Non-lethal Candida albicans cph1/cph1 efg1/efg1 mutant partially protects mice from systemic infections by lethal wild-type cells

Although Candida albicans cph1/cph1 efg1/efg1 mutant cells are not lethal to mice, they proliferated in infected mice instead of simply being cleared by the host immune system. Here, we have shown that the cph1/cph1 efg1/efg1 mutant partially protects mice from systemic infections by the lethal wild-type Candida albicans cells. Our results further indicate that a second dose of the cph1/cph1 efg1/efg1 mutant did not boost the degree of protection.     

Conditional inactivation of Brca1 in the mouse ovarian surface epithelium results in an increase in preneoplastic changes

Epithelial ovarian cancer (EOC) is thought to arise from the ovarian surface epithelium (OSE); however, the molecular events underlying this transformation are poorly understood. Germline mutations in the BRCA1 tumor suppressor gene result in a significantly increased risk of developing EOC and a large proportion of sporadic EOCs display some sort of BRCA1 dysfunction. Using mice with conditional expression of Brca1, we inactivated Brca1 in the murine OSE and demonstrate that this inactivation results in the development of preneoplastic changes, such as hyperplasia, epithelial invaginations, and inclusion cysts, which arise earlier and are more numerous than in control ovaries. These changes resemble the premalignant lesions that have been reported in human prophylactic oophorectomy specimens from women with BRCA1 germline mutation. We also report that inactivation of Brca1 in primary cultures of murine OSE cells leads to a suppression of proliferation due to increased apoptosis that can be rescued by concomitant inactivation of p53. These observations, along with our finding that these cells display an increased sensitivity to the DNA-damaging agent cisplatin, indicate that loss of function of Brca1 in OSE cells impacts both cellular growth control and DNA-damage repair which results in altered cell behavior manifested as morphological changes in vivo that arise earlier and are more numerous than what can be attributed to ageing.     

Eya1 acts upstream of Tbx1, Neurogenin 1, NeuroD and the neurotrophins BDNF and NT-3 during inner ear development

Cell fate specification during inner ear development is dependent upon regional gene expression within the otic vesicle. One of the earliest cell fate determination steps in this system is the specification of neural precursors, and regulators of this process include the Atonal-related basic helix-loop-helix genes, Ngn1 and NeuroD and the T-box gene, Tbx1. In this study we demonstrate that Eya1 signaling is critical to the normal expression patterns of Tbx1, Ngn1, and NeuroD in the developing mouse otocyst. We discuss a potential mechanism for the absence of neural precursors in the Eya1-/- inner ears and the primary and secondary mechanisms for the loss of cochleovestibular ganglion cells in the Eya1bor/bor hypomorphic mutant.     

Genetic analysis of OCT1 gene polymorphisms in an Indian population

BACKGROUND:

Genetic variants of the organic cation transporter (OCT1) gene could influence interindividual variation in clinical response to metformin therapy. The genetic basis for the single-nucleotide polymorphism (SNP) of OCT1 gene has been established in other populations, but it remains to be elucidated in the Indian population. This study is focused on OCT1 gene variants rs2282143 (P341L, 1022C>T), rs628031 (M408V, 1222A>G) and rs622342 (1386C>A) frequency distributions in the South Indian Tamilian population.

MATERIALS AND METHODS:

A total of 112 unrelated healthy subjects of South Indian Tamilian origin, aged 18–60 years, of either sex were recruited for the study. Genotyping was determined using the quantitative real time-polymerase chain reaction and polymerase chain reaction followed by restriction fragment length polymorphism methods.

RESULTS:

Allele frequencies of rs2282143, rs628031and rs622342 polymorphisms were 8.9%, 80.3% and 24.5%, respectively. Interethnic differences in the genotype and allele frequencies of OCT1 gene polymorphism were observed when compared with other major populations. The SNPs rs2282143, T allele and rs628031, G allele were more common in Asians (5.5–16.8% and 76.2–81%) and African Americans (8.2% and 73.5%) than in Caucasians (0–2% and 57.4–60%).

CONCLUSION:

This is the first time the frequency of OCT1 gene polymorphism was determined in the Indian population, and is similar to the frequencies observed in African-Americans and other Asian populations but different from those in Caucasians. The data observed in this study would justify further pharmacogenetic studies to potentially evaluate the role of OCT1 gene polymorphism in the therapeutic efficacy of metformin.     

Genetic interaction of Gsc and Dkk1 in head morphogenesis of the mouse

Mouse embryos lacking Gsc and Dkk1 function display severe deficiencies in craniofacial structures which are not found in either Dkk1 homozygous null or Gsc homozygous null mutant embryos. Loss of Gsc has a dosage-related effect on the severity of head truncation phenotype in Dkk1 heterozygous embryos. The synergistic effect of these mutations in enhancing head truncation provides direct evidence of a genetic interaction between Gsc and Dkk1, which display overlapping expression in the prechordal mesoderm. In the absence of Gsc activity, the expression of Dkk1, WNT genes and a transgenic reporter for WNT signalling are altered. Our results show that Gsc and Dkk1 functions are non-redundant in the anterior mesendoderm for normal anterior development and Gsc may influence Wnt signalling as a negative regulator.     

Tritrichomonas foetus: experimental infection in pregnant BALB/c mice

Bovine genital tritrichomonosis is a venereal disease produced by the flagellate Tritrichomonas foetus. The disease is characterized by the repetition of oestrus and infertility due to embryonic or foetal death. Numerous experimental rodent models have been developed, but none of them has been applied in pregnant females. In this work, we reproduced genital tritrichomonosis in pregnant BALB/c mice. The results were analysed considering the following pregnancy phases: early, middle and final. In the infected group, embryonic loss was significantly higher and occurred in the early and middle phases, in accordance with the time of embryo death in infected bovines. In infected animals at the early phase of pregnancy there was evidence of embryonic death without inflammatory changes in the uterus, suggesting a pathogenic mechanism that does not involve direct tissue damage. In the later days, conceptus loss was associated with endometritis and changes in the decidua.     

Both mating types in the heterothallic fungus Ophiostoma quercus contain MAT1-1 and MAT1-2 genes

In heterothallic Ascomycota, two opposite but distinct mating types control all sexual processes. Using mating crosses, mating types were assigned to ten isolates of the heterothallic fungal species Ophiostoma quercus. Primers were subsequently designed to target the MAT1-1-1, MAT1-1-3 (of the mating type 1 idiomorph), and MAT1-2-1 (of the mating type 2 idiomorph) genes in these isolates. Results showed that all isolates contained the full gene sequence for the MAT1-2-1 gene. In addition, fragments of the MAT1-1-1 and MAT1-1-3 genes were sequenced from all isolates. These results were unexpected, as each isolate from a heterothallic species would typically contain only one of the two possible MAT idiomorphs.     

Premature differentiation and aberrant movement of pituitary cells lacking both Hes1 and Prop1

In the pituitary, the transition from proliferating progenitor cell into differentiated hormone producing cell is carefully regulated in a time-dependent and spatially-restricted manner. We report that two targets of Notch signaling, Hes1 and Prop1, are needed to maintain progenitors within Rathke's pouch and for the restriction of differentiated cells to the ventral pituitary. We observed ACTH and αGSU producing cells that had prematurely differentiated within Rathke's pouch along with correlated ectopic expression of Mash1 only when both Prop1 and Hes1 were lost. We also discovered that downregulation of N-cadherin expression in cells as they transition from Rathke's pouch to the anterior lobe appears to be essential for their movement. In the Prop1 mutant, cells are trapped in Rathke's pouch and N-cadherin expression remains high. Also, Slug, a marker of epithelial-to-mesenchymal transition, is absent in the dorsal anterior lobe. When Hes1 is lost in the Prop1 mutant, N-cadherin is downregulated and cells are able to exit Rathke's pouch but have lost their migrational cues and form ectopic foci surrounding Rathke's pouch. Our data reveal important overlapping functions of Hes1 and Prop1 in cell differentiation and movement that are critical for pituitary organogenesis.     

Chromatin breakdown by deoxyribonuclease1 promotes acetaminophen-induced liver necrosis: an ultrastructural and histochemical study on male CD-1 mice

We analyzed in male wild-type (WT) and Dnase1 knockout (KO) CD-1 mice after acetaminophen (APAP)-intoxication the hepatolobular distribution of APAP-adducts in relation to DNA-damage by terminal deoxyribonucleotidyl-transferase dUTP nick end-labeling (TUNEL), the ultrastructural alterations of hepatocellular morphology and the intracellular localization of Dnase1. Treatment of WT-mice with 600 mg/kg APAP led to extensive pericentral necrosis. Electron microscopy (EM) demonstrated vesiculation of the rough endoplasmatic reticulum and swelling of mitochondria. Pericentral WT-hepatocyte nuclei exhibited pyknosis, karyorrhexis and karyolysis. In contrast, livers from treated KO-mice exhibited almost normal light microscopical structure and EM revealed only mild signs of hepatocellular damage. In WT-mice several layers of pericentral hepatocytes displayed APAP-adduct formation and subsequent DNA-damage, whereas in KO-animals only few cells were affected. Serum aminotransferases rose similarly in both mouse strains up to 12 h, thereafter increased only in WT-mice. Immunogold-EM revealed the translocation of Dnase1 from the rER into the nuclei of treated WT-mice. In KO-mice, APAP-adduct formation was retarded and less extensive suggesting that detoxification of APAP must have been more effective in KO-mice possibly due to the lack of energy depletion otherwise caused by Dnase1-induced DNA-damage in WT-mice.