A new and distinctive male-sterile, female-fertile desynaptic mutant in soybean (Glycine max).

A spontaneous desynaptic mutation, affecting only microsporogenesis and causing pollen sterility, has been detected in BR97-12986H, a line of the official Brazilian soybean breeding program. In this male-sterile, female-fertile mutant, up to metaphase II, the meiotic behavior was similar to that described for the st series of synaptic mutants previously reported in soybean. Besides many univalents, few or total absence of bivalents were recorded in diakinesis. Bivalents presented one or two terminal chiasmata, while univalents retained the sister chromatid cohesion. Bivalents and most univalents congregated at the equatorial metaphase plate, although univalents frequently migrated to the poles prematurely. Laggards resulting from delay in chiasmata terminalization were also recorded. Distinctly different in their behavior from st series soybean mutants, telophase I-originated micronuclei of different sizes organized their own spindle in the second division. This behavior contributed towards an increase in genome fractionation. Several microspores and microcytes of different sizes were recorded at the end of meiosis. Pollen sterility was estimated at 91.2 %. Segregation ratio for sterility in this line and its progenies reached 3:1. Allelism tests with st series of synaptic mutants are in progress. The importance of male-sterile, female-fertile mutations for soybean breeding programs is discussed

Meiotic behavior of the Brazilian table grape cultivar Rubi (Vitis vinifera) with a high proportion of seedless berries

Meiotic behavior, pollen fertility and germination of the Brazilian table grape cv, Rubi (Vitis vinifera) were investigated; this cultivar produced different numbers of seedless berries when cultivated at two different sites: At site A vines produced a high proportion of seedless berries while at site B vines produced berries with a normal number of seeds. Cytological analysis of inflorescences collected from the two sites showed some meiotic abnormalities, the most common being related to chromosomal segregation and telophase micronuclei formation leading to microcyte formation in the tetrads, Cytoplasmic channels, bridges and tripolar spindles were also observed in some microsporocytes, Pollen fertility was high at both sites, approximately 96 % at site A and 98 % at site B, The rate of pollen germination was lower at site A than at site B, suggesting that the absence of seed formation is related to pollen germination rate.

Alternative Splicing Changes Promoted by NOVA2 Upregulation in Endothelial Cells and Relevance for Gastric Cancer

Angiogenesis is crucial for cancer progression. While several anti-angiogenic drugs are in use for cancer treatment, their clinical benefits are unsatisfactory. Thus, a deeper understanding of the mechanisms sustaining cancer vessel growth is fundamental to identify novel biomarkers and therapeutic targets. Alternative splicing (AS) is an essential modifier of human proteome diversity. Nevertheless, AS contribution to tumor vasculature development is poorly known. The Neuro-Oncological Ventral Antigen 2 (NOVA2) is a critical AS regulator of angiogenesis and vascular development. NOVA2 is upregulated in tumor endothelial cells (ECs) of different cancers, thus representing a potential driver of tumor blood vessel aberrancies. Here, we identified novel AS transcripts generated upon NOVA2 upregulation in ECs, suggesting a pervasive role of NOVA2 in vascular biology. In addition, we report that NOVA2 is also upregulated in ECs of gastric cancer (GC), and its expression correlates with poor overall survival of GC patients. Finally, we found that the AS of the Rap Guanine Nucleotide Exchange Factor 6 (RapGEF6), a newly identified NOVA2 target, is altered in GC patients and associated with NOVA2 expression, tumor angiogenesis, and poor patient outcome. Our findings provide a better understanding of GC biology and suggest that AS might be exploited to identify novel biomarkers and therapeutics for anti-angiogenic GC treatments

Comparative cytogenetics of three species of Dichotomius (Coleoptera, Scarabaeidae)

Meiotic and mitotic chromosomes of Dichotomius nisus, D. semisquamosus and D. sericeus were analyzed after conventional staining, C-banding and silver nitrate staining. In addition, Dichotomius nisus and D. semisquamosus chromosomes were also analyzed after fluorescent in situ hybridization (FISH) with an rDNA probe. The species analyzed had an asymmetrical karyotype with 2n = 18 and meta-submetacentric chromosomes. The sex determination mechanism was of the Xyp type in D. nisus and D. semisquamosus and of the Xy r type in D. sericeus. C-banding revealed the presence of pericentromeric blocks of constitutive heterochromatin (CH) in all the chromosomes of the three species. After silver staining, the nucleolar organizer regions (NORs) were located in autosomes of D. semisquamosus and D. sericeus and in the sexual bivalent of D. nisus. FISH with an rDNA probe confirmed NORs location in D. semisquamosus and in D. nisus. Our results suggest that chromosome inversions and fusions occurred during the evolution of the group

Chronic Replication Problems Impact Cell Morphology and Adhesion of DNA Ligase I Defective Cells

Moderate DNA damage resulting from metabolic activities or sub-lethal doses of exogenous insults may eventually lead to cancer onset. Human 46BR.1G1 cells bear a mutation in replicative DNA ligase I (LigI) which results in low levels of replication-dependent DNA damage. This replication stress elicits a constitutive phosphorylation of the ataxia telangiectasia mutated (ATM) checkpoint kinase that fails to arrest cell cycle progression or to activate apoptosis or cell senescence. Stable transfection of wild type LigI, as in 7A3 cells, prevents DNA damage and ATM activation. Here we show that parental 46BR.1G1 and 7A3 cells differ in important features such as cell morphology, adhesion and migration. Comparison of gene expression profiles in the two cell lines detects Bio-Functional categories consistent with the morphological and migration properties of LigI deficient cells. Interestingly, ATM inhibition makes 46BR.1G1 more similar to 7A3 cells for what concerns morphology, adhesion and expression of cell-cell adhesion receptors. These observations extend the influence of the DNA damage response checkpoint pathways and unveil a role for ATM kinase activity in modulating cell biology parameters relevant to cancer progression

Lamin A/C truncation in dilated cardiomyopathy with conduction disease

BACKGROUND: Mutations in the gene encoding the nuclear membrane protein lamin A/C have been associated with at least 7 distinct diseases including autosomal dominant dilated cardiomyopathy with conduction system disease, autosomal dominant and recessive Emery Dreifuss Muscular Dystrophy, limb girdle muscular dystrophy type 1B, autosomal recessive type 2 Charcot Marie Tooth, mandibuloacral dysplasia, familial partial lipodystrophy and Hutchinson-Gilford progeria. METHODS: We used mutation detection to evaluate the lamin A/C gene in a 45 year-old woman with familial dilated cardiomyopathy and conduction system disease whose family has been well characterized for this phenotype [1]. RESULTS: DNA from the proband was analyzed, and a novel 2 base-pair deletion c.908_909delCT in LMNA was identified. CONCLUSIONS: Mutations in the gene encoding lamin A/C can lead to significant cardiac conduction system disease that can be successfully treated with pacemakers and/or defibrillators. Genetic screening can help assess risk for arrhythmia and need for device implantation

Investigation of KIT gene mutations in women with 46,XX spontaneous premature ovarian failure

BACKGROUND: Spontaneous premature ovarian failure presents most commonly with secondary amenorrhea. Young women with the disorder are infertile and experience the symptoms and sequelae of estrogen deficiency. The mechanisms that give rise to spontaneous premature ovarian failure are largely unknown, but many reports suggest a genetic mechanism in some cases. The small family size associated with infertility makes genetic linkage analysis studies extremely difficult. Another approach that has proven successful has been to examine candidate genes based on known genetic phenotypes in other species. Studies in mice have demonstrated that c-kit, a transmembrane tyrosine kinase receptor, plays a critical role in gametogenesis. Here we test the hypothesis that human KIT mutations might be a cause of spontaneous premature ovarian failure. METHODS AND RESULTS: We examined 42 women with spontaneous premature ovarian failure and found partial X monosomy in two of them. In the remaining 40 women with known 46,XX spontaneous premature ovarian failure we evaluated the entire coding region of the KIT gene. We did this using polymerase chain reaction based single-stranded conformational polymorphism analysis and DNA sequencing. We did not identify a single mutation that would alter the amino acid sequence of the c-KIT protein in any of 40 patients (upper 95% confidence limit is 7.2%). We found one silent mutation at codon 798 and two intronic polymorphisms. CONCLUSION: Mutations in the coding regions of the KIT gene appear not to be a common cause of 46,XX spontaneous premature ovarian failure in North American women

Barth syndrome mutations that cause tafazzin complex lability

Complexes containing tafazzin, which remodels newly synthesized cardiolipin, are destabilized by mutations associated with Barth syndrome