Conformations of peptides containing Z-alpha,beta-dehydroleucine (delta ZLeu). A comparison of Boc-Pro-delta ZLeu-Gly-NHEt and Boc-Pro-delta ZPhe-Gly-NHEt.

Two tripeptides of the type Boc-Pro-ΔZX-Gly-NHEt (where X = Leu, Phe) have been synthesized and their solution conformations investigated by 270 MHz 1H n.m.r. and i.r. spectroscopy. These conformational studies indicated that ΔZLeu, similar to ΔZPhe, has a strong tendency to stabilize folded Type II β-turn conformations when present at i + 2 position.

Acid-Catalyzed Thermal Rearrangement of Gamm,Delta-Unsaturated Ketones

Thermal activation of gamma,delta-unsaturated ketones (1, 9 and 12) in the presence of a catalytic amount of propionic acid causes a rearrangement to give new gamma,delta-unsaturated ketones (2, 10 and 14) via an intramolecular ene reaction followed by a retro-ene reaction.

Crystal structure of Boc-LAla-Delta Phe-Delta Phe-Delta Phe-Delta Phe-NHMe: a left-handed helical peptide

alpha,beta-Dehydrophenylalanine residues constrain the peptide backbone to beta-bend conformation. A pentapeptide containing four consecutive (Delta Phe) residues has been synthesised and crystallised. The peptide Boc-LAla-Delta Phe-Delta Phe-Delta Phe-Delta Phe-NHMe (C45H46N6O7, MW = 782.86) was crystallised from an acetonitrile/methanol mixture. The crystal belongs to the orthorhombic space group P2(1)2(1)2(1) With a = 19.455(6), b = 20.912(9), c = 11.455(4) Angstrom and Z = 4. The X-ray (MoKalpha, lambda = 0.7107 Angstrom) intensity data were collected using the Rigaku-AFC7 diffractrometer. The crystal structure was determined by direct methods and refined using the least-squares technique, R = 8.41% for 1827 reflections with \F-o\ > 4 sigma\F-o\. The molecule contains the largest stretch of consecutive dehydrophenylalanine residues whose crystal structure has been determined so far. The peptide adopts left-handed 3(10)-helical conformation despite the presence of LAla at the N-terminus. The mean phi, psi values, averaged across the last four residues are 56.8 degrees and 17.5 degrees, respectively. There are four 4-->1 intramolecular hydrogen bonds, characteristic of the 3(10)-helix. In the crystal each molecule interacts with four crystallographically symmetric molecules with one hydrogen bond each.

Thermodynamic properties of LaFeO3-delta and LaFe12O19

The standard Gibbs energies of formation of lanthanum orthoferrite (LaFeO3-delta) and hexaferrite (LaFe12O19)were determined using solid-state electrochemical cells incorporating yttria-stabilized zirconia as the electrolyte and pure oxygen gas at ambient pressure as the reference electrode. From emf of the solid-state cell, the Gibbs energy of formation of nonstoichiometric orthoferrite (LaFeO3-delta) is obtained. To derive values for the stoichiometric phase, variation of the oxygen nonstoichiometric parameter with oxygen partial pressure was measured using thermogravimetry under controlled gas mixtures. The results obtained for LaFeO3 and LaFe12O19 can be summarized by the following equations, which represent the formation of ternary oxides from their component binary oxides: 1/2 La2O3 + 1/2 Fe2O3 -> LaFeO3: Delta G degrees (LaFeO3) (+/- 450) (J mol(-1)) = -62920 - 2.12T (K), and 1/2 La2O3 + 9/2Fe(2)O(3) + Fe3O4 -> LaFe12O19; Delta G degrees (LaFe12O19) (+/- 200) (J mol(-1)) = -103900 + 21.25T (K). These data are discussed critically in comparison with thermodynamic values reported in the literature from a variety of measurements. The values obtained in this study are consistent with calorimetric entropy and enthalpy of formation of the perovskite phase and with some of the Gibbs energy measurements reported in the literature. For the lanthanum hexaferrite (LaFe12O19) there are no prior thermodynamic measurements for comparison. (c) 2011 Elsevier B.V. All rights reserved.

Denaturant mediated unfolding of both native and molten globule states of maltose binding protein are accompanied by large [Delta]Cp's

Maltose binding protein (MBP) is a large, monomeric two domain protein containing 370 amino acids. In the absence of denaturant at neutral pH, the protein is in the native state, while at pH 3.0 it forms a molten globule. The molten globule lacks a tertiary circular dichroism signal but has secondary structure similar to that of the native state. The molten globule binds 8-anilino-1-naphthalene sulfonate (ANS). The unfolding thermodynamics of MBP at both pHs were measured by carrying out a series of isothermal urea melts at temperatures ranging from 274–329 K. At 298 K, values of [Delta]G°, [Delta]Cp, and Cm were 3.1 ± 0.2 kcal mol−1, 5.9 ± 0.8 kcal mol−1 K−1 (15.9 cal (mol-residue)−1 K−1), and 0.8 M, respectively, at pH 3.0 and 14.5 ± 0.4 kcal mol−1, 8.3 ± 0.7 kcal mol−1 K−1 (22.4 kcal (mol-residue)−1 K−1), and 3.3 M, respectively, at pH 7.1. Guanidine hydrochloride denaturation at pH 7.1 gave values of [Delta]G° and [Delta]Cp similar to those obtained with urea. The m values for denaturation are strongly temperature dependent, in contrast to what has been previously observed for small globular proteins. The value of [Delta]Cp per mol-residue for the molten globule is comparable to corresponding values of [Delta]Cp for the unfolding of typical globular proteins and suggests that it is a highly ordered structure, unlike molten globules of many small proteins. The value of [Delta]Cp per mol-residue for the unfolding of the native state is among the highest currently known for any protein.

Impact of heavy metals on bacterial communities from mangrove soils of the Mahanadi Delta (India)

This study aimed to assess soil nutrient status and heavy metal content and their impact on the predominant soil bacterial communities of mangroves of the Mahanadi Delta. Mangrove soil of the Mahanadi Delta is slightly acidic and the levels of soil nutrients such as carbon, nitrogen, phosphorous and potash vary with season and site. The seasonal average concentrations (g/g) of various heavy metals were in the range: 14810-63370 (Fe), 2.8-32.6 (Cu), 13.4-55.7 (Ni), 1.8-7.9 (Cd), 16.6-54.7 (Pb), 24.4-132.5 (Zn) and 13.3-48.2 (Co). Among the different heavy metals analysed, Co, Cu and Cd were above their permissible limits, as prescribed by Indian Standards (Co=17g/g, Cu=30 g/g, Cd=3-6 g/g), indicating pollution in the mangrove soil. A viable plate count revealed the presence of different groups of bacteria in the mangrove soil, i.e. heterotrophs, free-living N-2 fixers, nitrifyers, denitrifyers, phosphate solubilisers, cellulose degraders and sulfur oxidisers. Principal component analysis performed using multivariate statistical methods showed a positive relationship between soil nutrients and microbial load. Whereas metal content such as Cu, Co and Ni showed a negative impact on some of the studied soil bacteria.

Diurnal and seasonal variation of mixing ratio and delta C-13 of air CO2 observed at an urban station Bangalore, India

We present here observations on diurnal and seasonal variation of mixing ratio and delta C-13 of air CO2, from an urban station-Bangalore (BLR), India, monitored between October 2008 and December 2011. On a diurnal scale, higher mixing ratio with depleted delta C-13 of air CO2 was found for the samples collected during early morning compared to the samples collected during late afternoon. On a seasonal scale, mixing ratio was found to be higher for dry summer months (April-May) and lower for southwest monsoon months (June-July). The maximum enrichment in delta C-13 of air CO2 (-8.04 +/- 0.02aEuro degrees) was seen in October, then delta C-13 started depleting and maximum depletion (-9.31 +/- 0.07aEuro degrees) was observed during dry summer months. Immediately after that an increasing trend in delta C-13 was monitored coincidental with the advancement of southwest monsoon months and maximum enrichment was seen again in October. Although a similar pattern in seasonal variation was observed for the three consecutive years, the dry summer months of 2011 captured distinctly lower amplitude in both the mixing ratio and delta C-13 of air CO2 compared to the dry summer months of 2009 and 2010. This was explained with reduced biomass burning and increased productivity associated with prominent La Nina condition. While compared with the observations from the nearest coastal and open ocean stations-Cabo de Rama (CRI) and Seychelles (SEY), BLR being located within an urban region captured higher amplitude of seasonal variation. The average delta C-13 value of the end member source CO2 was identified based on both diurnal and seasonal scale variation. The delta C-13 value of source CO2 (-24.9 +/- 3aEuro degrees) determined based on diurnal variation was found to differ drastically from the source value (-14.6 +/- 0.7aEuro degrees) identified based on seasonal scale variation. The source CO2 identified based on diurnal variation incorporated both early morning and late afternoon sample; whereas, the source CO2 identified based on seasonal variation included only afternoon samples. Thus, it is evident from the study that sampling timing is one of the important factors while characterizing the composition of end member source CO2 for a particular station. The difference in delta C-13 value of source CO2 obtained based on both diurnal and seasonal variation might be due to possible contribution from cement industry along with fossil fuel / biomass burning as predominant sources for the station along with differential meteorological conditions prevailed.

Influence of the upwelling events on the delta C-13 and delta O-18 of the benthic bivalve shells of the South Western Continental Margin of India

In this study, the influence of the spatial and temporal variability of upwelling intensity and the associated biological productivity observed during different phases of summer monsoon along the southwestern continental margin of India (SWCMI) on the delta C-13 and delta O-18 of the inorganic biogenic carbonate shells was investigated. Multispecies benthic bivalve shells (1-5 mm) separated from ten surface sediment samples of SWCMI (off 12 degrees N, 10 degrees N and 9 degrees N) collected during the onset (OSM) and peak (PSM) phase of the summer monsoon of 2009 were analysed for delta C-13 and delta O-18. Sea surface temperature along the study region indicates prominent upwelling in PSM than in OSM. A comparison of analytical and predicted values for delta O-18 in the bivalve shells confirmed their in situ origin during both the sampling periods. During PSM, the delta C-13 values in the benthic bivalve shells were more depleted in C-13 than during OSM which recorded lower values of delta C-13 in dissolved inorganic carbon of bottom waters expected in the study region in PSM due to the upwelled waters, high surface productivity and the associated high degradation of the organic matter in the subsurface and bottom waters. However, this depletion of delta C-13 was not observed in benthic bivalve shells obtained from 10 degrees N, since it is influenced by high export fluxes of carbon from the Cochin estuary since early monsoon months.

The incidence of Nypa fruticans (Wurmb) and its impact on fisheries production in the Niger Delta mangrove ecosystem

Nypa fruticans occurs in Bayelsa, Rivers, Akwa Ibom and Cross River State, Nigeria; invading an estimated area of 821 Km super(2) mangrove dominated swamps. Human activities such as tree felling, urbanization, oil and gas exploration and exploitation and other activities led to the interference in the normal mangrove by the Nypa palm. Lack of utilization by the local population of the Nypa palm as in into-pacification has increased the population over the years. The effect includes the reduction in primary and secondary productivity, disruption of food chain and erosion of riverbanks. The eradication of the Nypa palm from the Niger delta mangrove ecosystem and replacement with red and white mangroves will restore the ecosystem health and enhance biological diversity

Sustainability of indigenous technology in postharvest fisheries operations in Edo and Delta states, Nigeria

The study examined the sustainability of various indigenous technologies in post-harvest fishery operation in Edo and Delta States (Nigeria). A total of seventy processors were interviewed during the survey through a random selection. The data obtained were analysed by descriptive statistics. The results obtained revealed that the majority of the fish processors within the study areas were married with women who were not educated beyond the first Leaving School Certificate. Most of the fish processed were bought fresh, while the commonest method of preservation/processing practiced was smoking. The type of processing equipment used was the Chorkor smoking kiln and the drum smoker while the commonest source of energy is firewood. The processing activities within the communities were found to be profitable. However it was observed that due to the high cost of processing materials and equipment, the economic growth and the living standard is quite low. Some recommendations were made to improve the traditional method of fish preservation and processing

Observations on the ecology of Hepsetus odoe, Bloch, 1794 (Pisces: Hepsetidae) in Epie Creek floodplain, Niger Delta, Nigeria

The distribution, abundance, age and growth, the food and feeding habits, condition factor and reproduction of Hepsetus odoe in the Epie Creek Floodplain (Nigeria) was studied. H. odoe occur in the creek, swamp channel and lake. It is a very common, abundant and one of the major commercial species. A total of 457 specimens weighing 76.90 kg were caught during the period of investigation. The catches were more abundant in the dry season than in the wet season. The total length ranged from 10 cm to 46 cm while the weight varied between 50 g and 900 g. Six distinct components or year classes were observed using Bhattacharya's method. A growth exponential value 'b' was 3.35 with condition factor, 'k' values ranging from 0.69 to 0.83. The main diets of Hepsetus odoe were fish, including crustaceans (shrimps) and insects. The mean fecundity was 6060 plus or minus 358 eggs (range 2,769 to 6.667 eggs). The ova diameter of H. odoe was found to range from 2.2 mm to 2.6 mm with overall mean = 2.4 plus or minus 0.1)

On holism, reductionism and working from 9 to 5

A discussion is presented on the 2 approaches - holism and reductionism - in the study of environmental sciences, making reference to various projects presently being conducted by ICLARM and its collaborators using the holistic approach. Schematic representations are given of ICLARM's FISHBASE, the ECOPATH II model of the Peruvian upwelling ecosystem and submodels which may be incorporated in large simulation models of the upwelling system, and also material flows in a rice-fish/shrimp integrated farming systems of the Mekong Delta, Vietnam.

Impact of sedimentalogical processes on mangrove ecosystem of the Indus Delta

A detailed sedimentalogical study concerning the depletion of mangrove in the Indus Delta due to the marked decrease in the supply of silt was undertaken. Thirty one stations were established for sampling in a selected area of 12000 hectares between Korangi creek and Wad do Khuddi creek. Seventy one samples of soil were collected from 6cm and 1m depth, out of which fifty one samples were selected for sedimentalogical studies. It was inferred from this study that the marine depositional processes are distinctly dominating over the fluvial processes, which is major cause in decreasing the growth of mangrove. It was also inferred that among the sampled stations the sites having clayey silt (with silt 60%-70% and clay 25%-30%) are most favourable for mangrove plantation.