Chromosome instability in intergeneric hybrids of Triticum aestivum;× tritordeum (amphiploid Hordeum chilense×Triticum turgidum) with high dosage of Ph1 gene of wheat

In somatic cells of intergencric hybrids Truicum uestirum (mono-isosomic 5BL, 2n=6x=4f)x trinordum 12n = 6x = 42, amphiploid Hordeum clulense x Triticum turgidnm)it was observed that high dosage of the long arm of 5B induced chromosome instability in hybrids 2n=42, in hybrids 2n=41 with only one dose of 5BL from the normal 5B genome of the teteaploed wheat, all cells have consistently 2n=41 chromosomes and no rmal 5B genome of the tetraploid wheat all cells have consistently 2n=41 plant differenttation in plants with 2n=42 which carry three doses of 5BL (one isochromosome 5BL and one 5B chromosome)most of the metaphase cells had 2n=42 chromosomes. However other cells in a reasonable frequency varying from 19% to 40% carried from 2n=6 to 2n=44. and showed marked desturbances in all phases of the cell cycle leading to final failure in plant development. It is suggested that the Ph1 geng of wheat. Located on 5BL regulates chromosome stability in the somatic cells of those hybrids

Degradação de compostos fenólicos por estirpes de Lactobacillus isoladas de águas russas

Comunicação apresentada no III Simpósio Nacional de Olvicultura que decorreu em Castelo Branco, na Escola Superior Agrária do Instituto Politécnico de Castelo Branco, de 289 a 31 de Outubro de 2003.As águas russas, principal resíduo da indústria de extracção do azeite, são caracterizadas por uma elevada carga orgânica poluente constituindo, por esta razão, um dos mais graves problemas ambientais dos países da bacia mediterrânea. São particularmente ricas em compostos fenólicos, lípidos e açúcares e apresentam teores mínimos de compostos azotados. O seu potencial biológico e energético é importante, pelo que se estudou a possibilidade de serem usadas como meio de cultura para produção de inóculos lácticos para a indústria de preparação de azeitona de mesa. Foram estudadas várias fontes de compensação de azoto, bem como vários tipos de meio, líquido ou sistema bifásico, com vista à maximização da capacidade de degradação de compostos fenólicos por bactérias lácticas (BL). Foram também estudados alguns dos factores de adaptação das BL às condições de stress fenólico. Concluiu-se que a degradação dos compostos fenólicos e a produção de ácido láctico depende do tipo e da concentração de azoto. Verificou-se que as BL possuem um mecanismo de adaptação ao stress fenólico, baseado em alterações dos seus componentes celulares

Stage - dependent centromere structure in mitosis and meiosis

[EN] Through the use of a silver staining technique three distinct regions can always be visualized in chromosomes:nucleolus organizer regions, centromere and telomere regions. The organization of the centromere region was studied in different phases of mitosis and meiosis. The centromere region was shown to be formed by an assembled dot-like structure with a market different complexity between mitotic and metaphase I chromosomes, being quadripartite in the former and bipartite in the latter. The nature of this difference is suggested to be related to the mechanism responsible to reductional division. The protein nature of these dots and their correspondence to the chromosome "core" and to the "scaffolding" is discussed. The presence of terminal dots in almost all telomeres and the existence of intercalar dots in some chromosomes are interpreted as being dependent on the individual phylogeny for each chromosome.[ES] Utilizando la técnica de tinción por el nitrato de plata, fue posible visualizar tres importantes regiones de los cromosomas de trigo panadero y de centeno: la centromérica, la telomérica y la del organizador nucleolar. Se observó que la región centrométrica era cosntituída por una estructura puntillada y densamente teñida cuya complejidad dependía de que los cromosomas estuviesen en la metafasis de mitosis o en la de la primera division de meiosis. En la última, la estructura del centrómetro era bipartida (Fig. 1A) mientras que en la primera se presentaba quadripartida (Fig. 1C, D). Se sugiere que esta estructura meiótica de los centrómeros pueda relacionarse con la división reducional que se sigue. Efectivamente los centrómeros son quadripartidos en la metafase ecuacional siguiente. Se discute la relación entre la constitución protéica de la estructura centromérica y los "core" y el "scaffolding" cromosómicos estudiados por varios autores. También se discute el origen de los puntos teloméricos e intercalares observados en los cromosomas cuando están teñidos por esta técnica.Peer reviewe

Seawater carbonate chemistry and endosymbiont density, photosynthesis and net calcification rates of reef-building coral Pocillopora damicornis

Ocean acidification is a growing threat to coral growth and the accretion of coral reef ecosystems. Corals inhabiting environments that already endure extreme diel pCO2 fluctuations, however, may represent acidification-resilient populations capable of persisting on future reefs. Here, we examined the impact of pCO2 variability on the reef-building coral Pocillopora damicornis originating from reefs with contrasting environmental histories (variable reef flat versus stable reef slope) following reciprocal exposure to stable (218 ± 9) or variable (911 ± 31) diel pCO2 amplitude (μtam) in aquaria over eight weeks. Endosymbiont density, photosynthesis and net calcification rates differed between origins but not treatment, whereas primary calcification (extension) was affected by both origin and acclimatization to novel pCO2 conditions. At the cellular level, corals from the variable reef flat exhibited less intracellular pH (pHi) acidosis and faster pHi recovery rates in response to experimental acidification stress (pH 7.40) than corals originating from the stable reef slope, suggesting environmental memory gained from lifelong exposure to pCO2 variability led to an improved ability to regulate acid–base homeostasis. These results highlight the role of cellular processes in maintaining acidification resilience and suggest that prior exposure to pCO2 variability may promote more acidification-resilient coral populations in a changing climate