Identificación molecular y diversidad genética de las especies de nematodos Globodera rostochiensis y G. pallida en regiones productoras de papa de Guatemala / Molecular identification and genetic diversity of the species of nematodesGlobodera rostochiensisandG. pallidain potato growing regions of Guatemala

En Guatemala, la producción del cultivo de papa se ve afectada por los nematodos Globodera rostochiensis y Globo-dera pallida. La capacidad de ambas especies para formar quistes complica su control y provoca el aumento de sus poblaciones. En Guatemala se reporta la presencia de ambas especies de nematodos por identificación morfológica, sin embargo, no se ha realizado una confirmación molecular. Este es el primer estudio para validar la presencia de ambas especies de nematodos por PCR múltiple y la determinación de la diversidad y estructura genética de las poblaciones utilizando marcadores moleculares. Se realizaron muestreos en cuatro departamentos productores de papa del país. La identificación por PCR se realizó con el cebador común ITS5 y los cebadores PITSr3 específico para G. rostochiensisy PITSp4 para G. pallida. La caracterización molecular se realizó con el marcador AFLP. Se confirmó la presencia de las dos especies de nematodos en los cuatro departamentos. Los índices de diversidad Shannon y heterocigosidad esperada revelaron mayor diversidad genética en G. rostochiensis (H = 0.311, He = 0.301) que en G. pallida (H = 0.035, He = 0.223). Los métodos NJ, DAPC y PCA exhibieron una débil estructura entre las poblaciones de ambas especies de nematodos. Los resultados sugieren un patrón de dispersión desde Quetzaltenango hacia el resto del país, atribuido a la comercialización de semilla contaminada con nematodos. Se sugiere promover programas de socialización sobre los beneficios del uso de semilla certificada, además de constantes monitoreos moleculares para un diagnóstico certero de ambas especies de nematodos.

In Guatemala, potato crop production is affected by the nematodes Globodera rostochiensis and Globodera pallida. The ability of both species to form cysts complicates their control and causes an increase in their populations. In Guatemala, both species of nematodes have been reported by morphological identification; however, molecular confirmation has not been carried out. It is the first study to validate the presence of both nematode species by multiplex PCR and determine the diversity and genetic structure of the populations using molecular markers. Sampling was carried out in four pota-to-producing departments of the country. PCR identification was performed with the common primer ITS5 and the primers PITSr3 specific for G. rostochiensis and PITSp4 for G. pallida. We performed molecular characterization with the AFLP marker. We confirmed the presence of the two nematode species in the four departments. Shannon diversity and expected heterozygosity indices revealed higher genetic diversity in G. rostochiensis (H = 0.311, He = 0.301) than in G. pallida (H = 0.035, He = 0.223). The NJ, DAPC, and PCA methods exhibited weak structure among populations of both nematode species. The results suggest a dispersal pattern from Quetzaltenango to the rest of the country, attributed to the commer-cialization of seed contaminated with nematodes. We suggest promoting socialization programs on the benefits of using certified seeds and constant molecular monitoring for an accurate diagnosis of both species of nematodes.

First record of Pseudoterranova decipiens (Nematoda, Anisakidae) infecting the Red spot emperor Lethrinus lentjan in the Red Sea / Primeiro registro de Pseudoterranova decipiens (Nematoda, Anisakidae) infectando o imperador da mancha vermelha Lethrinus lentjan no Mar Vermelho

Abstract The current parasitological study was carried out to investigate helminth parasites infecting the Red spot emperor Lethrinus lentjan inhabiting Hurghada City at the Gulf of Suez, Red Sea, Egypt. Third-stage larvae of nematode parasite was isolated from the intestine as well as body cavity of the examined fish. Light and scanning electron microscopy revealed that this parasite belonged to Anisakidae family within the genus Pseudoterranova. The present species is named Pseudoterranova decipiens based on the presence of triangular mouth aperture with prominent boring teeth and soft swellings of the cuticle, long muscular esophagus, ventrally excretory pore, and narrow transverse slit of anal opening followed by a short mucron. The morphological characteristics of this species were confirmed by molecular analysis of 18S rDNA gene region of the present parasite. It demonstrated a close identity ≥89% with taxa under family Anisakidae, 85% with Raphidascarididae, and 79-84% with Toxocaridae. A preliminary genetic comparison between gene sequence of the present parasite and other oxyurid species placeed it as a putative sister taxon to other Pseudoterranova decipiens described previously. This study demonstrated that the 18S rDNA gene region of Pseudoterranova decipiens yielded a unique sequence that confirmed its taxonomic position in Anisakidae.

Resumo O presente estudo parasitológico foi realizado para investigar os helmintos parasitos que infectam o peixe imperador Lethrinus lentjan, que habita a cidade de Hurghada no Golfo de Suez, Mar Vermelho, no Egito. Larvas de terceiro estágio de parasitos nematoides foram isoladas do intestino e da cavidade do corpo do peixe examinado. Microscopia eletrônica de luz e de varredura revelou que este parasita pertence à família Anisakidae dentro do gênero Pseudoterranova. A espécie atual é denominada Pseudoterranova decipiens baseada na presença de abertura triangular da boca com dentes proeminentes chatos e inchaços moles da cutícula, esôfago muscular longo, poro ventralmente excretor e fenda transversal estreita da abertura anal seguida por um mucron curto. As características morfológicas desta espécie foram confirmadas pela análise molecular da região do gene 18S rDNA do presente parasito. Demonstrou uma identidade próxima ≥89% com taxa sob família Anisakidae, 85% com Raphidascarididae, e 79-84% com Toxocaridae. Uma comparação genética preliminar entre a sequência genética do presente parasito e outras espécies de oxiurídeos coloca-o como um taxon irmão putativo para outros Pseudoterranova descritos anteriormente. Este estudo demonstra que a região do gene 18S rDNA de Pseudoterranova decipiens produz uma sequência única que confirma sua posição taxonômica em Anisakidae.

Phenylpropanoid enzymes, phenolic polymers and metabolites as chemical defenses to infection of Pratylenchus coffeae in roots of resistant and susceptible bananas (Musa spp.).

Activity differences of the first (phenylalanine ammonia lyase, PAL) and the last (cinnamyl alcohol dehydrogenase, CAD) enzymes of phenylpropanoid pathway in the roots of resistant (Yangambi Km5 and Anaikomban) and susceptible (Nendran and Robusta) banana cultivars caused by root lesion nematode, Pratylenchus coffeae, were investigated. Also, the accumulation of phenolics and deposition of lignin polymers in cell walls in relation to resistance of the banana cultivars to the nematode were analyzed. Compared to the susceptible cultivars, the resistant cultivars had constitutively significantly higher PAL activity and total soluble and cell wall-bound phenolics than in susceptible cultivars. The resistant cultivars responded strongly to the infection of the nematode by induction of several-time higher PAL and CAD enzymes activities, soluble and wall-bound phenolics and enrichment of lignin polymers in cell wall and these biochemical parameters reached maximum at 7th day postinoculation. In addition, profiles of phenolic acid metabolites in roots of Yangambi Km5 and Nendran were analyzed by HPLC to ascertain the underlying biochemical mechanism of bananas resistance to the nematode. Identification and quantification of soluble and cell wall-bound phenolic acids showed six metabolites and only quantitative, no qualitative, differences occurred between the resistant and susceptible cvs. and between constitutive and induced contents. A very prominent increase of p-coumaric, ferulic and sinapic acids, which are precursors of monolignols of lignin, in resistant cv. was found. These constitutive and induced biochemical alterations are definitely the chemical defenses of resistant cvs. to the nematode infection.

Comparison of whole-genome amplifications for microsatellite genotyping of Rotylenchulus reniformis

Currently, a large number of microsatellites are available for Rotylenchulus reniformis (reniform nematode); however, two barriers exist for genotyping samples from different geographical areas. The limited amount of nucleic acids obtained from single nematodes which would require their multiplication to obtain enough DNA for testing; and the strictly regulated transport of live samples and multiplication in greenhouse for being a plant pathogen. Whole-genome amplification (WGA) of samples consisting of one and five dead gravid females with their associated egg masses was successfully performed on disrupted tissue using three commercial kits. DNA yield after WGA ranged from 0.5 to 8 ug and was used to test 96 microsatellite markers we previously developed for the reniform nematode. The results were compared to those of fingerprinting the original population (MSRR03). Out of 96 markers tested, 71 had amplicons in MSRR03. Using WGA of single gravid females with their associated egg masses, 86-93 percent of the alleles found on MSRR03 were detected, and 87-88 percent of the alleles found on MSRR03 when using WGA of samples composed of five gravid females with their associated egg masses as template. Our results indicate that reniform nematode samples as small as a single gravid female with her associated egg mass can be used in WGA and direct testing with microsatellites, giving consistent results when compared to the original population.

Pre-mRNA trans-splicing: from kinetoplastids to mammals, an easy language for life diversity

Since the discovery that genes are split into intron and exons, the studies of the mechanisms involved in splicing pointed to presence of consensus signals in an attempt to generalize the process for all living cells. However, as discussed in the present review, splicing is a theme full of variations. The trans-splicing of pre-mRNAs, the joining of exons from distinct transcripts, is one of these variations with broad distribution in the phylogenetic tree. The biological meaning of this phenomenon is discussed encompassing reactions resembling a possible noise to mechanisms of gene expression regulation. All of them however, can contribute to the generation of life diversity.

Diversidade genética de cepas do fungo Arthrobotrys spp. predador de nematóides por RAPD e PCR-RFLP do rDNA / Genetic diversity of nematode preadacius fungi Arthrobotrys spp. by RAPD and rDNA Pcr-RFLP

A diversidade genética de seis cepas de Arthrobotrys conoides, três de A oligospora e sete de A robusta foi avaliada por meio de RAPD. A amplificação resultou em um total de 107 fragmentos de ONA polimórficos, utilizando-se 11 oligonucleotídeos. As distâncias genéticas variaram de 9 a 83%, quando analisadas em conjunto, demonstrando grande diversidade genética das cepas dessas três espécies. Por meio dessas análises, pôde-se diferenciar as cepas A51 (A robusta) e A78 (Aconoides) das suas respectivas espécies. Além desses, a cepa A183 (Aoligospora) também se diferenciou de sua espécie agrupando-se com cepas de A robusta. A variação dentro do espaçador interno transcrito (ITS) do rONA de seis cepas de Aconoides e sete de Arobusta foi analisada por PCR seguida pela análise de "restriction fragment length polimorphism" (RFLP). Duas cepas fúngicas, A51 e A78, apresentaram polimorfismo de tamanho de fragmentos dentro de suas respectivas espécies. Os produtos da amplificação da região ITS foram hidrolisados com diferentes endonucleases de restrição. Análises de agrupamento, baseadas nos fragmentos de ONA de restrição, separaram as cepas em três distintos grupos: o Grupo 1, que contém aquelas pertencentes à espécie Aconoides, exceto a cepa A78; o Grupo 2, que contém as cepas da espécie Arobusta, exceto a A51; e o Grupo 3, formado pelas cepas A78 e A51, sugerindo uma nova análise na sua classificação

Recent advances in diagnosis of filarial infections.

Improved diagnostic methods for human filariasis are needed to facilitate surveillance activities, to monitor control efforts and to evaluate new drugs and vaccines. Currently, diagnosis of filarial infections largely depends upon detection of worms themselves, principally of microfilariae in blood or skin. In many infected people with lymphatic filariae, microfilariae (MF) are not detectable in blood, and removal of skin snips for detection of microfilariae in onchocerciasis seems a rather primitive technique. In addition, because the clinical manifestations of filariae vary greatly between individuals, an ideal diagnostic test would not only reveal individuals that are infected or have been exposed to infection, but would also differentiate between various clinical manifestations that the lymphatic-dwelling parasites, in particular, induce in the infected population. This is important because the pathological reactions induced following treatment with diethylcarbamazine vary with the clinical picture induced by the lymphatic filariae. They are certainly a major problem in onchocerciasis. Recent advances in biotechnology have started revolutionizing the diagnosis of filarial parasites not only in the host but also in their vectors. Monoclonal antibodies have been developed that are specific for detection of circulating antigens in lymphatic filariasis. Species-specific DNA probes have been developed for Brugia malayi, Wuchereria bancrofti, Onchocerca volvulus, and Loa loa. Diagnostic antigens have been obtained by cloning parasite DNA that codes for proteins recognized by infected individuals with only certain species of filariae. Recombinant antigens (rAgs) are available today which detect prepatent infections in onchocerciasis. Several laboratories developing new diagnostic tests for filariasis are currently evaluating these tests in the field with the collaboration of parasitologists, epidemiologists, and vector biologists.