The effects of Anabaena spiroides (Cyanophyceae) exopolysaccharide on copper toxicity to Simocephalus serrulatus (Cladocera, Daphnidae)

1. This work investigated the consumption of a microalgal (Anabaena spiroides) exopolysaccharide by the cladoceran Simocephalus serrulatus (Cladocera, Daphnidae) and its effect on copper toxicity. 2. Total organic carbon concentration was used to quantify the microalgal exopolysaccharide. Both copper‐complexed exopolysaccharides and copper‐free exopolysaccharides were taken up by S. serrulatus. 3. A reduction of free copper ions was obtained in the presence of A. spiroides exopolysaccharide. Copper toxicity (EC₅₀) and zooplankton concentrations were inversely correlated to exopolysaccharide concentration in experimental media. 4. An increase of free copper ions in experimental media was obtained after exopolysaccharide consumption, suggesting that S. serrulatus excreted copper to the surrounding environment.     

Case–control association study of polymorphisms in the angiotensinogen and angiotensin-converting enzyme genes and coronary artery disease and systemic artery hypertension in African-Brazilians and Caucasian-Brazilians

The rennin–angiotensin–aldosterone system (RAAS) is a critical pathway in regulating blood pressure and salt/water homeostasis, possessing an intimate relationship with the development of systemic artery hypertension (SAH). Once hypertension is considered a risk factor for coronary artery disease (CAD), the RAAS is also related to this pathology. This investigation aimed to analyse if the frequencies of AGT M235T (rs699) and ACE I/D (rs4646994) polymorphisms are associated with CAD and SAH in African-Brazilians and Caucasian-Brazilians. In this study we analysed 714 subjects who underwent coronary angiography to detect obstructive lesions and CAD, as well as blood pressure measurement and SAH, grouped according to ethnicity: 266 African-Brazilians and 448 Caucasian-Brazilians. Among CAD and SAH cases and controls, the genotype and allele frequencies of ACE I/D polymorphism were similar in both ethnic groups. The AGT 235TT genotype and 235T allele frequencies were higher in SAH cases (32%, 54.7%) versus controls in Caucasian-Brazilians (19.8%, 46.4%; P= 0.038, P= 0.031, respectively). The AGT 235TT (OR = 1.8; P= 0.028) demonstrated to be an independent factor risk in a multivariate logistic regression increasing SAH risk in Caucasians but not in African-Brazilians. In summary, AGT M235T polymorphism was associated with SAH risk in Caucasian-Brazilians, and no association was detected with CAD. No association was also observed in ACE I/D polymorphism either in CAD or SAH in African-Brazilians and Caucasian-Brazilians.     

Nutritional Requirements of Blastocrithidia culicis,a Trypanosomatid with an Endosymbiont1

ABSTRACT. The symbiont-containing Blastocrithidia culicis from Aedes vexans, unlike most lower trypanosomatids cultivated in defined media, require only three amino acids: methionine, histidine, and arginine; only three vitamins: thiamin, nicotinamide, and riboflavin; and neither heme nor purine. The bacterium-like endosymbiont presumably provides the trypanosomatid's other essential nutrients.     

A new genus of African Karniellina (Orthoptera,Tettigoniidae, Conocephalinae,Conocephalini): integrating morphological,molecular and bioacoustical data

Melanoscirtes gen.n. is established within Karniellina. The members of this subtribe are small conocephaline bush crickets, confined to Africa. Melanoscirtes is erected on Phlesirtes kibonotensis, a species restricted to forest clearings and forest edge in the submontane and montane zones of Mt. Kilimanjaro. A subspecies, M. kibonotensis uguenoensis, is described from the North Pare mountains, a mountain range of the Eastern Arc adjacent to Mt. Kilimanjaro. Further species of Melanoscirtes occur on other mountain ranges of the northern branch of the Eastern Arc mountains of northern Tanzania and southern Kenya. The South Pare mountains harbour M. shengenae; the West Usambaras, M. usambarensis, and the Taita Hills, M. taitensis. All species and subspecies of Melanoscirtes exhibit a similar morphology and occupy analogous habitats on the respective mountains. The song patterns for all species found within this genus are very similar, and this, together with evidence from molecular data, suggests that allopatric speciation is the reason for the biogeographic pattern found in this genus. A key for the subspecies and species of Melanoscirtes is provided.     

Seasonal changes in a cactus‐hoverfly (Diptera: Syrphidae) network

1. We analysed a cacti‐syrphid community focusing on the exploitation of decaying cacti resources by the flies, i.e. if exploitation exhibited a nested topology as a structural pattern, or whether it was temporally random. If availability of cactus resources was predictable during the rainy season, it would then be exploited by a more structured community, or as resource availability would be unpredictable during the dry season, we should expect it to be exploited by a random community. 2. We registered 12 Copestylum species (9 in dry and 11 in rainy season). Four cactus species were recorded per season, three were shared between seasons. 3. The community of Copestylum larvae in the rainy season was not randomly assembled but highly nested, revealing a highly structured pattern of resource use. It exhibited a random organization for the dry season. The high nestedness value obtained for the rainy season suggests that factors along with competition must play a major role in determining community structure. 4. Succession in the cacti‐syrphid community mediated by microorganisms involved in necrosis is an important factor structuring nested subsets. The studied networks were small, which may limit the power of the analysis, and strong conclusions could also be limited.     

Effect of Nitrogen Supply on the Photosynthetic Performance of Leaves from Coffee Plants Exposed to Bright Light

Although Coffea arabica L. grows naturally in shaded habitats,it can be cultivated under high light intensity, but not withoutsevere photoinhibition mainly during the period of transferfrom the nursery into the field. The present work examines someof the changes in the photosynthetic performance induced byexposure to high light and the possibility of using enhancednitrogen levels to overcome photoinhibition. For that purpose,young plants of Coffea arabica L. (cv. Catuai) grown in a shadedgreenhouse were treated with 0, 1 and 2 mmol of nitrogen and4 weeks later exposed to full solar irradiation, outside. Visible damage due to exposure to full sunlight appeared within2 d in all plants, resulting in a reduced photosynthetic leafarea and drastic shedding of leaves in the unfertilized plants.These effects were considerably less in plants with the highestN dose. After 130 d of exposure, there was 100% mortality inplants receiving no extra nitrogen, compared with 30% in theplants treated with 2 mmol nitrogen. Photosynthesis rates, leafconductance and transpiration presented minimum values after4 d of light stress. Large changes in the photosynthetic capacity(measured at high CO₂ concentration and high light intensity),quantum efficiency and fluorescence yield (F_v/F_m) indicate thatnet photosynthesis rate in the air had been reduced by bothstomatal closure and by changes at the photochemical level.All indicators show that N-fertilized plants were less affectedby photoinhibition. Key words: Coffee plant, nitrogen, photoinhibition, photosynthesis     

Early Seedling Growth in Normal and Opaque-2 Zea mays L. cv. Maya: I. COMPOSITION AND MOBILIZATION OF THE ENDOSPERM PROTEIN RESERVE

Grain of op-2 Maya have a higher total protein content in bothendosperm and germ than normal maize. In large grain, differencesin total grain protein are due mainly to the endosperm whilein small grain, differences are due to the germ, particularlythe scutellum which is larger in op-2 kernels. Reserve proteincomposition was distinct: op-2 endosperms showed an increasein the proportions of albumins, globulins, and the glutelinG₃ fraction which was accompanied by a marked decrease in zeincontent in comparison with normal endosperms. During endosperm depletion there was a net increase in the salt-solublefraction prior to day 3 from imbibition; glutelins and zeinhowever decreased throughout, the former being degraded at initiallyfaster rates. In general, regardless of protein composition,the most abundant fraction was utilized most rapidly. Water uptake during imbibition was greater in op-2 grain, thoughno differences in axis growth in terms of dry weight or laminaarea were apparent at the end of reserve degradation. In bothnormal and op-2 seedlings, protein was mobilized both earlierand faster than endosperm dry matter and the shoot, principallythe first leaf lamina, received more reserve nitrogen than theroot.     

Assessing the nesting strategies of Late Cretaceous titanosaurs: 3‐D clutch geometry from a new megaloolithid eggsite

Vila, B., Galobart, À., Oms, O., Poza, B. & Bravo, A.M. 2009: Assessing the nesting strategies of Late Cretaceous titanosaurs: 3‐D clutch geometry from a new megaloolithid eggsite. Lethaia, Vol. 43, pp. 197–208. Detailed mapping and excavation at the egg locality of Font del Bullidor (Vallcebre Syncline, NE Iberian Peninsula) document various clutches with megaloolithid (Megaloolithus siruguei) eggs and provide significant information on the mode of incubation of Late Cretaceous titanosaurs. Clutches of eggs are preserved in a greyish lagoonal mudstone deposited overlying a sinuous channel infill. Despite the lithological uniformity of the mudstone, clutch architecture can be inferred from the topographical position of the eggs within some clutches. Mapping methods underscore the importance of documenting the spatial relationship of the egg‐bearing bed and the mapping plan, as well as an accurate 3‐D coordinate acquisition. Both geometry of the clutches and taphonomic observations on particular eggs indicate that eggs were laid in a shallow pit excavated into the substrate. Most of the eggs were incubated under a cover of sediment before hatching or cracking. This corroborates previous inferences on nesting mode. □Clutch, dinosaurs, eggs, Maastrichtian, Megaloolithus siruguei, Pyrenees.