Isolation and identification of an endophytic strain of Fusarium oxysporum producing podophyllotoxin from Juniperus recurva

Podophyllotoxin, a well-known naturally occurring aryltetralin lignan occurs in few plant species that is used as a precursor for the chemical synthesis of the anticancer drugs like etoposide, teniposide and etopophose phosphate. The availiability of this lignan is becoming increasingly limited because of the scarce occurance of its natural sources and also because synthetic approaches for its production are still commercially unacceptable. This paper reports first time the production of podophyllotoxin by an endophytic fungus Fusarium oxysporum isolated from the medicinal plant Juniperus recurva. Further confirmation and quantification of podophyllotoxin was performed by HPLC, LC-MS, and LC-MS/MS.     

Sugar feeding protects against arboviral infection by enhancing gut immunity in the mosquito vector Aedes aegypti

As mosquito females require a blood meal to reproduce, they can act as vectors of numerous pathogens, such as arboviruses (e.g. Zika, dengue and chikungunya viruses), which constitute a substantial worldwide public health burden. In addition to blood meals, mosquito females can also take sugar meals to get carbohydrates for their energy reserves. It is now recognised that diet is a key regulator of health and disease outcome through interactions with the immune system. However, this has been mostly studied in humans and model organisms. So far, the impact of sugar feeding on mosquito immunity and in turn, how this could affect vector competence for arboviruses has not been explored. Here, we show that sugar feeding increases and maintains antiviral immunity in the digestive tract of the main arbovirus vector Aedes aegypti. Our data demonstrate that the gut microbiota does not mediate the sugar-induced immunity but partly inhibits it. Importantly, sugar intake prior to an arbovirus-infected blood meal further protects females against infection with arboviruses from different families. Sugar feeding blocks arbovirus initial infection and dissemination from the gut and lowers infection prevalence and intensity, thereby decreasing the transmission potential of female mosquitoes. Finally, we show that the antiviral role of sugar is mediated by sugar-induced immunity. Overall, our findings uncover a crucial role of sugar feeding in mosquito antiviral immunity which in turn decreases vector competence for arboviruses. Since Ae. aegypti almost exclusively feed on blood in some natural settings, our findings suggest that this lack of sugar intake could increase the spread of mosquito-borne arboviral diseases.     

Characterization of an enriched lipoxygenase extract from Aspergillus niger in terms of specificity and nature of flavor precursors production

Aspergillus niger was grown for 6 days, and the harvested biomass was homogenized; the resultant supernatant, considered as the crude enzymatic extract, was enriched by ammonium sulfate precipitation. The extract was assayed for its lipoxygenase (LOX) activity using a wide range of polyunsaturated fatty acids (PUFAs), including linoleic, linolenic and arachidonic acids, as substrates. Two pH maxima were determined at 5.0, 10.5. The K_m and V_max values indicated that the microbial LOX displayed preferential substrate specificity towards linolenic acid at low pH. The microbial LOX demonstrated preferential substrate specificity towards free fatty acids over the acyl esters of linoleic acid. It was shown that the LOX activity of A. niger produced all monohydroperoxy regioisomers of the PUFAs, and there was a predominance of conjugated diene hydroperoxides. Significant production of the unconjugated 10-hydroperoxides of both linoleic and linolenic acids was obtained by the LOX activity. The amounts of 10-hydroperoxides ranged from 15 to 21% of total produced isomers, for linolenic and linoleic acids, respectively. The greatest proportion of the 10-regioisomer was attributed to the maximum activity at pH 5.0. Four major hydroperoxy-eicosatetraenoic acid (HPETE) regioisomers were isolated from the bioconversion of arachidonic acid, including the 8-, 9-, 12- and 15-HPETE, which accounted for approximately 97% of total isomers.     

Promising directions in plant phenotypic plasticity

A research agenda for the next phase of plasticity studies calls for contributions from a diverse group of biologists, working both independently and collaboratively, to pursue four promising directions: examining dynamic, anatomical/architectural, and cross-generational plasticity along with simpler growth traits; carefully assessing the adaptive significance of those plasticity patterns; investigating the intricate transduction pathways that lead from environmental signal to phenotypic response; and considering the rich environmental context of natural systems. Progress in these areas will allow us to address broad and timely questions regarding the ecological and evolutionary significance of plasticity and the nature of phenotypic determination.     

Effectiveness of honey bees in delivering the biocontrol agent Bacillus subtilis to blueberry flowers to suppress mummy berry disease

Honey bees are important pollinators of commercial blueberries in the southeastern United States, and blueberry producers often use supplemental bees to achieve adequate fruit set. However, honey bees also vector the plant pathogenic fungus Monilinia vaccinii-corymbosi which infects open blueberry flowers through the gynoecial pathway causing mummy berry disease. Here, we report the results of a 3-year field study to test the hypothesis that using bee hives equipped with dispensers containing the biocontrol product Serenade, a commercial formulation of the bacterium Bacillus subtilis which has shown activity against flower infection by M. vaccinii-corymbosi in laboratory experiments, can reduce mummy berry disease incidence when honey bees are used as pollinators in blueberries. Individual honey bees carried 5.1–6.4 × 10⁵ colony-forming units (CFU) of B. subtilis when exiting hive-mounted dispensers with Serenade. On caged rabbiteye blueberry bushes in the field, population densities of B. subtilis vectored by honey bees reached a carrying capacity of <10³ CFU per flower stigma within 2 days of exposure, and there was a highly significant non-linear relationship between B. subtilis populations per stigma and bee activity, expressed as number of legitimate flower visits per time interval per cage (R = 0.6928, P < 0.0001, n = 32). Honey bee density (1600 or 6400 individuals per 5.8-m³ cage) and Serenade treatment (presence or absence of the product in hive-mounted dispensers) significantly (P < 0.05) affected the incidence of fruit mummification on caged bushes, whereby increasing bee density increased disease incidence and application of Serenade reduced disease levels. Taken together, results of this study suggest that use of a hive-dispersed biocontrol product such as Serenade as a supplement during pollination can reduce the risk of mummy berry disease. This may be a prudent practice that optimizes the benefits to pollination of high bee densities while reducing the associated disease-vectoring risk.     

Androgen receptor gene polymorphism analysis: application to screening of heterozygote and to prenatal diagnosis of androgen insensitivity syndrome]

Androgen insensitivity syndromes are X-linked disorders. Restriction fragment length polymorphism analysis of the androgen receptor gene showed that deletions were infrequent. Some mutations have been described. In these conditions, in high-risk family, carrier diagnosis is impossible unless identification of mutations is made. It is thus necessary to detect androgen receptor gene polymorphism in order to differentiate the two maternal X chromosomes. Two androgen receptor gene polymorphisms have been reported (Hind III and exon 1). In this study we analyzed these two gene polymorphisms to detect carriers in at-risk families. The combined results of the two analyses allowed us to detect carriers in 45% of the studied families. In two families the prenatal diagnosis of androgen insensitivity syndrome was performed.     

Increased peripheral aromatase activity in prepubertal children with partial androgen insensitivity syndrome

It has been suggested that rate of estrogen formation was higher in patients with androgen insensitivity syndrome (AIS). This work was designed to find out if peripheral aromatase activity could be related to a defect in androgen action in prepubertal children with male pseudohermaphroditism. Fibroblast estrogen production was assayed by a highly specific enzymatic determination. Foreskin fibroblast strains were raised from 17 children with partial androgen insensitivity (PAIS) as defined by dihydrotestosterone binding activity in cells. Results are expressed as pmol estrogens/mg proteins synthetized/day when cultured fibroblasts are incubated with D4-androstenedione. In normal prepubertal boys (n = 19), aromatase activity ranged between 5 and 10 pmol estrogens/mg proteins/day, while in postpubertal boys it varied between 15 and 34 pmol estrogens/mg proteins/day. In prepubertal boys with PAIS (n = 17) aromatase activity is highly elevated: 19.4 +/- 8.4 pmol/mg proteins/day. These results show that (a) peripheral aromatase activity is low before puberty and (b) fibroblast estrogen synthesis is significantly (p less than 0.001) increased in prepubertal children with PAIS. Our data suggest that low utilization of androgens by target cells stimulates the production of estrogen. Peripheral aromatase activity can thus be considered as a 'marker' of androgen insensitivity in prepubertal children with male pseudohermaphroditism.