Induced parthenogenesis in mandarin for haploid production: induction procedures and genetic analysis of plantlets

This study focused on haploid induction in mandarin through in situ gynogenesis by pollination with irradiated pollen of ‘Meyer’ lemon. Pollination was carried out for three genotypes of mandarin with four levels of gamma-ray-irradiated pollen (150, 300, 600, and 900 Gy). The resulting seeds were characterised by a small size. Embryos were rescued in vitro and the ploidy level of the plantlets was determined by flow cytometry analysis. Haploid, diploid, triploid plantlets were obtained. The haploid parthenogenetic origin was confirmed using microsatellite marker analysis and chromosome count. Diploid and triploid plants were the result of crosses between mandarin and lemon. The induction of gynogenetic haploids of ‘Fortune’ (Citrus clementina Hort ex Tan. × Citrus tangerina Hort ex Tan.) and ‘Ellendale’ (Citrus reticulata Blanco × Citrus sinensis L. Osb) is reported here for the first time.     

Corynebacterium diphtheriae putative tellurite-resistance protein (CDCE8392_0813) contributes to the intracellular survival in human epithelial cells and lethality of Caenorhabditis elegans

Corynebacterium diphtheriae, the aetiologic agent of diphtheria, also represents a global medical challenge because of the existence of invasive strains as causative agents of systemic infections. Although tellurite (TeO3^2-) is toxic to most microorganisms, TeO3^2--resistant bacteria, including C. diphtheriae, exist in nature. The presence of TeO3^2--resistance (Te^R) determinants in pathogenic bacteria might provide selective advantages in the natural environment. In the present study, we investigated the role of the putative Te^R determinant (CDCE8392_813gene) in the virulence attributes of diphtheria bacilli. The disruption of CDCE8392_0813 gene expression in the LDCIC-L1 mutant increased susceptibility to TeO3^2- and reactive oxygen species (hydrogen peroxide), but not to other antimicrobial agents. The LDCIC-L1 mutant also showed a decrease in both the lethality of Caenorhabditis elegans and the survival inside of human epithelial cells compared to wild-type strain. Conversely, the haemagglutinating activity and adherence to and formation of biofilms on different abiotic surfaces were not regulated through the CDCE8392_0813 gene. In conclusion, the CDCE8392_813 gene contributes to the Te^R and pathogenic potential of C. diphtheriae.     

Involvement of Arabidopsis Hexokinase1 in Cell Death Mediated by Myo-Inositol Accumulation

Programmed cell death (PCD) is essential for several aspects of plant life, including development and stress responses. We recently identified the mips1 mutant of Arabidopsis thaliana, which is deficient for the enzyme catalyzing the limiting step of myo-inositol (MI) synthesis. One of the most striking features of mips1 is the light-dependent formation of lesions on leaves due to salicylic acid (SA)-dependent PCD. Here, we identified a suppressor of PCD by screening for mutations that abolish the mips1 cell death phenotype. Our screen identified the hxk1 mutant, mutated in the gene encoding the hexokinase1 (HXK1) enzyme that catalyzes sugar phosphorylation and acts as a genuine glucose sensor. We show that HXK1 is required for lesion formation in mips1 due to alterations in MI content, via SA-dependant signaling. Using two catalytically inactive HXK1 mutants, we also show that hexokinase catalytic activity is necessary for the establishment of lesions in mips1. Gas chromatography-mass spectrometry analyses revealed a restoration of the MI content in mips1 hxk1 that it is due to the activity of the MIPS2 isoform, while MIPS3 is not involved. Our work defines a pathway of HXK1-mediated cell death in plants and demonstrates that two MIPS enzymes act cooperatively under a particular metabolic status, highlighting a novel checkpoint of MI homeostasis in plants.     

Detecting non-allelic homologous recombination from high-throughput sequencing data

Non-allelic homologous recombination (NAHR) is a common mechanism for generating genome rearrangements and is implicated in numerous genetic disorders, but its detection in high-throughput sequencing data poses a serious challenge. We present a probabilistic model of NAHR and demonstrate its ability to find NAHR in low-coverage sequencing data from 44 individuals. We identify NAHR-mediated deletions or duplications in 109 of 324 potential NAHR loci in at least one of the individuals. These calls segregate by ancestry, are more common in closely spaced repeats, often result in duplicated genes or pseudogenes, and affect highly studied genes such as GBA and CYP2E1.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-015-0633-1) contains supplementary material, which is available to authorized users.     

Immunolocalization of IFN-gamma in the lesions of resistant and susceptible mice to Paracoccidioides brasiliensis infection

The important role of interferon-gamma (IFN-γ) in protective immunity in mycosis is well established, except for its participation in fungal granulomas. Herein, we employ immunohistochemical reactions to describe the in situ localization of IFN-γ in granulomas of susceptible (B10.A) and resistant (A/J) mice to infection with Paracoccidioides brasiliensis (Pb). After infection with the highly virulent Pb18, IFN-γ-positive lymphomononuclear cells were localized mainly at the periphery of granulomas in both mouse strains. The numbers of positive cells found in compact granulomas of A/J mice increased significantly from 15 to 120 days postinfection. At this time, significantly more positive cells were detected in the compact granulomas of resistant mice than in the loose, multifocal lesions of the susceptible ones. In infection with the slightly virulent Pb265, the same pattern of IFN-γ localization was found as in Pb18 infection, but there was decreased staining at 120 days due to the presence of only residual lesions in both mouse strains. The marked IFN-γ staining observed in the granulomas of resistant mice at the later stage of Pb infection confirms its importance in fungal dissemination control, and suggests a contribution to the development of paracoccidioidal granuloma.     

Chemical and microbiological changes during vermicomposting of coffee pulp using exotic (<Emphasis Type="Italic">Eudrilus eugeniae</Emphasis>) and native earthworm (<Emphasis Type="Italic">Perionyx ceylanesis</Emphasis>) species

Coffee pulp is the main solid residue from the wet processing of coffee berries. Due to presence of anti-physiological and anti-nutritional factors, coffee pulp is not considered as adequate substrate for bioconversion process by coffee farmers. Recent stringent measures by Pollution Control authorities, made it mandatory to treat all the solid and liquid waste emanating from the coffee farms. A study was conducted to evaluate the efficiency of an exotic (Eudrilus eugeniae) and a native earthworm (Perionyx ceylanesis) from coffee farm for decomposition of coffee pulp into valuable vermicompost. Exotic earthworms were found to degrade the coffee pulp faster (112 days) as compared to the native worms (165 days) and the vermicomposting efficiency (77.9%) and vermicompost yield (389 kg) were found to significantly higher with native worms. The multiplication rate of earthworms (280%) and worm yield (3.78 kg) recorded significantly higher with the exotic earthworms. The percentage of nitrogen, phosphorous, potassium, calcium and magnesium in vermicompost was found to increase while C:N ratio, pH and total organic carbon declined as a function of the vermicomposting. The plant nutrients, nitrogen (80.6%), phosphorus (292%) and potassium (550%) content found to increase significantly in the vermicompost produced using native earthworms as compared to the initial values, while the calcium (85.7%) and magnesium (210%) content found to increase significantly in compost produced utilizing exotic worms. Vermicompost and vermicasts from native earthworms recorded significantly higher functional microbial group’s population as compared to the exotic worms. The study reveals that coffee pulp can be very well used as substrate for vermicomposting using exotic (Eudrilus eugeniae) and native earthworm (Perionyx ceylanesis).