Expression of the maize proteinase inhibitor (mpi) gene in rice plants enhances resistance against the striped stem borer (Chilo suppressalis): effects on larval growth and insect gut proteinases

The maize proteinase inhibitor (mpi) gene was introduced into two elite japonica rice varieties. Both constitutive expression of the mpi gene driven by the maize ubiquitin 1 promoter and wound-inducible expression of the mpi gene driven by its own promoter resulted in the accumulation of MPI protein in the transgenic plants. No effect on plant phenotype was observed in mpi-expressing lines. The stability of transgene expression through successive generations of mpi rice lines (up to the T(4) generation) and the production of functional MPI protein were confirmed. Expression of the mpi gene in rice enhanced resistance to the striped stem borer (Chilo suppressalis), one of the most important pests of rice. In addition, transgenic mpi plants were evaluated in terms of their effects on the growth of C. suppressalis larvae and the insect digestive proteolytic system. An important dose-dependent reduction of larval weight of C. suppressalis larvae fed on mpi rice, compared with larvae fed on untransformed rice plants, was observed. Analysis of the digestive proteolytic activity from the gut of C. suppressalis demonstrated that larvae adapted to mpi transgene expression by increasing the complement of digestive proteolytic activity: the serine and cysteine endoproteinases as well as the exopeptidases leucine aminopeptidase and carboxypeptidases A and B. However, the induction of such proteolytic activity did not prevent the deleterious effects of MPI on larval growth. The introduction of the mpi gene into rice plants can thus be considered as a promising strategy to protect rice plants against striped stem borer.     

Superficial infections caused by Microsporum canis in humans and animals

Dermatophytic infections caused by M. canis in humans and animals have a world wide distribution and they are zoonotic. The objective in this work was to know the frequency of M. canis infections in humans and pets. We studied our cases from January 1994 to December 2002. The human samples were obtained from a Dermatological Department in a General Hospital and we registered the next data: age, sex, job, and affected area. The animal samples were obtained from a mycological veterinary laboratory, and we registered the presence or absence of clinical lesions. A total of 46 clinical cases of M. canis infections were recorded, 26 female and 20 males: tinea capitis 21, tinea corporis 17, tinea pedis five, onychomycosis two, and only one case with tinea faciei. The 46 cases with positive culture yield 42 positive samples in KOH. The age range varied from 2 to 60 years. Among the animals, we studied 461 dogs and found six KOH positive (1%) samples and cultured 23 isolates (4.98%): 21 M. canis, one M. gypseum and one Trichophyton spp. From the 68 samples of cats, eight (11.76%) were positive to KOH, being 26 (38.23%) M. canis isolates. In M. canis infections in humans, the age rage was wide with predominance in women. In animals, M. canis isolates represented the most dermatophytic infection.     

Locking,intermittency, and bifurcations in a periodically driven pacemaker neuron: Poincaré maps and biological implications

Slowly adapting stretch receptor (SAO) pacemaker neurons, driven with periodic tugs, were analyzed by way of Poincaré mappings (Appendix). Two behaviors were apparent, i) Intermittency characterized previously unclear situations: discharges shifted irregularly between prolonged epochs where spike phases (relative to tugs) and intervals barely changed (slid), and brief bursts with marked variations (skipped), ii) Locking was well-known: phases and intervals remained almost fixed, regardless of the initiation. Changing frequencies, map domains with locking (ordered according to spikes/tugs ratios), alternated with intermittent ones. The best fit for any experimental map was a curve, not straight but certainly unidimensional, continuous and monotonic; it varied characteristically with frequency. This suggested relations called diffeomorphisms, implying periodicity and quasi-periodicity. Outcomes, expanding previous knowledge and meaningful biologically, were i)a precise, exhaustive behavior list (including between behavior transitions) and ii)a thorough understanding or model. This, in turn, provides norms for more specific models (single-variable ones suffice), constraints upon basic mechanisms (one variable, reflecting several real ones combined, should behave as the phase), and forecasts for future experimentation (e.g., unexamined tug frequencies and amplitudes).Supported by funds from CONACYT (PCEXCNA 040539) to ODM and a donation from Trent J. Wells Inc. to JPS     

Breeding system features and a novel method for locating floral nectar secretion in a South American nightshade (Jaltomata quipuscoae)

Abstract

The location of nectar secretion in flowers of Jaltomata has not been identified with certainty until now: removal of the corolla and androecium from one side of living flowers allowed us to see, in progress, nectar secretion by the ovarian nectary. We studied Jaltomata quipuscoae, a wild plant that grows in southern Peru and produces copious, red floral nectar. Unmanipulated flowers do not set fruit in a pollinator-free greenhouse, demonstrating lack of autogamy, but self-compatibility was demonstrated by manual self-pollinations leading to fruit-set. Anther dehiscence is staggered with the anthers of a flower dehiscing over hours on the same day. The corolla and nectar are UV-absorptive. Flowers last 4–10 days, are usually protogynous during the first day the corolla is open, and do not close for the night.     

Pastoralism in Northern Peru during Pre-Hispanic Times: Insights from the Mochica Period (100–800 AD) Based on Stable Isotopic Analysis of Domestic Camelids

Llama (Lama glama) and alpaca (Vicugna pacos) are the only large domesticated animals indigenous to the Americas. Pastoralism occupies a fundamental economic, social and religious role in Andean life. Today, camelid livestock are confined to the ecozone of the puna (above 3,500 masl), while their presence on the Pacific coast during pre-Hispanic times is attested by archaeological skeletal remains. This study aims to document herding practices on the northern Peruvian coast during the Early Intermediate Period (200 BC-600 AD) by gaining insights into diet, location of breeding and mobility of archaeological camelids from the funerary and ritual contexts of two Mochica sites, Uhle Platform in Huacas de Moche and El Brujo. The three first early years and the long-term life histories of the animals were documented by the combined bulk analysis of bone collagen (δ¹³C_col and δ¹⁵N_col) and bone structural carbonate (δ¹³C_bone and δ¹⁸O_bone) and the serial analysis of structural carbonate of molar tooth enamel (δ¹³C_enamel and δ¹⁸O_enamel). Mochica camelids were bred in the low and/or middle valleys, unlike their modern counterparts, who are restricted to highland puna C₃ pastures. Archaeological camelids had diverse and complex life histories, usually with substantial maize foddering. An ontogenetic switch in diet and possible residential mobility during the course of life were identified for some specimens. Although the inference of geographic origin from δ¹⁸O_bone and δ¹⁸O_enamel values was limited because of the lack of understanding of the influence of environmental and biological factors, tooth enamel analysis has great potential for exploring camelid herding practices and Andean pastoralism. Our study suggested that Mochica herders adapted their practices to the difficult lowland environment and that herding practices were varied and not restricted to breeding at higher altitudes. The role of maize in different aspects of the economic life of the Mochicas is also underlined.     

Real-time PCR method to quantify Sp245 strain of Azospirillum baldaniorum on Brachiaria grasses under field conditions

Plant and Soil - Soil microbiome roles in agriculture is becoming more and more important. This importance is also reflected on the way plants are seen: complex organisms formed by the plant itself...     

Expression of ERp5 and GRP78 on the membrane of chronic lymphocytic leukemia cells: association with soluble MICA shedding

MICA is a ligand of the activating receptor NKG2D, expressed by NK and T cells. MICA expression is induced in cancer cells favoring their elimination by the immune system; however, many advanced tumors shed soluble MICA (sMICA), which impairs NKG2D-mediated cytotoxicity. ERp5 and GRP78 are endoplasmic reticulum-resident proteins that are translocated to the surface of epithelial tumor cells where they interact with MICA and are involved in sMICA shedding. In this study, we analyze the role of ERp5 and GRP78 in sMICA shedding in chronic lymphocytic leukemia (CLL). Immunofluorescence and flow cytometry analyses showed that ERp5 and GRP78 were significantly expressed on the surface of B cells and leukemia cells, but they were not expressed on T cells. The expression of ERp5 and GRP78 was significantly higher in leukemia cells than in B cells from controls. ERp5 and GRP78 co-localized with MICA on the surface of leukemia cells and the levels of expression of ERp5 and GRP78 correlated with the level of expression of membrane-bound MICA in CLL patients. Associated with higher expression of membrane-bound ERp5 and GRP78, serum sMICA levels were approximately threefold higher in patients than in controls. Elevated sMICA levels in CLL patients were associated with the down-modulation of NKG2D surface expression on CD8 T cells. Finally, pharmacological inhibition of B cell lines and stimulated leukemia cells showed that ERp5 activity is involved in sMICA shedding in CLL. In conclusion, these results uncover a molecular mechanism which regulates MICA protein shedding and immune evasion in CLL.     

Biotechnologically relevant enzymes and proteins

The mold Aspergillus giganteus produces a basic, low molecular weight protein showing antifungal properties against economically important plant pathogens, the AFP (Antifungal Protein). In this study, we investigated the mechanisms by which AFP exerts its antifungal activity against Magnaporthe grisea. M. grisea is the causal agent of rice blast, one of the most devastating diseases of cultivated rice worldwide. AFP was purified from the extracellular medium of A. giganteus cultures. The AFP protein was found to induce membrane permeabilization in M. grisea cells. Electron microscopy studies revealed severe cellular degradation and damage of plasma membranes in AFP-treated fungal cells. AFP however failed to induce membrane permeabilization on rice or human HeLa cells. Furthermore, AFP enters the fungal cell and targets to the nucleus, as revealed by co-localization experiments of Alexa-labeled AFP with the SYTOX Green dye. Finally, AFP binds to nucleic acids, including M. grisea DNA. Our results suggest that the combination of fungal cell permeabilization, cell-penetrating ability and nucleic acid-binding activity of AFP determines its potent antifungal activity against M. grisea. These results are discussed in relation to the potential of the AFP protein to enhance crop protection against fungal diseases.     

The Arabidopsis AtNPR1 inversely modulates defense responses against fungal, bacterial, or viral pathogens while conferring hypersensitivity to abiotic stresses in transgenic rice

The nonexpressor of pathogenesis-related (PR) genes (NPR1) protein plays an important role in mediating defense responses activated by pathogens in Arabidopsis. In rice, a disease-resistance pathway similar to the Arabidopsis NPR1-mediated signaling pathway one has been described. Here, we show that constitutive expression of the Arabidopsis NPR1 (AtNPR1) gene in rice confers resistance against fungal and bacterial pathogens. AtNPR1 exerts its protective effects against fungal pathogens by priming the expression of salicylic acid (SA)-responsive endogenous genes, such as the PR1b, TLP (PR5), PR10, and PBZ1. However, expression of AtNPR1 in rice has negative effects on viral infections. The AtNPR1-expressing rice plants showed a higher susceptibility to infection by the Rice yellow mottle virus (RYMV) which correlated well with a misregulation of RYMV-responsive genes, including expression of the SA-regulated RNA-dependent RNA polymerase 1 gene (OsRDR1). Moreover, AtNPR1 negatively regulates the expression of genes playing a role in the plant response to salt and drought stress (rab21, salT, and dip1), which results in a higher sensitivity of AtNPR1 rice to the two types of abiotic stress. These observations suggest that AtNPR1 has both positive and negative regulatory roles in mediating defense responses against biotic and abiotic stresses.