Floral analysis as a tool to diagnose iron chlorosis in orange trees

A three-year field experiment was conducted in a commercial orange grove [Citrus sinensis (L.) Osb. cv. `Valencia late' grafted on Citrange Troyer] established on a calcareous soil in the south of Portugal, to investigate if flower analysis could be used to diagnose lime-induced iron chlorosis. In April, during full bloom, flowers and leaves were collected from 20 trees. Leaf samples were again collected from the same trees in May, June, July and August. Total chlorophyll was estimated in all the leaves sampled for foliar analysis, using a SPAD-502 apparatus. Leaves and flowers were analysed for N, P, K, Ca, Mg, Fe, Zn, Mn and Cu. Principal Component Analysis was used to evaluate the variation of nutrient concentrations in flowers, and linear regressions were established between these and the chlorophyll content of leaves 90 days after full bloom. Evaluation of the best-fit equation was carried out using separate data obtained from other groves. Variation in the pattern of floral mineral composition in the flowers showed contrasts between the increase in N, P and K and that of Ca, Fe and Zn, while the concentration of Mg, Mn and Ca varied synchronously. The ratio of Mg:Zn in flowers explained about half of the variation of chlorophyll in leaves later in the season. A ratio below 100 indicated that trees would develop iron chlorosis, while with a ratio above 200 leaves would remain green. An early prognosis of iron chlorosis based on floral analysis can benefit growers, since it allows them to apply treatments in time to prevent loss of fruit yield and quality due to iron chlorosis.     

Streptomyces lunalinharesii spores contain chitin on the outer sheath

Chitin from Streptomyces lunalinharesii spores, detected on its outermost surface layer, was isolated and characterized by chemical and spectroscopic methods, transmission electron microscopy and flow cytometry analysis. Gold–chitinase- and gold–lectin ( Lycopersicum esculentum agglutinin, LEA)-conjugated labels were used in microscopy experiments, whereas a fluorescence–lectin (LEA) conjugate was used in flow cytometry analysis. Chitin isolation consisted of several steps of hot alkali and nitrous acid treatment, and the final material was obtained in the colloidal form. The infrared and the ¹³C CP/MAS NMR spectra of Streptomyces sp. colloidal chitin and colloidal chitin obtained from commercial crab shell chitin were very similar. Incubation of the spores with gold-labeled lectin, or gold-labeled recombinant chitinase, showed the presence of gold particles around the spore surface, indicating the specific binding of the lectin or the recombinant chitinase with the chitin present on the outermost surface. Flow cytometry analysis, using the fluorescence–lectin conjugate, confirmed these results. According to scanning electron microscopy, S. lunalinharesii presented spore surface ornamentation belonging to the spiny group. This is the first detailed characterization of chitin on the spore's outermost layer from a Streptomyces species.     

Testicular Volume and Reproductive Status of Wild <Emphasis Type="Italic">Callithrix jacchus</Emphasis>

The social relationship dynamic among callitrichid females is well known. Breeding exclusivity by dominant females involves female-female competition, usually resulting in the inhibition of subordinate reproduction. However, the strategies to maintain the male breeding position are still unclear. Researchers have observed no overt aggression between males, and differences in testosterone levels between dominant and subordinate individuals do not correlate with differences in reproductive success. In Callithrix monogamy is the predominant mating system, and testicular size is compatible with the absence of sperm competition. We analyzed testicular volume during development in 95 individuals at different ages (infant n = 12, juvenile n = 9, subadult n = 15, and adult n = 59). We also investigated if the ratio between testicular volume and body mass correlates with breeding position in the social group. The ratio was significantly higher in breeding males and a positive correlation between body mass and testicular volume is significant only for nonbreeding males. The findings suggest that testicular size varies with male reproductive status in the social group and that the enlargement of testicular volume in breeding common marmoset males seems to be a result of proximate causes and to depend on social and reproductive contexts acting together or separately.     

Recovering polyploid papaya in vitro regenerants as screened by flow cytometry

Several protocols have been proposed for in vitro propagation of papaya, either based on somatic embryogenesis or shoot organogenesis. It is well-known that tissue culture-based approaches are frequently associated with somaclonal variation. Whether on the one hand this phenomenon can preclude further stages of in vitro culture, on the other hand it can generate useful genetic variability for crop improvement. However, somaclonal variation analyses are limited in papaya tissue culture. The DNA ploidy level of 250 papaya somatic embryogenesis-derived plantlets from immature zygotic embryos was analyzed by flow cytometry. In vitro-grown and greenhouse seed-derived plantlets were used as diploid standards. Flow cytometry unambiguously evidenced euploid (diploid, mixoploid, triploid and tetraploid) and aneuploid papaya plantlets, indicating that in vitro culture conditions can lead the occurrence of somaclonal variation. Additionally, the two subsequent flow cytometry analyses showed that the DNA ploidy level remained stable in all cloned papaya plantlets during the successive subcultures in the multiplication medium.     

Quaternary climate changes explain diversity among reptiles and amphibians

It is widely believed that contemporary climate determines large-scale patterns of species richness. An alternative view proposes that species richness reflects biotic responses to historic climate changes. These competing "contemporary climate" vs "historic climate" hypotheses have been vigorously debated without reaching consensus. Here, we test the proposition that European species richness of reptiles and amphibians is driven by climate changes in the Quaternary. We find that climate stability between the Last Glacial Maximum (LGM) and the present day is a better predictor of species richness than contemporary climate; and that the 0°C isotherm of the LGM delimits the distributions of narrow-ranging species, whereas the current 0°C isotherm limits the distributions of wide-ranging species. Our analyses contradict previous studies of large-scale species richness patterns and support the view that "historic climate" can contribute to current species richness independently of and at least as much as contemporary climate.     

In?vitro evaluation of the effect of the nematophagous fungi Duddingtonia flagrans , Monacrosporium sinense and Pochonia chlamydosporia on Schistosoma mansoni eggs

The in vitro effect of four isolates of the nematophagous fungi Duddingtonia flagrans (AC 001), Monacrosporium sinense (SF 53) and Pochonia chlamydosporia (VC 1 and VC 4) on eggs of Schistosoma mansoni was examined. One thousand S. mansoni eggs were plated on 2% water–agar with the grown isolates and control without fungus. After 7, 14 and 21 days, the eggs were removed and classified according to the following parameters: type 1, lytic effect without morphological damage to eggshell; type 2, lytic effect with morphological alteration of embryo and eggshell; and type 3, lytic effect with morphological alteration of embryo and eggshell, besides hyphal penetration and internal egg colonization. Significant differences (P < 0.01) were found among the studied fungal isolates for ovicidal activity, confirming type 3 effect for the isolates VC 1 and VC 4, which characterizes the ovicidal activity of a fungus. Type 3 effect was only found for P. chlamydosporia (VC 1 and VC 4) with 26.6 and 17.2%, 25.6 and 22.6%, 27.4 and 23.9% in the 7, 14 and 21 days respectively (P < 0.01). P. chlamydosporia can thus be a potential biological control agent for S. mansoni eggs.     

Increase in Reactive Oxygen Species and Activation of Akt Signaling Pathway in Neuropathic Pain

Neuropathic pain occurs as a result of peripheral or central nervous system injury. Its pathophysiology involves mainly a central sensitization mechanism that may be correlated to many molecules acting in regions involved in pain processing, such as the spinal cord. It has been demonstrated that reactive oxygen species (ROS) and signaling molecules, such as the serine/threonine protein kinase Akt, are involved in neuropathic pain mechanisms. Thus, the aim of this study was to provide evidence of this relationship. Sciatic nerve transection (SNT) was used to induce neuropathic pain in rats. Western blot analysis of Akt and 4-hydroxy-2-nonenal (HNE)-Michael adducts, and measurement of hydrogen peroxide (H₂O₂) in the lumbosacral spinal cord were performed. The main findings were found seven days after SNT, when there was an increase in HNE-Michael adducts formation, total and p-Akt expression, and H₂O₂ concentration. However, one and 15 days after SNT, H₂O₂ concentration was raised in both sham (animals that were submitted to surgery without nerve injury) and SNT groups, showing the high sensibility of this ROS to nociceptive afferent stimuli, not only to neuropathic pain. p-Akt also increased in sham and SNT groups one day post injury, but at 3 and 7 days the increase occurred exclusively in SNT animals. Thus, there is crosstalk between intracellular signaling pathways and ROS, and these molecules can act as protective agents in acute pain situations or play a role in the development of chronic pain states.     

Serine protease activities in Oxysarcodexia thornax (Walker) (Diptera: Sarcophagidae) first instar larva

We report for the first time the expression of multiple protease activities in the first instar larva (L1) of the flesh fly Oxysarcodexia thornax (Walker). Zymographic analysis of homogenates from freshly obtained L1 revealed a complex proteolytic profile ranging from 21.5 to 136 kDa. Although some activities were detected at pH 3.5 and 5.5, the optimum pH for most of the proteolytic activities was between pH 7.5 and 9.5. Seven of 10 proteases were completely inactivated by phenyl-methyl sulfonyl-fluoride, suggesting that main proteases expressed by L1 belong to serine proteases class. Complete inactivation of all enzymatic activities was obtained using N-p-Tosyl-L-phenylalanine chloromethyl ketone (100 microM), a specific inhibitor of chymotrypsin-like serine proteases.     

Molecular paleoparasitological diagnosis of Ascaris sp. from coprolites: new scenery of ascariasis in pre-Colombian South America times

Paleoparasitological studies using microscopy showed that Ascarisand Trichuris trichiura are the human intestinal parasites most found in archaeological sites. However, in pre-Columbian South American archaeological sites, Ascaris is rare. In this work we standardized a molecular methodology for Ascaris diagnosis directly from ancient DNA retrieved from coprolites. Using cythochrome b gene (142 bp) target, ancient DNA sequences were retrieved from South American samples, negative by microscopy. Moreover, the methodology applied was sensitive enough to detect ancient DNA extracted from 30 Ascaris eggs from an European coprolite. These results revealed a new scenery for the paleodistribution of Ascaris in South America.