Evaluation of citrus somatic hybrids for tolerance to Phytophthora nicotianae and citrus tristeza virus

Somatic hybridization is a biotechnology tool that can be used in citrus breeding programs to produce somatic hybrids with the complete genetic combination of both parents. The goal of this work was to test the reaction of citrus somatic hybrids that may be useful as rootstocks to trunk and root infections caused by Phytophthora nicotianae van Breda de Haan (P. parasitica Dastur) and to citrus tristeza virus (CTV). The somatic hybrids evaluated were ‘Caipira’ sweet orange (Citrus sinensis L. Osbeck) + ‘Rangpur’ lime (C. limonia Osbeck), ‘Caipira’ sweet orange + ‘Cleopatra’ mandarin (C. reshni hort. ex Tanaka), ‘Caipira’ sweet orange + ‘Volkamer’ lemon (C. volkameriana V. Ten. & Pasq.), ‘Caipira’ sweet orange + rough lemon (C. jambhiri Lush.), ‘Cleopatra’ mandarin + ‘Volkamer’ lemon, ‘Cleopatra’ mandarin + sour orange (C. aurantium L.), ‘Rangpur’ lime + ‘Sunki’ mandarin (C. sunki (Hayata) hort. ex Tanaka), ‘Ruby Blood’ sweet orange (C. sinensis L. Osbeck) + ‘Volkamer’ lemon, ‘Rohde Red’ sweet orange (C. sinensis L. Osbeck) + ‘Volkamer’ lemon, and ‘Valencia’ sweet orange + Fortunella obovata hort. ex Tanaka. For P. nicotianae trunk and root infection assays, plants of the somatic hybrids, obtained from 9-month semi-hardwood cuttings, were evaluated and compared with diploid citrus rootstock cultivars after mycelia inoculation in the trunk or spore infestation in the substrate, respectively. ‘Cleopatra’ mandarin + sour orange, ‘Rangpur’ lime + ‘Sunki’ mandarin, ‘Cleopatra’ mandarin + ‘Volkamer’ lemon, ‘Ruby Blood’ sweet orange + ‘Volkamer’ lemon, ‘Rohde Red’ sweet orange + ‘Volkamer’ lemon, and ‘Caipira’ sweet orange + ‘Volkamer’ lemon had less trunk rot occurrence, whereas the somatic hybrids ‘Cleopatra’ mandarin + ‘Volkamer’ lemon, ‘Cleopatra’ mandarin + sour orange, ‘Caipira’ sweet orange + ‘Volkamer’ lemon, and ‘Caipira’ sweet orange + ‘Rangpur’ lime were tolerant to root rot. For CTV assays, plants of the somatic hybrids along with tolerant and intolerant rootstocks were budded with a mild strain CTV-infected or healthy ‘Valencia’ sweet orange budwood. Differences in average scion shoot length indicated that the hybrids ‘Cleopatra’ mandarin + sour orange and ‘Valencia’ sweet orange + Fortunella obovata were intolerant to CTV.     

Driving factors determining the occurrence of sodic soils in dry subhumid Mediterranean areas

An evaluation of the factors determining the occurrence and the properties of soils with low permeability occurring in vast areas in S Portugal was carried out taking into account the terrain morphology and the geology of the region. This paper deals with the variation patterns of the physical and chemical characteristics of soils from several soil toposequences that occur under different gradient slopes and on different parent rocks. Spatial variation of soil properties mainly depends on the composition of their cation‐exchange complex, as the role of other factors, such as the mineralogy of the clay fraction, were of minor importance. There is often a stronger increment of Na and/or Mg than of Ca with depth, causing a variable degree of sodicity in some of these soils, to which waterlogging tendency of their upper horizons is related. Though the occurrence of these features is determined by the nature of the parent rock, their degree of expression varies primarily according to the topographic position of soils. Therefore, a catenary distribution including nonsodic Cambisols or Luvisols in the hillcrests and Stagnic Solonetz or Sodic Luvisols or Sodic Stagnosols in the topographic lows is common. Such soil characteristics are of utmost importance for irrigation suitability and management of these soils, and for environmental impacts assessment, as the region is vulnerable to desertification.     

Antifungal activity evaluation of the constituents of Haliclona baeri and Haliclona cymaeformis, collected from the Gulf of Thailand

A new compound maleimide-5-oxime was isolated, together with 3,4-dihydroxybenzoic acid, tetillapyrone, from the ethyl acetate extract of the marine sponge Haliclona baeri while tetillapyrone, nortetillapyrone, p-hydroxybenzaldehyde and phenylacetic acid were isolated from the ethyl acetate extract of Haliclona cymaeformis, collected from the Gulf of Thailand. The structures of tetillapyrone and nortetillapyrone were re-examined using HMBC correlations. Maleimide-5-oxime, tetillapyrone and nortetillapyrone were found to be inactive against three human tumor cell lines (the estrogen-dependent ER(+) MCF-7, the estrogen-independent ER(−) MDA-MB-231 and NCI-H460. Maleimide-5-oxime, p-hydroxybenzaldehyde, phenylacetic acid, tetillapyrone and nortetillapyrone were evaluated for their growth inhibitory effect against seven yeasts and eight filamentous fungi. Only nortetillapyrone showed antifungal activity, with a preponderance on the dermatophytic filamentous fungi.     

The value of sexed bovine semen

Semen sexing may be used in a variety of practical situations, where part (or all) of the herd may be inseminated with X‐ and Y‐chromosome‐enriched semen. Expressions are presented to calculate the net present value of progeny derived from a semen dose, dependent on the values of females and males, and on the efficiency of sexing. Sexed semen allows selling a higher proportion of the more valuable sex and also increases the value of animals retained for breeding through more intense selection. The expressions to economically evaluate sexed semen are quite general but numerical examples are presented for several practical situations of interest in Brazil.     

Evaluation of ‘Hamlin’ sweet orange + ‘Montenegrina’ mandarin somatic hybrid for tolerance to Xanthomonas axonopodis pv. citri and Xylella fastidiosa

Asiatic citrus canker (ACC), caused by Xanthomonas axonopodis Starr & Garces pv. citri (Hasse) Vauterin et al., and citrus variegated chlorosis (CVC), caused by Xylella fastidiosa Wells et al., are considered the main diseases affecting sweet orange scion varieties in Brazil. Among commercial varieties, mandarins and tangerines are recognized as tolerant to these pathogens. We report herein the production of ‘Hamlin’ sweet orange (Citrus sinensis L. Osbeck) + ‘Montenegrina’ mandarin (Citrus deliciosa Ten.) allotetraploid somatic hybrid plants by protoplast fusion with improved disease tolerance that could be used as a donor of resistance genes in interploid hybridisation. Somatic hybridisation was confirmed by leaf morphology, flow cytometry and RAPD analyses. The somatic hybrid was propagated by grafting and cultivated in a screenhouse for tolerance assays. For X. axonopodis pv. citri assays, buds were collected from both ‘Hamlin’ sweet orange and the somatic hybrid and grafted onto ‘Cleopatra’ mandarin (Citrus reshni hort. ex Tanaka). As a negative control, buds from ‘Mexerica Tardia’ mandarin (C. deliciosa) were collected and grafted onto ‘Cleopatra’ mandarin. Two-month old plants with at least one young vegetative flush were individually spray-inoculated with a 10⁶ CFU mL⁻¹X. axonopodis pv. citri suspension and incubated in a growth chamber, at 27 °C, under 16-h photoperiod. The somatic hybrid showed a statistically significant reduction in susceptibility to ACC 30 days after inoculation. Compared to ‘Hamlin’ sweet orange, disease severity was reduced by 70%, with similar tolerance to that of the mandarin negative control. For X. fastidiosa assays, buds were collected from the somatic hybrid and its parental plants and grafted onto ‘Rangpur’ lime (Citrus limonia Osbeck). The developed plants were needle-inoculated with a X. fastidiosa suspension (8.7 × 10¹⁰ CFU mL⁻¹) into the new growth flush stem. Bacterial population was quantified both at 4 (at the inoculation point) and 8 months (50 cm above the inoculation point) after inoculation. The first evaluation detected X. fastidiosa in 63% of ‘Hamlin’ sweet orange and ‘Hamlin’ + ‘Montenegrina’ mandarin samples. In the second evaluation, X. fastidiosa was detected in 47.4% of ‘Hamlin’ sweet orange and 10.5% of ‘Hamlin’ + ‘Montenegrina’ somatic hybrid samples, suggesting that bacterial movement was restricted in the somatic hybrid. X. fastidiosa was not detected in both evaluations in samples collected from leaves of ‘Montenegrina’ mandarin. These results indicate that the ‘Hamlin’ sweet orange + ‘Montenegrina’ mandarin somatic hybrid has potential for improved disease tolerance that should enhance its value regarding future use in citrus breeding programs.     

Metabolites from Marine-Derived Fungi as Potential Antimicrobial Adjuvants

Marine-derived fungi constitute an interesting source of bioactive compounds, several of which exhibit antibacterial activity. These acquire special importance, considering that antimicrobial resistance is becoming more widespread. The overexpression of efflux pumps, capable of expelling antimicrobials out of bacterial cells, is one of the most worrisome mechanisms. There has been an ongoing effort to find not only new antimicrobials, but also compounds that can block resistance mechanisms which can be used in combination with approved antimicrobial drugs. In this work, a library of nineteen marine natural products, isolated from marine-derived fungi of the genera Neosartorya and Aspergillus, was evaluated for their potential as bacterial efflux pump inhibitors as well as the antimicrobial-related mechanisms, such as inhibition of biofilm formation and quorum-sensing. Docking studies were performed to predict their efflux pump action. These compounds were also tested for their cytotoxicity in mouse fibroblast cell line NIH/3T3. The results obtained suggest that the marine-derived fungal metabolites are a promising source of compounds with potential to revert antimicrobial resistance and serve as an inspiration for the synthesis of new antimicrobial drugs.     

Sulfated polysaccharides in marine sponges: extraction methods and anti-HIV activity

The extraction, fractionation and HIV-1 inhibition potential of polysaccharides extracted from three species of marine sponges, Erylus discophorus, Cliona celata and Stelletta sp., collected in the Northeastern Atlantic, is presented in this work. The anti-HIV activity of 23 polysaccharide pellets and three crude extracts was tested. Crude extracts prepared from Erylus discophorus specimens were all highly active against HIV-1 (90 to 95% inhibition). Cliona celata pellets showed low polysaccharide content (bellow 38.5%) and almost no anti-HIV activity (<10% inhibition). Stelletta sp. pellets, although quite rich in polysaccharide (up to 97.3%), showed only modest bioactivity (<36% HIV-1 inhibition). Erylus discophorus pellets were among the richest in terms of polysaccharide content (up to 98%) and the most active against HIV-1 (up to 95% inhibition). Chromatographic fractionation of the polysaccharide pellet obtained from a specimen of Erylus discophorus (B161) yielded only modestly active fractions. However, we could infer that the active molecule is most probably a high molecular weight sulfated polysaccharide (>2000 kDa), whose mechanism is possibly preventing viral attachment and entry (fusion inhibitor).     

Administration of meloxicam to improve the welfare of mice in research: a systematic review (2000 – 2020)

Veterinary Research Communications - Although laboratory animals experience pain as a necessary component of the objectives of experimental protocols, the level of pain should be minimized through...     

Paratuberculosis in European wild rabbits from the Iberian Peninsula

Of the non-ruminant wildlife species known to harbor Mycobacterium avium paratuberculosis (MAP), the rabbit (Oryctolagus cuniculus) is thought to pose the greatest risk of transmission to cattle. We analyzed 80 hunter-harvested wild rabbits from a core study area in southern Spain, and sera from 157 wild rabbits sampled opportunistically on seven additional sites. Gross lesions compatible with paratuberculosis were observed in two of 80 necropsied rabbits. Histopathology revealed focal to diffuse multibacillary MAP-compatible lesions in 8 of 10 rabbits examined. Presence of MAP was confirmed in one rabbit with gross lesions by positive amplification curves for both IS900 and ISMAP02. However, no isolate was obtained from 47 samples by culture. We adapted an indirect ELISA for the detection of MAP antibodies. At the established cut-off of 0.5, 6 of 237 wild rabbit sera (2.5%) yielded a positive ELISA result. Antibodies were detected in rabbits from 3 of 8 sampling sites. Considering the increasing relevance of MAP infection for animal health, these results open a challenging field for future research.