Other Index

Other Index

Other Index     

Protection of olive planting stocks against parasitism of root-knot nematodes by arbuscular mycorrhizal fungi

The effects were investigated, under controlled conditions, of single and joint inoculation of olive planting stocks cvs Arbequina and Picual with the arbuscular mycorrhizal fungi (AMF) Glomus intraradices , Glomus mosseae or Glomus viscosum , and the root-knot nematodes Meloidogyne incognita and Meloidogyne javanica , on plant performance and nematode infection. Establishment of the fungal symbiosis significantly increased growth of olive plants by 88·9% within a range of 11·9–214·0%, irrespective of olive cultivar, plant age and infection by M. incognita or M. javanica . In plants free from AMF, infection by Meloidogyne spp. significantly reduced the plant main stem diameter by 22·8–38·6%, irrespective of cultivar and plant age. Establishment of AMF in olive plants significantly reduced severity of root galling by 6·3–36·8% as well as reproduction of both Meloidogyne spp. by 11·8–35·7%, indicating a protective effect against parasitism by root-knot nematodes. Infection by the nematodes influenced root colonization by AMF, but the net effect depended on the AMF isolate–olive cultivar combination. It is concluded that prior inoculation of olive plants with AMF may contribute to improving the health status and vigour of cvs Arbequina and Picual planting stocks during nursery propagation.     

Interactions of Pratylenchus thornei and Fusarium oxysporum f. sp. ciceris on Chickpea

ABSTRACT Fusarium oxysporum f. sp. ciceris and the root-lesion nematode Pratylenchus thornei coinfect chickpeas in southern Spain. The influence of root infection by P. thornei on the reaction of Fusarium wilt-susceptible (CPS 1 and PV 61) and wilt-resistant (UC 27) chickpea cultivars to F. oxysporum f. sp. ciceris race 5 was investigated under controlled and field conditions. Severity of Fusarium wilt was not modified by coinfection of chickpeas by P. thornei and F. oxysporum f. sp. ciceris, in simultaneous or sequential inoculations with the pathogens. Root infection with five nematodes per cm(3) of soil and 5,000 chlamydospores per g of soil of the fungus resulted in significantly higher numbers of propagules of F. oxysporum f. sp. ciceris with the wilt-susceptible cultivar CPS 1, but not with the wilt-resistant one. However, infection with 10 nematodes per cm(3) of soil significantly increased root infection by F. oxysporum f. sp. ciceris in both cultivars, irrespective of fungal inoculum densities (250 to 2,000 chlamydospores per g of soil). Plant growth was significantly reduced by P. thornei infection on wilt-susceptible and wilt-resistant chickpeas in controlled and field conditions, except when shorter periods of incubation (45 days after inoculation) were used under controlled conditions. Severity of root necrosis was greater in wilt-susceptible and wilt-resistant cultivars when nematodes were present in the root, irrespective of length of incubation time (45 to 90 days), densities of nematodes (5 and 10 nematodes per cm(3) of soil), fungal inocula, and experimental conditions. Nematode reproduction on the wilt-susceptible cultivars, but not on the wilt-resistant one, was significantly increased by F. oxysporum f. sp. ciceris infections under controlled and field conditions.     

Pathogenicity and histopathology of Pratylenchus thornei populations on selected chickpea genotypes

Four populations of Pratylenchus thornei from different locations were tested for reproductive fitness in axenic carrot disc cultures and for pathogenicity to chickpea cultivars JG 62 and UC 27 and lines K 850 and ILC 1929. Parasitism and histopathology on selected chickpea genotypes (JG 62, UC 27 and lines ILC 482, ICC 11324 and ICC 12237) were also investigated. Reproductive fitness, assessed as the ratio of the final number of nematodes per carrot disc to the number of nematodes inoculated, was similar among the populations tested and the four populations reproduced to a similar extent in a given chickpea genotype. However, the extent of reproduction was significantly affected by the chickpea genotype, JG 62 and UC 27 being the best and poorest hosts, respectively. Pathogenicity to chickpea genotypes was assessed by the difference in fresh root and dry shoot weights between infected and uninfected plants 90 days after inoculation. Plant growth was significantly reduced by the four nematode populations in all chickpea genotypes, with the exception of cv. JG 62, which was tolerant of P. thornei . Severity of root necrosis caused by nematode infection was similar for all populations. Histopathological studies of chickpea genotypes infected by P. thornei showed that all were suitable hosts according to nematode reproduction and host reaction. P. thornei always migrated through epidermal and cortical cells by breaking down cell walls along the nematode pathway. In the most susceptible lines (ILC 482 and JG 62), damage to endodermal cells adjacent to nematode feeding sites was occasionally observed.     

Impacts of Burrowing Ghost Shrimp, Genus Lepidophthalmus Crustacea: Decapoda: Thalassinidea, on Penaeid Shrimp Culture

Abstract The burrowing ghost shrimp Lepidophthalmus sinuensis Lemaitre and Rodrigues and Lepidophthalmus bocourd (A. Milne Edwards) have significant impacts on pond-based culture of penaeid shrimp. Marked abbreviation of the larval cycle, an adaptation for estuarine retention in wild populations, favors accumulation of recruits into the same substrates as the parental population where densities of these burrowers sometimes exceed 650 individuals/m². Higher densities of burrowing shrimp appear to correlate with lower yields of penaeid shrimp because of oxygen requirements by the thalassinids and also bioturbation effects. Rich sources of organic materials in highly reduced pond substrates can be readily exploited by Lepidophthalmus species due to their physiological adaptations to low oxygen concentrations. Bioturbation and ventilatory movement of water through burrowed sediments by ghost shrimp move reduced nutrients into the water column with potential toxic effects on penaeids. Ultimately, activities of these estuarine burrowers oxidize benthic sediments and cycle nutrients into the water column, the negative impacts of which are probably restricted to aquaculture settings.     

Isolation of bovine ovarian inhibin, its immunoneutralization in vitro and immunolocalization in bovine ovary

A purification scheme involving gel permeation chromatography, anion exchange chromatography and reversed-phase high performance liquid chromatography (RP-HPLC) was used to isolate from bovine follicular fluid (FF) biologically-active inhibin of molecular weight 32 kDa. Chromatographic fractions were monitored for inhibin-like biological activity (ILA) using a simplified bioassay procedure in which a suppression of total basal FSH production by rat pituitary cells in monolayer culture indicates the presence of ILA. Approximately 3 mg protein having an ILA potency (ED50 value in in vitro bioassay) of 1.7 ng/ml was obtained from 4 1 crude bovine FF (260 g protein; ILA potency 3750 ng/ml) reflecting an approximate 2200-fold purification factor with an overall recovery of about 3%. The isolated material appeared as a single major UV absorbance peak on RP-HPLC and as a single band (32 kDa) when subjected to SDS-PAGE (15% gel) under non-reducing conditions. Under reducing conditions the molecule dissociated into 2 subunits of apparent molecular weight 22 and 14 kDa confirming that it is probably identical to the 31/32 kDa form of bovine ovarian inhibin previously reported by two other independent research groups. An antiserum raised in a chicken against the isolated material completely neutralized the suppressive effects of both 32 kDa inhibin and bovine FF on basal production of FSH by rat pituitary cells in vitro but only partially reversed the suppressive effects of both porcine and human FF. Immunohistochemical staining of sections of bovine ovary and of isolated preparations of bovine granulosa cells using this antiserum confirmed that granulosa cells are a major source of inhibin. The observation that specific immunostaining was not confined to these cells, however, suggests that they may not be the exclusive source of immunoreactive inhibin in the bovine ovary.     

Changes in hydrophilic and lipophilic antioxidant activity and related bioactive compounds during postharvest storage of yellow and purple plum cultivars

Eight plum cultivars (four dark-purple and four yellow) were harvested at the commercial ripening stage, and changes of fruit quality properties were evaluated during cold storage and subsequent shelf-life, with special emphasis on bioactive compounds (phenolics, anthocyanins and carotenoids) and antioxidant activity (TAA). From the eight plum cultivars, four showed the typical climacteric ripening pattern (‘Blackamber’, ‘Larry Ann’, ‘Golden Globe’ and ‘Songold’) while four behaved as suppressed-climacteric types (‘Golden Japan’ ‘Angeleno’, Black Diamond’ and ‘TC Sun’), the latter being described for the first time. At harvest, large variations in phytochemicals and antioxidant activity were found among cultivars in peel and pulp tissues, although phytochemical concentration and antioxidant activity were higher in the peel than in the flesh (2–40-fold depending on the bioactive compound). During storage, increases in total phenolics for all cultivars (peel and pulp), in total anthocyanin content in the peel of the dark-purple plums, and total carotenoids in the peel and pulp of the yellow cultivars were observed. This behaviour of the bioactive compounds was reflected in TAA changes, since hydrophilic-TAA (H-TAA) was correlated with both phenolics and anthocyanins, while lipophilic-TAA (L-TAA) was correlated with carotenoids. L-TAA comprised about 30–50% of the TAA in plum tissues. Carotenoids and phenolics (and among them the anthocyanins) could be the main lipophilic and hydrophilic compounds contributing to L-TAA and H-TAA, respectively. No significant loss of bioactive compounds and TAA occurred during prolonged plum storage. Moreover, for a better evaluation of the antioxidant potential of plums, the contribution to carotenoids should not be overlooked.     

Pimarane diterpene from Viguiera arenaria (Asteraceae) inhibit rat carotid contraction

ent-Pimara-8(14),15-dien-19-oic acid (PA) isolated from Viguiera arenaria (Asteraceae; Heliantheae) inhibited rat carotid rings contraction induced by phenylephrine (10(-8) mol/l) or potassium chloride (45 mmol/l) at concentration ranging from 5 to 20 microg/ml. This inhibitory effect was not reversible after the removal of this compound from the medium bath.     

Inhibitory action of kaurenoic acid from Viguiera robusta (Asteraceae) on phenylephrine-induced rat carotid contraction

ent-kaurenoic acid (KA) isolated from Viguiera robusta was tested for activity on vascular smooth muscle contactility. Cumulative concentration-response curves were obtained for a stepwise increase (10(-10)-10(-05) mol/l) in the concentration of phenylephrine (Phe), a selective alpha(1)-adrenergic agonist. The effects in the presence of KA (0.2, 2.0 and 20.0 microg/ml), and 90 min after the removal of KA from the medium bath were compared to controls. At 20.0 microg/ml, KA inhibited the in vitro contractility of rat carotid artery elicited by Phe, but had no effect at lower concentrations (0.2 and 2.0 microg/ml). The effect elicited by KA was reversible after 90 minutes.