Eye colour as a genetic marker for fertility and fecundity of Triatoma infestans (Klug, 1834) Hemiptera, Reduviidae, Triatominae

Eye colour of Triatoma infestans is controlled at a single autosomal locus, with black-eye as the dominant gene and red-eye as the recessive. Inheritance of these characters follows a classical Mendelian system, enabling eye colour to be used as a marker for studies of mating frequency. We found no significant differences in oviposition rates and egg hatching rates irrespective of parental phenotypes. Different mating schedules between red-eye and black-eye parents showed that eye colour did not affect mating competence. Females mated with a single male or with different males together or in succession produced similar numbers of fertile eggs, with the eye colour of the offspring reflecting exposure to the different males. We conclude that although a single mating can provide sufficient sperm for the whole reproductive life of the female, multiple matings can result in balanced assortative sperm usage from the spermatheca.

Identification of a genetic marker associated with the resistance to Schistosoma mansoni infection using random amplified polymorphic DNA analysis

In schistosomiasis, the host/parasite interaction remains not completely understood. Many questions related to the susceptibility of snails to infection by respective trematode still remain unanswered. The control of schistosomiasis requires a good understanding of the host/parasite association. In this work, the susceptibility/resistance to Schistosoma mansoni infection within Biomphalaria alexandrina snails were studied starting one month post infection and continuing thereafter weekly up to 10 weeks after miracidia exposure. Genetic variations between susceptible and resistant strains to Schistosoma infection within B. alexandrina snails using random amplified polymorphic DNA analysis technique were also carried out. The results showed that 39.8% of the examined field snails were resistant, while 60.2% of these snails showed high infection rates.In the resistant genotype snails, OPA-02 primer produced a major low molecular weight marker 430 bp. Among the two snail strains there were interpopulational variations, while the individual specimens from the same snail strain, either susceptible or resistant, record semi-identical genetic bands. Also, the resistant character was ascendant in contrast to a decline in the susceptibility of snails from one generation to the next.

Evaluaton of a genetic marker within the organ of Corti of transgenic mice

This paper reviews a study to evaluate a genetic marker within the organ of Corti in transgenic mice for potential use in cell lineage studies.

Large-scale transcriptome analyses reveal new genetic marker candidates of head, neck, and thyroid cancer

A detailed genome mapping analysis of 213,636 expressed sequence tags (EST) derived from nontumor and tumor tissues of the oral cavity, larynx, pharynx, and thyroid was done. Transcripts matching known human genes were identified; potential new splice variants were flagged and subjected to manual curation, pointing to 788 putatively new alternative splicing isoforms, the majority (75%) being insertion events. A subset of 34 new splicing isoforms (5% of 788 events) was selected and 23 (68%) were confirmed by reverse transcription-PCR and DNA sequencing. Putative new genes were revealed, including six transcripts mapped to well-studied chromosomes such as 22, as well as transcripts that mapped to 253 intergenic regions. In addition, 2,251 noncoding intronic RNAs, eventually involved in transcriptional regulation, were found. A set of 250 candidate markers for loss of heterozygosis or gene amplification was selected by identifying transcripts that mapped to genomic regions previously known to be frequently amplified or deleted in head, neck, and thyroid tumors. Three of these markers were evaluated by quantitative reverse transcription-PCR in an independent set of individual samples. Along with detailed clinical data about tumor origin, the information reported here is now publicly available on a dedicated Web site as a resource for further biological investigation. This first in silico reconstruction of the head, neck, and thyroid transcriptomes points to a wealth of new candidate markers that can be used for future studies on the molecular basis of these tumors. Similar analysis is warranted for a number of other tumors for which large EST data sets are available.

Human Platelet Polymorphism can be a genetic marker associated with HIV/HCV coinfection

To evaluate the associations of HPA polymorphisms -1, -3, and -5 with HIV/HCV coinfection were included in this study 60 HIV/HCV-coinfected patients from the Sao Paulo State health service centers. Data reported by Verdichio-Moraes et al. (2009: J. Med Virol 81:757-759) were used as the non-infected and HCV monoinfected groups. Human Platelet Polymorphism genotyping was performed in 60 Patients co-infected with HIV/HCV by PCR-SSP or PCR-RFLP. HIV subtyping and HCV genotyping was performed by RT-PCR followed sequencing. The data analyses were performed using the χ2 test or Fisher's Exact Test and the logistic regression model. Patients coinfected with HIV/HCV presented HCV either genotype 1 (78.3%) or non-1 (21.7%) and HIV either subtype B (85.0%) or non-B (15%). The Human Platelet Polymorphism-1a/1b genotype was more frequent (P < 0.05) in HIV/HCV coinfection than in HCV monoinfection and the allelic frequency of Human Platelet Polymorphism-5b in the Patients coinfected with HIV/HCV was higher (P < 0.05) than in HCV monoinfected cases and non-infected individuals. These data suggest that the presence of specific HPA allele on platelets could favor the existence of coinfection. On the other hand, Human Platelet Polymorphism-5a/5b was more frequent (P < 0.05) in HIV/HCV coinfected and HCV monoinfected groups than in the non-infected individuals, suggesting that this platelet genotype is related to HCV infection, regardless of HIV presence. Results suggest that the Human Platelet Polymorphism profile in HIV/HCV coinfected individuals differs from the one of both HCV monoinfected and non-infected population. So, the Human Platelet Polymorphism can be a genetic marker associated with HIV/HCV coinfection.

Alcohol dehydrogenase 1C*1 allele is a genetic marker for alcohol-associated cancer in heavy drinkers

Chronic alcohol consumption is associated with an increased risk for upper aerodigestive tract cancer and hepatocellular carcinoma. Increased acetaldehyde production via alcohol dehydrogenase (ADH) has been implicated in the pathogenesis. The allele ADH1C*1 of ADH1C encodes for an enzyme with a high capacity to generate acetaldehyde. So far, the association between the ADH1C*1 allele and alcohol-related cancers among heavy drinkers is controversial. ADH1C genotypes were determined by polymerase chain reaction and restriction fragment length polymorphism in a total of 818 patients with alcohol-associated esophageal (n=123), head and neck (n=84) and hepatocellular cancer (n=86) as well as in patients with alcoholic pancreatitis (n=117), alcoholic liver cirrhosis (n=217), combined liver cirrhosis and pancreatitis (n=17) and in alcoholics without gastrointestinal organ damage (n=174). The ADH1C*1 allele and genotype ADH1C*1/1 were significantly more frequent in patients with alcohol-related cancers than that in individuals with nonmalignant alcohol-related organ damage. Using multivariate analysis, ADH1C*1 allele frequency and rate of homozygosity were significantly associated with an increased risk for alcohol-related cancers (p<0.001 in all instances). The odds ratio for genotype ADH1C*1/1 regarding the development of esophageal, hepatocellular and head and neck cancer were 2.93 (CI, 1.84-4.67), 3.56 (CI, 1.33-9.53) and 2.2 (CI, 1.11-4.36), respectively. The data identify genotype ADH1C*1/1 as an independent risk factor for the development of alcohol-associated tumors among heavy drinkers, indicating a genetic predisposition of individuals carrying this genotype.

A GENETIC MARKER STUDY OF NON - INSULIN DEPENDENT DIABETICS IN THE MEXICAN-AMERICAN COMMUNITY FROM STARR COUNTY, TEXAS (PLASMA GLUCOSE, HEMOGLOBIN ANALYSIS)

Diabetes mellitus occurs in two forms, insulin-dependent (IDDM, formerly called juvenile type) and non-insulin dependent (NIDDM, formerly called adult type). Prevalence figures from around the world for NIDDM, show that all societies and all races are affected; although uncommon in some populations (.4%), it is common (10%) or very common (40%) in others (Tables 1 and 2).^ In Mexican-Americans in particular, the prevalence rates (7-10%) are intermediate to those in Caucasians (1-2%) and Amerindians (35%). Information about the distribution of the disease and identification of high risk groups for developing glucose intolerance or its vascular manifestations by the study of genetic markers will help to clarify and solve some of the problems from the public health and the genetic point of view.^ This research was designed to examine two general areas in relation to NIDDM. The first aims to determine the prevalence of polymorphic genetic markers in two groups distinguished by the presence or absence of diabetes and to observe if there are any genetic marker-disease association (univariate analysis using two by two tables and logistic regression to study the individual and joint effects of the different variables). The second deals with the effect of genetic differences on the variation in fasting plasma glucose and percent glycosylated hemoglobin (HbAl) (analysis of Covariance for each marker, using age and sex as covariates).^ The results from the first analysis were not statistically significant at the corrected p value of 0.003 given the number of tests that were performed. From the analysis of covariance of all the markers studied, only Duffy and Phosphoglucomutase were statistically significant but poor predictors, given that the amount they explain in terms of variation in glycosylated hemoglobin is very small.^ Trying to determine the polygenic component of chronic disease is not an easy task. This study confirms the fact that a larger and random or representative sample is needed to be able to detect differences in the prevalence of a marker for association studies and in the genetic contribution to the variation in glucose and glycosylated hemoglobin. The importance that ethnic homogeneity in the groups studied and standardization in the methodology will have on the results has been stressed. ^

Isolation and characterization of a pseudoautosomal region-specific genetic marker in C57BL/6 mice using genomic representational difference analysis.

Representational difference analysis was used to identify strain-specific differences in the pseudoautosomal region (PAR) of mouse X and Y chromosomes. One second generation (C57BL/6 x Mus spretus) x Mus spretus interspecific backcross male carrying the C57BL/6 (B6) PAR was used for tester DNA. DNA from five backcross males from the same generation that were M. spretus-type for the PAR was pooled for the driver. A cloned probe designated B6-38 was recovered that is B6-specific in Southern analysis. Analysis of genomic DNA from several inbred strains of laboratory mice and diverse Mus species and subspecies identified a characteristic Pst I pattern of fragment sizes that is present only in the C57BL family of strains. Hybridization was observed with sequences in DBA/2J and to a limited extent with Mus musculus (PWK strain) and Mus castaneus DNA. No hybridization was observed in DNA of different Mus species, M. spretus, M. hortulanus, and M. caroli. Genetic analyses of B6-38 was conducted using C57BL congenic males that carry M. spretus alleles for distal X chromosome loci and the PAR and outcrosses of heterozygous congenic females with M. spretus. These analyses demonstrated that the B6-38 sequences were inherited with both the X and Y chromosome. B6-38 sequences were genetically mapped as a locus within the PAR using two interspecific backcrosses. The locus defined by B6-38 is designated DXYRp1. Preliminary analyses of recombination between the distal X chromosome gene amelogenin (Amg) and the PAR loci for either TelXY or sex chromosome association (Sxa) suggest that the locus DXYRp1 maps to the distal portion of the PAR.

WW6: an embryonic stem cell line with an inert genetic marker that can be traced in chimeras.

Mutant mice produced by gene targeting in embryonic stem (ES) cells often have a complex or embryonic lethal phenotype. In these cases, it would be helpful to identify tissues and cell types first affected in mutant embryos by following the contribution to chimeras of ES cells homozygous for the mutant allele. Although a number of strategies for following ES cell development in vivo have been reported, each has limitations that preclude its general application. In this paper, we describe ES cell lines that can be tracked to every nucleated cell type in chimeras at all developmental stages. These lines were derived from blastocysts of mice that carry an 11-Mb beta-globin transgene on chromosome 3. The transgene is readily detected by DNA in situ hybridization, providing an inert, nuclear-localized marker whose presence is not affected by transcriptional or translational controls. The "WW" series of ES lines possess the essential features of previously described ES lines, including giving rise to a preponderance of male chimeras, all of which have to date exhibited germ-line transmission. In addition, clones selected for single or double targeting events form strong chimeras, demonstrating the feasibility of using WW6 cells to identify phenotypes associated with the creation of a null mutant.

A Genetic Marker to Separate Emiliania Huxleyi (Prymnesiophyceae) Morphotypes

Emiliania huxleyi (Lohm.) Hay and Mohler is a ubiquitous unicellular marine alga surrounded by an elaborate covering of calcite platelets called coccoliths. It is an important primary producer involved in oceanic biogeochemistry and climate regulation. Currently, E. huxleyi is separated into five morphotypes based on morphometric, physiological, biochemical, and immunological differences. However, a genetic marker has yet to be found to characterize these morphotypes. With the use of sequence analysis and denaturing gradient gel electrophoresis, we discovered a genetic marker that correlates significantly with the separation of the most widely recognized A and B morphotypes. Furthermore, we reveal that the A morphotype is composed of a number of distinct genotypes. This marker lies within the 3' untranslated region of a coccolith associated protein mRNA, which is implicated in regulating coccolith calcification. Consequently, we tentatively termed this marker the coccolith morphology motif.

Is ITS-2 rDNA suitable marker for genetic characterization of Sarcoptes mites from different wild animals in different geographic areas?

The present study examined the relationship among individual Sarcoptes scabiei mites from 13 wild mammalian populations belonging to nine species in four European countries using the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA (rDNA) as genetic marker. The ITS-2 plus primer flanking 5.8S and 28S rDNA (ITS-2+) was amplified from individual mites by polymerase chain reaction (PCR) and the amplicons were sequenced directly. A total of 148 ITS-2+ sequences of 404bp in length were obtained and 67 variable sites were identified (16.59%). UPGMA analyses did not show any geographical or host-specific clustering, and a similar outcome was obtained using population pairwise Fst statistics. These results demonstrated that ITS-2 rDNA does not appear to be suitable for examining genetic diversity among mite populations.

HLA-DRB1*allele-associated genetic susceptibility and protection against multiple sclerosis in Brazilian patients

Multiple sclerosis (MS) is a chronic autoimmune demyelinating disease of the central nervous system that causes neurological disorders in young adults. Previous studies in various populations highlighted an association between the HLA-DRB1*1.5 allele and MS. This study investigated the association between HLA-DRB1*15 and other HLA-DRB1 alleles and MS in a Brazilian Caucasian population sample from Londrina, Southern Brazil. HLA-DRB1 alleles were analyzed by polymerase chain reaction with specific sequence oligonucleotide primers in 119 MS patients and in 305 healthy blood donors as a control. Among the MS patients, 89 (75.0%) presented with relapsing remitting MS, 24 (20.0%) with secondary progressive MS and 6 (5.0%) with primary progressive MS. The frequency of the HLA-DRB1*15 allele observed in the MS Brazilian patients was similar to findings reported in previous studies carried out in populations worldwide. However, the results showed a higher frequency of the HLA-DRB1*15 allele in the MS patients compared to the controls, with a relative frequency of 0.1050 (10.50%) and 0.0443 (4.4%), respectively (OR=2.53; 95% CI 1.43-4.46; p=0.0009). A protector allele was also detected. The frequency of the HLA-DRB1*11 allele was reduced in the MS patients compared to the controls, with a relative frequency of 0.1345 (13.4%) and 0.1869 (18.7%), respectively (OR=0.67; 95% CI 0.44-1.03; p=0.0692). The results demonstrated that the HLA-DRB1*15 allele in heterozygosity is positively associated with MS (p=0.0079), and may be considered a genetic marker of susceptibility to the disease. A negative association between the HLA-DRB1*11 allele in homozygosity and MS was also verified (p=0.0418); this allele may be considered a genetic marker of resistance to MS in the Brazilian population.

Human leukocyte antigen (HLA) and single nucleotide polymorphisms (SNPs) tumor necrosis factor (TNF)-alpha-238 and-308 as genetic markers of susceptibility to psoriasis and severity of the disease in a long-term follow-up Brazilian study

Background The strongest genetic marker for psoriasis is Cw*06. Polymorphisms in the tumor necrosis factor (TNF)-alpha promoter region, especially replacement of guanine with adenine in positions -238 and -308 are related to higher TNF-alpha production and higher risk for psoriasis in Caucasoid populations, not found in Asians. We performed a case-control study of 69 patients with psoriasis type I and 70 controls, characterized clinical progression along 10-years of follow-up in mild or severe disease and determined HLA class I, II, and TNF single nucleotide polymorphisms (SNPs) -238 and -308 polymorphisms to demonstrate whether these polymorphisms may be genetic risk for susceptibility to psoriasis or severity of the disease in Brazilians. Methods Polymorphisms were identified using PCR/SSP. Alleles, genotypes, and haplotypes frequencies were compared using Fisher`s test. Results More severe disease was found in male patients. It may be suggested that alleles B*37, Cw*06, Cw*12, and DRB1*07 were associated with severe disease course, while B*57 with mild disease. No statistical difference was found between the patients and controls regarding polymorphisms frequencies in TNF SNPs. This study pointed to a higher TNF-238 G/G genotype frequency (OR: 3.21; CI: 1.06-9.71; P = 0.04) in the group with severe disease. Conclusions Polymorphisms in the TNF-alpha SNPs do not seem to be a more important genetic risk factor for psoriasis than the already known Cw*06 in Brazilian patients, but these markers may be related to clinical manifestations.