Lanthanum content and effects on growth, gas exchanges, and chlorophyll index in maize plants / Teor de lantânio e efeitos no crescimento, trocas gasosas e teor de clorofila em plantas de milho

Rare earth elements, such as lanthanum (La), have been applied to agriculture via fertilizers, aiming to increase the productivity and crop quality, such results observed mainly in China. However, the knowledge about the effect of La on maize growth, as well as for other species, despite the growing interest it is still limited. The aim of this study was to evaluate the effects of La on maize growth, La content,photosynthetic rate and chlorophyll content in maize plants in response to La treatment (0, 25, 50, 100, 150, 300 and 600 μM) in nutrient solution for three weeks. The plants were placed in geminated pots using a split-root technique. One of the pots in the geminated set was filled with a complete nutrient solution without La, while another was filled with a nutrient solution without phosphorus but containing different concentrations of La. It was verified that roots of maize plants can accumulate approximately sixty percent more La than shoots. Moreover, low La concentrations stimulated an increase in chlorophyll index,resulting in a slight increase in shoot biomass. At higher levels, La didn’t reduce growth but caused adecrease in both photosynthetic rate and chlorophyll index.

Elementos terra rara, como lantânio (La), são aplicados à agricultura via fertilizantes, com oobjetivo de aumentar a produtividade e a qualidade das culturas agrícolas, fato observado principalmente naChina. Entretanto, o conhecimento sobre o efeito de La no crescimento do milho, bem como para outrasculturas agrícolas, ainda é limitado apesar do interesse crescente. O presente estudo objetivou avaliar oefeito da aplicação de La sobre o crescimento, teor de La, fotossíntese e teor de clorofila em plantas demilho, expostas a concentrações crescentes de La (0, 25, 50, 100, 150, 300 e 600 μM) em solução nutritivapor três semanas. As plantas foram colocadas em vasos geminados usando uma técnica de raiz divisória.Um dos potes no conjunto geminado foi preenchido com solução nutritiva completa que não continha La,enquanto outra foi preenchida com solução nutritiva sem fósforo, mas contendo diferentes concentraçõesde La. Foi verificado que as raízes das plantas de milho podem acumular sessenta por cento mais La quandocomparado à parte aérea. Além disso, as baixas concentrações de La estimularam o aumento do teor declorofila, resultando em um aumento na biomassa da parte aérea. Em concentrações mais elevadas, aaplicação de La não reduziu o crescimento das plantas de milho, mas causou diminuição na taxafotossintética e no índice de clorofila.

Photosynthesis at the far-red region of the spectrum in Acaryochloris marina

Acaryochloris marina is an oxygenic cyanobacterium that utilizes far-red light for photosynthesis. It has an expanded genome, which helps in its adaptability to the environment, where it can survive on low energy photons. Its major light absorbing pigment is chlorophyll d and it has α-carotene as a major carotenoid. Light harvesting antenna includes the external phycobilin binding proteins, which are hexameric rods made of phycocyanin and allophycocyanins, while the small integral membrane bound chlorophyll binding proteins are also present. There is specific chlorophyll a molecule in both the reaction center of Photosystem I (PSI) and PSII, but majority of the reaction center consists of chlorophyll d. The composition of the PSII reaction center is debatable especially the role and position of chlorophyll a in it. Here we discuss the photosystems of this bacterium and its related biology.

Influence of municipal solid waste compost [MSWC] on the growth and yield of green gram Vigna radiate [L wilczek], fenugreek [Ttrigonella foenum-graecum L.] and on soil quality

Pot culture experiments were carried out to study the effect of characterized municipal solid waste compost [MSWC] amendments [0, 50,100,250, 500, 750 and 1000 g] with garden soil [6 kg] on the growth and the yield of green gram [Vigna radiata [L] wilczek] and fenugreek [Trigonellafoenum-graecum L.] as well as changes on soil quality. The growth and the yield of green gram and fenugreek were enhanced by MSWC application upto 500 g. Soil amended with > 500 g MSWC inhibited the plants biometric parameters neither with-significantly nor without-significantly suggest a possible toxic effects to both plants. No dosage effect was detected for total chlorophyll synthesized, except green gram grown in 1000 g of MSWC amendments. Compared with control, percentage of protein was increased significantly upto 250 g for green gram and 500 g for fenugreek. A significant reduction in percentage of carbohydrates was observed above 750 g of MSWC exposure for green gram and above 500 g for fenugreek. There was no specific trend and significant changes were observed in percentage of reducing sugars in both plants except green gram exposed to 50 g MSWC exposure. There was no significant difference in all plant yield parameters of both plants except fenugreek seed weight in 250 g MSWC amendment. Generally, chemical parameters of soil are improved by the addition of MSWC, after 90 d of experimental period

Crecimiento y producción de metabolitos de la cianobacteria marina Synechococcus sp. (Chroococcales) en función de la irradiancia

Growth and metabolite production of the marine cyanobacterium Synechococcus sp. (Chroococcales) in function to irradiance. Changes in salinity, temperature and irradiance during wet and dry seasons have induced metabolic versatility in cyanobacteria from saline environments. Cyanobacteria from these environments have biotechnological potential for the production of metabolites with pharmaceutical and industrial interest. We studied the growth, dry mass and metabolite production of the cyanobacterium Synechococcus sp. MOF-03 in function of irradiance (78, 156 and 234 µmol q m-2 s-1). All batch cultures were maintained by triplicate in constant aeration, 12:12 h photoperiod, 30 ±2ºC and 35‰. Maximum values of protein, carbohydrates and lipids, of 530.19 ±11.16, 408.94 ±4.27 and 56.20 ±1.17 µg ml-1, respectively, were achieved at 78 µmol q m-2 s-1. Pigments, analyzed by HPLC, showed maximum values at 78 µmol q m-2 s-1 for chlorophyll a with 7.72 ±0.16 µg ml-1, and at 234 µmol q m-2 s-1 for ß-carotene and zeaxanthin with 0.70 ±0.01 and 0.67 ±0.05 µg ml-1. Chlorophyll a:ß-carotene ratio decreased from 17.15 to 6.91 at 78 and 234 µmol q m-2 s-1; whereas ß-carotene:zeaxanthin ratio showed no changes between 78 and 156 µmol q m-2 s-1, around 1.21, and decreased at 234 µmol q m-2 s-1, to 1.04. Also, this cyanobacterium produced the greatest cell density and dry mass at 156 µmol q m-2 s-1, with 406.13 ±21.74 x106 cell ml-1 and 1.49 ±0.11 mg ml-1, respectively. Exopolysaccharide production was stable between 156 y 234 µmol q m-2 s-1, around 110 µg ml-1. This Synechococcus strain shows a great potential for the production of enriched biomass with high commercial value metabolites. Rev. Biol. Trop. 56 (2): 421-429. Epub 2008 June 30.

Las cianobacterias de ambientes salinos presentan una versatilidad metabólica inducida por los cambios de salinidad, temperatura e irradiancia, durante los períodos de sequía y lluvias. Por ello es importante la búsqueda en estos ambientes de cianobacterias con potencial biotecnológico para la producción de metabolitos de interés farmacéutico e industrial. Se reporta el crecimiento, masa seca y producción de metabolitos de la cianobacteria Synechococcus sp. MOF-03 en función de la irradiancia (78, 156 y 234 µmol q m-2 s-1). Los cultivos discontinuos por triplicado, fueron mantenidos con aireación constante, fotoperiodo 12:12 h, 30 ±2ºC y a 35‰. Los máximos valores de proteínas, carbohidratos y lípidos de 530.19 ±11.16, 408.94 ±4.27 y 56.20 ±1.17 µg ml-1 respectivamente, fueron obtenidos a 78 µmol q m-2 s-1. Los pigmentos, analizados por HPLC, mostraron los máximos a 78 µmol q m-2 s-1 para clorofila a con 7.72 ±0.16 µg ml-1; y a 234 µmol q m-2 s-1 para ß-caroteno y zeaxantina con 0.70 ±0.01 and 0.67 ±0.05 µg ml-1. La relación clorofila a:ß-caroteno disminuyó de 17.15 hasta 6.91 a 78 y 234 µmol q m-2 s-1; mientras que la relación ß-caroteno:zeaxantina se mantuvo sin cambios entre 78 y 156 µmol q m-2 s-1, con cerca de 1.21 y disminuyó a 234 µmol q m-2 s-1 a 1.04. La cianobacteria produjo la mayor densidad celular y masa seca a 156 µmol q m-2 s-1, con 406.13 ±21.74 x106 cel ml-1 y 1.49 ±0.11 mg ml-1 respectivamente. La producción de exopolisacáridos se mantuvo alrededor de 110 µg ml-1 entre 156 y 234 µmol q m-2 s-1. Así, esta cepa de Synechococcus muestra un gran potencial para la producción de biomasa enriquecida con metabolitos de alto valor comercial.

Antisense expression of a gene encoding a calcium-binding protein in transgenic tobacco leads to altered morphology and enhanced chlorophyll.

Entamoeba histolytica contains a novel calcium-binding protein like calmodulin,which was discovered earlier,and we have reported the presence of its homologue(s)and a dependent protein kinase in plants.To understand the functions of these in plants,a cDNA encoding a calcium-binding protein isolated from Entamoeba histolytica (EhCaBP)was cloned into vector pBI121 in antisense orientation and transgenic tobacco plants were raised.These plants showed variation in several phenotypic characters,of which two distinct features,more greenness and leaf thickness,were inherited in subsequent generations.The increase in the level of total chlorophyll in different plants ranged from 60% to 70%.There was no major change in chloroplast structure and in the protein level of D1,D2,LHCP and RuBP carboxylase.These morphological changes were not seen in antisense calmodulin transgenic tobacco plants,nor was the calmodulin level altered in EhCaBP antisense plants.

Carotenogénesis de cinco cepas del alga Dunaliella sp. (Chlorophyceae) aisladas de lagunas hipersalinas de Venezuela / Carotenogenesis of five strains of the algae Dunaliella sp. (Chlorophyceae) isolated from Venezuelan hypersaline lagoons

Se realizaron cultivos discontinuos (medio Algal con 0.5 mM de NaNO3 y 27% de NaCl) de cinco cepas de Dunaliella sp., aisladas de diferentes lagunas hipersalinas de Venezuela (Araya, Coche, Peonía, Cumaraguas y Boca Chica) y una cepa de referencia (Dunaliella salina LB1644). Los bioensayos se mantuvieron a 25 ± 1 °C con aireación constante, fotoperiodo 12:12 y dos intensidades luminosas (195 y 390 µE.m-2.s-1) durante 30 días. El crecimiento celular se determinó diariamente mediante conteo celular en cámara de Neubaüer. La clorofila a y los carotenoides totales se analizaron al final del ensayo. Las mayores densidades celulares correspondieron a los ensayos de menor intensidad luminosa. La cepa que alcanzó la mayor densidad celular fue la aislada de Boca Chica (8 x106 y 2.5 x106 cel.ml-1 a 195 y 390 µE.m-2.s-1, respectivamente). El incremento de la intensidad luminosa en los cultivos produjo una disminución significativa de las tasas de crecimiento en todas las cepas. Los carotenoides totales por volumen fueron mayores a 390 µE.m-2 .s-1; siendo las cepas de referencia LB1644, Coche y Araya las que produjeron mayor cantidad (38.4; 32.8 y 21.0 µg.ml-1, respectivamente). El contenido de carotenoides totales por célula en los dos tratamientos fue significativamente diferente, obteniéndose la mayor concentración a 390 µE.m-2.s-1. Las cepas LB1644 y Coche fueron las que produjeron los valores más altos de carotenos (137.14 y 106.06 pg.cel-1, respectivamente). La cepa LB1644 presentó la mayor relación carotenoides totales:clorofila a (20:1) a 195 µE.m-2.s-1, mientras que en la cepa Coche no se evidenciaron diferencias significativas entre las dos intensidades (15:1). El resto de las cepas mostraron relaciones inferiores a uno. Nuestros resultados sugieren que las cepas Coche y Araya pueden ser potencialmente utilizadas en la biotecnología de producción de carotenoides

We evaluated discontinuous cultures (Algal medium at 0.5 mM of NaNO3 , and 27% NaCl) of five strains of Dunaliella sp. isolated from Venezuelan hypersaline lagoons (Araya, Coche, Peonía, Cumaraguas, and Boca Chica) and one strain from a reference collection (Dunaliella salina, LB1644). Cultures were maintained to 25±1 °C, with constant aeration, photoperiod 12:12, and two light intensities (195 and 390 µE.m-2 .s-1) during 30 days. Cell count was recorded on a daily basis using a Neubaüer camera. Totals of chlorophyll a and carotenoids were measured at the end of the experiment. The largest cellular densities were measured during the smallest light intensities. The strain with the largest cellular density was isolated from Boca Chica (8 x106 and 2.5 x106 cel.ml-1 a 390 and 195µE.m-2 .s-1, respectively). The increment of light intensity produced a significant reduction of growth rates in all strains. Totals of carotenoids by volume were as large as 390 µE.m-2 .s-1. Strains LB1644, from Coche and Araya were those that produced the largest amount of carotenoids (38.4; 32.8 and 21.0 µg.ml-1 , respectively). Differences total carotenoids by cell between treatments were significant. The largest concentration was 390 µE.m-2 .s-1 . The strains LB1644 and Coche produced the highest values of carotenes (137.14 and 106.06 pg.cel-1, respectively). Differences in the relation carotenoid:chlorophyll a between the strains at various light intensities was significant. Strains LB1644 presented the largest value of the relation carotenoids:chlorophyll a (20:1) at 195 µE.m-2 .s-1. No significant differences were detected in the strain Coche (15:1). All the other strains showed relations lower than one. Our results suggest that the strains of Coche and Araya show potential to be used in the biotechnology of carotenoids production

Inhibition of chlorophyll biosynthesis by mercury in excised etiolated maize leaf segments during greening: effect of 2-oxoglutarate.

Mercury (0.01-1.0 mM) inhibited chlorophyll formation in greening maize leaf segments. However, supplementing incubation medium with 2-oxoglutarate, maintained substantially higher level of chlorophyll in absence of metal after an initial period of 8 hr. On preincubation of leaf segments with HgCl2, per cent inhibition of chlorophyll synthesis by metal was same in the presence and absence of 2-oxoglutarate. Supply of 2-oxoglutarate (0.1-10.0 mM) exerted concentration dependent effect on chlorophyll formation in absence or presence of metal. Increase in delta-amino levulinic acid dehydratase as well as NADH-glutamate synthase activity and decrease in NADH-glutamate dehydrogenase activity by 2-oxoglutarate in the presence of Hg suggested that glutamate for delta-amino levulinic acid synthesis could be made available from NH4+ assimilation via., glutamine synthetase/glutamate synthase pathway during mercury toxicity.

Effect of dust contamination on soil, leaf chemical composition and fruit quality of piscium guava L.

The aim of the present study is to evaluate the effect of dust contamination at different distances on soil, leaf chemical composition, fruit set and fruit quality of Psidium guajava L. The study revealed that, Ni. Pb and Cd contents in soil decreased with increasing distance from the source of dust and with increasing soil depth. In leaves. P, Na, K, Ca and Mg exhibited an appreciable increase in their contents in trees adjacent to the road. Chlorophyll contents showed a slight increase and the variation in total available carbohydrates was insignificant as compared with trees distant from the road. In the two studied seasons [1990 and 1991], the average fruit set, mature fruits and fruit weight was signifcantly lower in trees adjacent the road. The reverse was true for core/flesh ratio. The contents of citric acid and vitamin C were significantly higher in fruits adjacent and distant from the road respectively. Concerning the heavy metals content in leaves and fruit parts [flesh and core], the results indicated that Mn, Ni, Pb and Cd in leaves and Ni, Pb and Cd in fruit parts significantly higher in trees adjacent the road