), AGC/GCT (10.0%), ACT/AGT (8.8%), ACG/CGT (7.6%), ACC/GGT (7.2%), AAC/GTT (3.6%) and AGT/ACT (3.6%) motifs. Primer pairs were designed for 405 unique EST-SSRs and 15 of these were used to genotype 105 E. guineensis and 30 E. oleifera accessions. Fourteen SSRs were polymorphic in at least one germplasm revealing a total of 101 alleles. The high percentage (78.0%) of alleles found to be specific for either E. guineensis or E. oleifera has increased the power for discriminating the two species. The estimates of genetic differentiation detected by EST-SSRs were compared to those reported previously. The transferability across palm taxa to two Cocos nucifera and six exotic palms is also presented. The polymerase chain reaction (PCR) products of three primer-pairs detected in E. guineensis, E. oleifera, C. nucifera and Jessinia bataua were cloned and sequenced. Sequence alignments showed mutations within the SSR site and the flanking regions. Phenetic analysis based on the sequence data revealed that C. nucifera is closer to oil palm compared to J. bataua; consistent with the taxanomic classification.

Application of RNA interference in treating human diseases.

Abstract: Gene silencing can occur either through repression of transcription, termed transcriptional gene silencing (TGS), or through translation repression andmRNA degradation, termed posttranscriptional gene silencing (PTGS). PTGS results from sequence-specific mRNA degradation in the cytoplasm without dramatic changes in transcription of corresponding gene in nucleus. Both TGS and PTGS are used to regulate endogenous genes. Interestingly, mechanisms for gene silencing also protect the genome from transposons and viruses. In this paper, we first review RNAi mechanism and then focus on some of its applications in biomedical research such as treatment for HIV, viral hepatitis, cardiovascular and cerebrovascular diseases, metabolic disease, neurodegenerative disorders and cancer.

Molecular assessment of genetic diversity in cluster bean (Cyamopsis tetragonoloba) genotypes.

Abstract: . 1999;Henry and Mathur 2005) but such traits are influenced byenvironmental factors and developmental stage of the plant.Molecular markers offer several advantages over the conven-tional breeding tools for selection of diverse parents. Ran-domly amplified polymorphic DNA (RAPD) uses arbitrary10-baseprimersto amplifythe randomportionofthegenome(Williams

Genetics of sex determination in the haplodiploid wasp Nasonia vitripennis (Hymenoptera: Chalcidoidea)

Abstract: The parasitoid wasp Nasonia vitripennis reproduces by haplodiploidy; males are haploid and females are diploid. Sex determination in Nasonia is not governed by complementary alleles at one or more sex loci. As in most other insects, the sex-determining pathway consists of the basal switch doublesex that is sex-specifically regulated by transformer. Analysis of a polyploid and a mutant gynandromorphic strain, suggested a parent-specific effect (imprinting) on sex determination in Nasonia. Zygotic activity of transformer is autoregulated and depends on a combination of maternal provision of tra mRNA and a paternal genome set. This constitutes a novel way of transformer control in insect sex determination implying maternal imprinting. The nature of the maternal imprint is not yet known and it remains to be determined how broadly the Nasonia sex-determining mechanism applies to other haplodiploids.

Comparing genetic ancestry and self-reported race/ethnicity in a multiethnic population in New York City.

Abstract: Self-reported race/ethnicity is frequently used in epidemiological studies to assess an individual’s background origin. However, in admixed populations such as Hispanic, self-reported race/ethnicity may not accurately represent them genetically because they are admixed with European, African and Native American ancestry. We estimated the proportions of genetic admixture in an ethnically diverse population of 396 mothers and 188 of their children with 35 ancestry informative markers (AIMs) using the STRUCTURE version 2.2 program. The majority of the markers showed significant deviation from Hardy–Weinberg equilibrium in our study population. In mothers self-identified as Black and White, the imputed ancestry proportions were 77.6% African and 75.1% European respectively, while the racial composition among self-identified Hispanics was 29.2% European, 26.0% African, and 44.8% Native American. We also investigated the utility of AIMs by showing the improved fitness of models in paraoxanase-1 genotype–phenotype associations after incorporating AIMs; however, the improvement was moderate at best. In summary, a minimal set of 35 AIMs is sufficient to detect population stratification and estimate the proportion of individual genetic admixture; however, the utility of these markers remains questionable.

Mapping of QTL for tiller number at different stages of growth in wheat using double haploid and immortalized F2 populations.

Abstract: Effective tiller number is one of the most important traits for wheat (Triticum aestivum L.) yield, but the inheritance of tillering is poorly understood. A set of 168 doubled haploid (DH) lines derivatives of a cross between two winter wheat cultivars (Huapei 3 and Yumai 57), and an immortalized F2 (IF2) population generated by randomly permutated intermating of these DHs were investigated, and QTLs of tillering related to the maximum tillering of pre-winter (MTW), maximum tillering in spring (MTS), and effective tillering in harvest (ETH) were mapped. Phenotypic data were collected for the two populations from two different environments. Using inclusive composite interval mapping (ICIM), a total of 9 and 18 significant QTL were detected across environments for tillering in the DH and IF2 populations, respectively. Four QTLs were common between two populations. A major QTL located on the 5D chromosome with the allele originating from Yumai 57 was detected and increased 1.92 and 3.55 tillers in MTW and MTS, respectively. QTLs (QMts6D, QEth6D) having a neighbouring marker interval at Xswes679.1 and Xcfa2129 on chromosome 6D was detected in MTS and ETH. These results provide a better understanding of the genetic factors for selectively expressing the control of tiller number in different growth stages and facilitate marker-assisted selection strategy in breeding.

Meiotic behaviour of tetraploid wheats (Triticum turgidum L.) and their synthetic hexaploid wheat derivates influenced by meiotic restitution and heat stress

Abstract: Meiotic restitution is considered to be a common mechanism of polyploidization in plants and hence is one of the most important processes in plant speciation. Meiotic behaviour of plant chromosomes is influenced by both genetic and environmental factors. In this study, the meiotic behaviour of cereal crops was investigated, which includes tetraploid wheat genotypes (with and without the meiotic restitution trait) and their derivates (synthetic hexaploid wheats and a doubled haploid (DH) line), grown at two planting dates in the field. In addition, two local landraces of emmer wheat (Triticum turgidum ssp. dicoccum), one wheat cultivar (Chinese spring), one DH triticale cultivar (Eleanor) and one rye accession were included. Immature spikes of mid-autumn and end-winter sowing plants were collected in April and May 2008, respectively, fixed in Carnoy's solution and stained with hematoxylin. Pollen mother cells (PMCs) from anthers at different stages of meiotic process were analysed for their chromosomal behaviour and irregularities. Meiotic aberrations such as laggards, chromosome bridges, micronuclei, abnormal cytokines, chromatin pulling and meiotic restitution were observed and the studied genotypes were accordingly ranked as follows: triticale > synthetic hexaploid wheats > tetraploid wheats possessing meiotic restitution > tetraploid wheats lacking meiotic restitution > rye. The results indicated that the samples that had been planted in the autumn, thus experiencing an optimum temperature level at the flowering stage, exhibited less meiotic irregularities than winter planting samples that encountered heat stress at the flowering period.

Host genetic factors in susceptibility to HIV-1 infection and progression to AIDS

Abstract: HIV-1 infection has rapidly spread worldwide and has become the leading cause of mortality in infectious diseases. The duration for development of AIDS (AIDS progression) is highly variable among HIV-1 infected individuals, ranging from 2-3 years to no signs of AIDS development in the entire lifetime. Several factors regulate the rate at which HIV-1 infection progresses to AIDS. Host genetic factors play an important role in the outcome of such complex or multifactor diseases as AIDS and are also known to regulate the rate of disease progression. This review focuses on the major host genes reported to affect the progression to AIDS in HIV-1 infected individuals.

fruitless alternative splicing and sex behaviour in insects: an ancient and unforgettable love story?

Abstract: Courtship behaviours are common features of animal species that reproduce sexually. Typically, males are involved in courting females. Insects display an astonishing variety of courtship strategies primarily based on innate stereotyped responses to various external stimuli. In Drosophila melanogaster, male courtship requires proteins encoded by the fruitless (fru) gene that are produced in different sex-specific isoforms via alternative splicing. Drosophila mutant flies with loss-of-function alleles of the fru gene exhibit blocked male courtship behaviour. However, various individual steps in the courtship ritual are disrupted in fly strains carrying different fru alleles. These findings suggest that fru is required for specific steps in courtship. In distantly related insect species, various fru paralogues were isolated, which shows conservation of sex-specific alternative splicing and protein expression in neural tissues and suggests an evolutionary functional conservation of fru in the control of male-specific-courtship behaviour. In this review, we report the seminal findings regarding the fru gene, its splicing regulation and evolution in insects.

Sex determination: insights from the silkworm.

Abstract: The sex-determining system differs considerably among organisms. Even among insect species, the genetic system for sexdetermination is highly diversified. In Drosophila melanogaster, somatic sexual differentiation is regulated by a well characterized genetic hierarchy X:A > Sxl > tra/tra2 > dsx and fru. This cascade seems to control sex determination in all Drosophila species and is partially conserved in another dipteran species, Ceratitis capitata: Cctra/Cctra-2 > Ccdsx and Ccfru. However, in the silkworm, Bombyx mori, femaleness is determined by the presence of a dominant feminizing factor on the W chromosome. Moreover, no sex-specific regulatory Sxl homolog has been isolated from B. mori. Also, no tra homolog has yet been found in the Bombyx genome. Despite such differences, dsx homolog of B. mori (Bmdsx) is implicated in the sex determination. Bmdsx produces alternatively spliced mRNA isoforms that encode sex specific transcription factors as observed in dsx. While the female-specific splicing of dsx is activated by splicing activators, Tra and Tra2, the female splicing of Bmdsx represents the default mode. Instead, a splicing inhibitor, BmPSI is involved in the regulation of male-specific splicing of Bmdsx. Since BmPSI does not exhibit any sequence relationship to known SR proteins, such as Tra and Tra2, the regulatory mechanism of sex-specific alternative splicing of Bmdsx is distinct from that of dsx.

Middle-aged heterozygous carriers of Wilson's disease do not present with significant phenotypic deviations related to copper metabolism.

Abstract: Wilson disease (WD) is an autosomal recessive disorder of copper (Cu) metabolism (OMIM 277900 (online Mendelian inheritance in man, URL: http://www.ncbi.nlm. nih.gov/omim/)). The WD gene, ATP7B, is located on chromosome 13 (13q14.3) (Petrukhin et al. 1994) and encodes the copper-transporting P-type ATPase (ATP7B) (OMIM 606882). Over 300 mutations have been described in the ATP7B (http://www.medgen.med.ualberta.ca/database. html). Pathogenic mutation in ATP7B leads to the synthesis of functionally abnormal ATP7B that has a shorter lifetime and/or improper intracellular localization (Forbes and Cox 2000; Huster et al. 2003; Cater et al. 2007). Severe Cu metabolism abnormalities are observed in individuals with pathogenic mutations in both alleles of the ATP7B (Ala et al. 2007; de Bie et al. 2007). This results in accumulation of toxic Cu mainly in the liver and in brain leading to a high spectrum of hepatic and/or neuropsychiatric signs and symptoms (Ala et al. 2007; de Bie et al. 2007; Barbosa et al. 2009). In some instances, slight phenotypic deviations were observed in heterozygous carriers of recessive alleles. In the general population, the frequency of heterozygous carriers of WD (WDHzc) is about 1%–2% (Das and Ray 2006). It seems to be of importance to evaluate if WDHzc are predisposed to any abnormalities in Cu metabolism and, if so, whether these abnormalities are related to any symptomatic manifestations. It has been hypothesized, for example, that WDHzc may be at high risk of developing Parkinson disease (PD) (Johnson 2001). It is known for a long time that studies on the phenotypic effects in WDHzc are difficult because of a high genetic

Association of AFLP and SSR markers with agronomic and fibre quality traits in Gossypium hirsutum L.

Abstract: Molecular markers linked to QTL contributing to agronomic and fibre quality traits would be useful for cotton improvement. We have attempted to tag yield and fibre quality traits with AFLP and SSR markers using F2 and F3 populations of a cross between two Gossypium hirsutum varieties, PS56-4 and RS2013. Out of 50 AFLP primer combinations and 177 SSR primer pairs tested, 32 AFLP and four SSR primers were chosen for genotyping F2 individuals. Marker-trait associations were studied for eight agronomic and five fibre quality traits through simple and multiple regression analysis (MRA) using a set of 92 AFLP polymorphic loci and four SSR markers. Simple linear regression analysis (SLRA) identified 23 markers for eight different traits whereas multiple regression analysis identified 30 markers for at least one of the 13 traits. SSR marker BNL 3502 was consistently identified to be associated with fibre strength. While all the markers identified in SLRA were also detected in MRA, as many as 16 of the 30 markers were identified to be associated with respective traits in both F2 and F3 generations. The markers explained up to 41 per cent of phenotypic variation for individual traits. A number of markers were found to be associated with multiple traits suggesting clustering of QTLs for fibre quality traits in cotton.

Mitochondrial DNA sequence-based phylogenetic relationship among flesh flies of the genus Sarcophaga (Sarcophagidae: Diptera)

Abstract: The phylogenetic relationships among flesh flies of the family Sarcophagidae has been based mainly on the morphology of male genitalia. However, the male genitalic character-based relationships are far from satisfactory. Therefore, in the present study mitochondrial DNA has been used as marker to unravel genetic relatedness and to construct phylogeny among five sympatric species of the genus Sarcophaga. Two mitochondrial genes viz., cytochrome oxidase subunit 1 (COI) and NAD dehydrogenase subunit 5 (ND5) were sequenced and genetic distance values were calculated on the basis of sequence differences in both the mitochondrial genes. The data revealed very few genetic difference among the five species for the COI and ND5 gene sequences.

Exploration of genetic susceptibility factors for Parkinson’s disease in a South American sample

Abstract: 1Neurosciences Research Group, School of Medicine and Institute of Genetics, Universidad Nacional de Colombia, Bogota, Colombia 2Department of Internal Medicine, 3Department of Pediatrics, 4Department of Pathology, School of Medicine, Universidad Nacional de Colombia, Bogota, Colombia 5MSc Program in Neurosciences, Universidad Nacional de Colombia, Bogota, Colombia 6Present address: Biomedical Science Research Group, School of Medicine, Universidad Antonio Narino, Bogota, Colombia

Association of polymorphisms in folate metabolic genes and prostate cancer risk: a case-control study in a Chinese population.

Abstract: Epidemiological studies have shown an association between low folate intake and an increased cancer risk. Folate deficiency is thought to increase the risk of cancer through impaired DNA repair synthesis and disruption of DNA methylation (Duthie 1999; Choi and Mason 2000; Wei et al. 2003; Shen et al. 2005). However, the reports of association between folate status and risk of prostate cancer are conflicting. Figueiredo et al. (2009) reported that daily supplementation with 1 mg of folic acid was associated with an increased risk of prostate cancer in a double-blind randomized clinical trial, whereas Pelucchi et al. (2005) found a significant inverse association between dietary folate and prostate cancer risk in a case–control study. The complex role of folate in prostate carcinogenesis may be due to polymorphisms in genes encoding folate metabolism enzymes. We hypothesized that polymorphisms in key folate metabolism genes may influence the effect of folate on prostate cancer development. Methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR) and methionine synthase reductase (MTRR) play important and interrelated roles in the folate metabolic pathway. MTHFR catalyses the reduction of 5,10-methylenetetrahydrolate to 5-methyltetrahydrofolate, the major circulatory form of folate in the body and a

Conservation and sex-specific splicing of the doublesex gene in the economically important pest species Lucilia cuprina

Abstract: Genetic control of sex determination in insects has been best characterized in Drosophila melanogaster, where the master gene Sxl codes for RNA that is sex specifically spliced to produce a functional protein only in females. SXL regulates the sex-specific splicing of transformer (tra) RNA which, in turn, regulates the splicing of dsx RNA to produce functional male and female proteins. In the Australian sheep blowfly (Lucilia cuprina), the tra gene (Lctra) is required for female development and Lctra transcripts are sex-specifically spliced such that only female Lctra mRNA codes for functional protein. In males, a factor encoded by the Y-linked male determining gene is thought to prevent the female-mode of splicing of Lctra RNA. To further our understanding of the sex determination regulatory hierarchy in L. cuprina, we have isolated the dsx gene (Lcdsx) from this species. We found that the Lcdsx transcripts are sex-specifically spliced in a similar manner as their counterparts in D. melanogaster, housefly and tephritids. The LcDSX proteins are well conserved and the male form of DSX contains a motif encoded by a male-specific exon that is within the female-specific intron. This intron/exon arrangement had previously been found only in the housefly dsx gene, suggesting this may be a unique feature of dsx genes of Calyptratae species.

Modifiers and mechanisms of multi-system polyglutamine neurodegenerative disorders: lessons from fly models

Abstract: Polyglutamine (polyQ) diseases, resulting from a dynamic expansion of glutamine repeats in a polypeptide, are a class of genetically inherited late onset neurodegenerative disorders which, despite expression of the mutated gene widely in brain and other tissues, affect defined subpopulations of neurons in a disease-specific manner. We briefly review the different polyQ-expansion-induced neurodegenerative disorders and the advantages of modelling them in Drosophila. Studies using the fly models have successfully identified a variety of genetic modifiers and have helped in understanding some of the molecular events that follow expression of the abnormal polyQ proteins. Expression of the mutant polyQ proteins causes, as a consequence of intra-cellular and inter-cellular networking, mis-regulation at multiple steps like transcriptional and posttranscriptional regulations, cell signalling, protein quality control systems (protein folding and degradation networks), axonal transport machinery etc., in the sensitive neurons, resulting ultimately in their death. The diversity of genetic modifiers of polyQ toxicity identified through extensive genetic screens in fly and other models clearly reflects a complex network effect of the presence of the mutated protein. Such network effects pose a major challenge for therapeutic applications.

Use of a regulatory mechanism of sex determination in pest insect control.

Abstract: The sexual development of an insect is defined through a hierarchical control of several sex determining genes. Of these genes, transformer (tra) and doublesex (dsx) are well characterized and functionally conserved, especially dsx. Both genes are regulated at the transcriptional level through sex-specific alternative splicing. Incorporation of a genetically engineered sexspecific splicing module derived from these genes in transgenic systems, such as RIDL (release of insects carrying a dominant lethal), would allow the production of male-only insects for control programmes without any physical intervention.

Analysis of genetic diversity in a close population of Zandi sheep using genealogical information

Abstract: In a Fisher–Wright idealized population (Fisher 1930; Wright 1931), characterized by Poisson distribution of family size, large number of breeders, random mating, equal sex ratio, absence of selection, mutation, or migration, and discrete generations, the rate of loss of heterozygosity is inversely proportional to population size. In real populations, however, genetic diversity is affected by several ongoing natural processes of mutation, migration, genetic drift and selection. For this reason, Wright (1931) proposed the concept of the effective population size (Ne) for extending population genetics theory developed for ideal populations to real populations. This parameter has been useful in designing strategies for conservation of endangered animal species because of its direct relationship with the level of inbreeding (Caballero and Toro 2000). However, when Ne is estimated from pedigree data, the parameter accuracy may be affected by several factors, as extensively reviewed by Boichard et al. (1997). Consequently, in recent decades, new complementary techniques have been developed for the analysis of genealogies. Lacy (1989) introduced the concept of effective number of founders ( fe) in order to measure the overall founder representation in a managed population accounting for the loss of genetic diversity from unequal founder contributions, and the concept of founder genome equivalents ( fg), also called effective number of founder genomes, to account the effects of bottlenecks, unequal founder contributions, and genetic drift. Boichard et al. (1997) developed the concept of effective number of ancestors ( fa) to supplement the effective number of founders. The numbers obtained from

Inheritance of flower colour and spinelessness in safflower ( Carthamus tinctorius L.)

Abstract: . 1999).Varieties that are almost completely free of spines havebeen developed for hand harvest of floral parts and of seedsin certain geographic regions (Singh 2007). Hence, one ofthe main goals in safflower breeding programmes is to de-velop spineless varieties with a high yield, high oil content,and resistance to diseases and pests.Morphological markers are usually visually character-ized phenotypic traits such as flower colour and spininess,and are useful for plant breeders. The most important char-acteristics in terms of its ornamental value are a combinationof appealing flower colour and few spines, descriptors thathave been used as major evaluation criteria (Bradley

About females and males: continuity and discontinuity in flies

Abstract: Through the decades of relentless and dedicated studies in Drosophila melanogaster, the pathway that governs sexual development has been elucidated in great detail and has become a paradigm in understanding fundamental cell-fate decisions. However, recent phylogenetic studies show that the molecular strategy used in Drosophila deviates in some important aspects from those found in other dipteran flies and suggest that the Drosophila pathway is likely to be a derivative of a simpler and more common principle. In this essay, I will discuss the evolutionary plasticity of the sex-determining pathway based on studies in the common housefly, Musca domestica. Diversification appears to primarily arise from subtle differences in the regulation of the key switch gene transformer at the top of the pathway. On the basis of these findings I propose a new idea on how the Drosophila pathway may have evolved from a more archetypal system such as in M. domestica. In essence, the arrival of an X counting mechanism mediated by Sex-lethal to compensate for Xlinked gene dose differences set the stage for an intimate coupling of the two pathways. Its precedent recruitment to the dosage compensation pathway allowed for an intervention in the regulation of transformer where it gradually and eventually’ completely substituted for a need of transformer autoregulation.

Molecular systematics and conservation of the langurs and leaf monkeys of South Asia.

Abstract: Numerous morphology-based classification schemes have been proposed for langurs and leaf monkeys of South Asia but there is very little agreement between them. An incorrect classification scheme when used as a basis for biogeographic studies can support erroneous hypotheses. Further, lack of taxonomic resolution will also confound conservation efforts, given that conservation biologists use traditional morphology-based-classification schemes to prioritize species for conservation. Here, I have revisited recent molecular phylogenetic studies done on langurs and leaf monkeys of South Asia. Results from these studies are in turn used to derive a rational and scientific basis for prioritizing species for conservation. Molecular data support the classification of langurs of the Indian subcontinent—Hanuman, Nilgiri and purple-faced langurs—in the genus Semnopithecus, whereas Phayre’s leaf monkey along with other Southeast Asian leaf monkeys form another distinct clade (Trachypithecus). The phylogenetic position of capped and golden langurs remains unresolved. Molecular data suggest that they are closely related to each other but this group might have evolved through past hybridization between Semnopithecus and Trachypithecus. Additionally, genetic data also support the splitting of the so-called Hanuman langurs into at least three species. The scores for taxonomic uniqueness of langurs and leaf monkeys of South Asia were revised using this molecular phylogeny-based classification. According to the revised scores, Phayres leaf monkey and golden langur are priority species for conservation followed by capped and Nilgiri langurs.

Segregation distortion in F2 and doubled haploid populations of temperate japonica rice

Abstract: 1Research Institute of Agricultural Resources, Ishikawa Agricultural College, Nonoichi, Ishikawa 921-8836, Japan 2Faculty of Life and Environmental Science, Shimane University, Matsue, Shimane 690-8504, Japan 3Institute of the Society for Techno-innovation of Agriculture, Forestry and Fisheries, Tsukuba, Ibaraki 305-0854, Japan 4Fukui Agricultural Experiment Station, Ryo-machi, Fukui, Fukui 918-8215, Japan 5National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan 6Present address: Research Faculty of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan 7Present address: National Institute of Crop Science, Tsukuba, Ibaraki 305-8518, Japan 8Present address: Department of Bioscience, Fukui Prefecture University, Matsuoka, Fukui 910-1195, Japan

Allelic variations in Glu-1 and Glu-3 loci of historical and modern Iranian bread wheat (Triticum aestivum L.) cultivars

Abstract: Proline and glutamine-rich wheat seed endosperm proteins are collectively referred to as prolamins. They are comprised of HMW-GSs, LMW-GSs and gliadins. HMW-GSs are major determinants of gluten elasticity and LMW-GSs considerably affect dough extensibility and maximum dough resistance. The inheritance of glutenin subunits follows Mendelian genetics with multiple alleles in each locus. Identification of the banding patterns of glutenin subunits could be used as an estimate for screening high quality wheat germplasm. Here, by means of a two-step 1D-SDS-PAGE procedure, we identified the allelic variations in high and low-molecular-weight glutenin subunits in 65 hexaploid wheat (Triticum aestivum L.) cultivars representing a historical trend in the cultivars introduced or released in Iran from the years 1940 to 1990. Distinct alleles 17 and 19 were detected for Glu-1 and Glu-3 loci, respectively. The allelic frequencies at the Glu-1 loci demonstrated unimodal distributions. At Glu-A1, Glu-B1 and Glu-D1, we found that the most frequent alleles were the null, 7 + 8, 2 + 12 alleles, respectively, in Iranian wheat cultivars. In contrast, Glu-3 loci showed bimodal or trimodal distributions. At Glu-A3, themost frequent alleles were c and e. At Glu-B3 the most frequent alleles were a, b and c. At Glu-D3 locus, the alleles b and a, were the most and the second most frequent alleles in Iranian wheat cultivars. This led to a significantly higher Nei coefficient of genetic variations in Glu-3 loci (0.756) as compared to Glu-1 loci (0.547). At Glu-3 loci, we observed relatively high quality alleles in Glu-A3 and Glu-D3 loci and low quality alleles at Glu-B3 locus.

Genetic diversity and population structure of 10 Chinese indigenous egg-type duck breeds assessed by microsatellite polymorphism

Abstract: The genetic structure and diversity of 10 Chinese indigenous egg-type duck breeds were investigated using 29 microsatellite markers. The total number of animals examined were 569, on average 57 animals per breed were selected. The microsatellite marker set analysed provided 177 alleles (mean 6.1 alleles per locus, ranging from 3 to 10). All populations showed high levels of heterozygosity with the lowest estimate of 0.539 for the Jinding ducks, and the highest 0.609 observed for Jingjiang partridge ducks. The global heterozygote deficit across all populations (FIT) amounted to −0.363. About 10% of the total genetic variability originated from differences among breeds, with all loci contributing significantly. An unrooted consensus tree was constructed using the NeighborNet tree based on the Reynold’s genetic distance. The structure software was used to assess genetic clustering of these egg-type duck breeds. Clustering analysis provided an accurate representation of the current genetic relations among the breeds. An integrated analysis was undertaken to obtain information on the population dynamics in Chinese indigenous egg-type duck breeds, and to better determine the conservation priorities.

Molecular analysis of Albizia species using AFLP markers for conservation strategies

Abstract: Improving commercial and ecological utilization of the perennial tree legume, genus Albizia, requires developing approaches that can accurately characterize genetic variation in its gene pool. Amplified fragment length polymorphism (AFLP) markers, in combination with morphological traits, have been used to ascertain the extent of genetic diversity and relatedness among the nine Albizia species. The variations observed among the Albizia species for seven morphological traits were summarized by means of discriminant analysis. Four significant variables, accounting for about 96.1% of total variance, were mainly correlated with plant height, number of pinnae, number of leaflet per pinnae and leaflet size. The morphological variations appeared to be related to the molecular variations. AFLP analysis of nine Albizia species based on 12 primer pair combinations revealed a total of 724 polymorphic-amplified DNA fragments. The genetic similarities estimated among the nine Albizia species, based on both shared and unique amplification products, ranged from 0.51 to 0.73 across all species. Both morphological and molecular data will be an important input to determine the appropriate management strategies for conservation and improvement of the breeding programme for this genus. The genus Albizia belongs to subfamily Mimoseae of family Leguminosae and is highly valued multipurpose tree legume. The legume tree species have been severely diminished by logging, immense human pressure, overexploitation and land clearance. Many Albizia species are endemic to Indian subcontinent. The Indian species A. thomsonii are classified as vulnerable (Nayar and Sastry 1990). Albizia species are socially significant for producing high quality timber and as a valuable resource for gum yield. Albizia julibrissin, A. lebbeck, A. procera and A. amara are important in ayruvedic medicine. Seeds are

The role of the Drosophila LAMMER protein kinase DOA in somatic sex determination.

Abstract: DOA kinase, the Drosophila member of the LAMMER/Clk protein kinase family, phosphorylates SR and SR-like proteins, including TRA, TRA2 and RBP1, which are responsible for the alternative splicing of transcripts encoding the key regulator of sex-specific expression in somatic cells of the fly, DOUBLESEX. Specific Doa alleles induce somatic female-to-male sex transformations, which can be enhanced when combined with mutations in loci encoding SR and SR-like proteins. The Doa locus encodes six different kinases, of which a 69-kDa isoform is expressed solely in females. Expression of this isoform is itself under the regulation of the somatic sex determination regulatory network, thus forming a putative positive autoregulatory loop which would reinforce the choice of the female cell-fate. We speculate that this loop is part of the evolutionary ancestral sex-determination machinery, based upon evidence demonstrating the existence of an autoregulatory loop involving TRA and TRA2 in several other insect species.

Genetic fingerprint of microorganisms associated with the deterioration of an historical tuff monument in Italy.

Abstract: Monuments, works of art, and other cultural heritage are affected by microbial colonization that can, together with physical and chemical factors, cause serious structural and aesthetic damage. This is because cultural artifacts provide an inviting range of elements which microorganisms use in their metabolism through biosolubilization, e.g., elements such as calcium, aluminum, silicon, iron and potassium. Microorganisms can induce unsightly discolouration of building material and frescoes, formation of pigmented biofilms, biomineralization and degradation of organic binders leading to structural damage (Herrera et al. 2004). Microbial solubilization of materials involves the production of organic and inorganic acids by metabolic activity and is one of the leading biogeochemical mechanisms of rock decay. The bioreceptivity of a stone depends on its structure and chemical composition, air pollutants, moisture, and the varied elemental compositions of the stones provide a suitable environment for the microorganisms to develop. Moreover, phototrophic microorganisms may grow on the stone surface or may penetrate some millimetres into the rock pore system. These organisms can potentially contribute to the breakdown of rock crystalline structures. With time, the developing microorganisms cause the deterioration of the stones on which they reside by secreting enzymes and activating other metabolic activities by providing a suitable medium for their growth on the stone pores and surfaces (Dornieden et al. 2000; Warscheid and Braams 2000).