Analysis of population structure and genetic diversity reveals gene flow and geographic patterns in cultivated rice (<Emphasis Type="Italic">O. sativa</Emphasis> and <Emphasis Type="Italic">O. glaberrima</Emphasis>) in West Africa

To fully exploit the diversity in African rice germplasm and to broaden the gene pool reliable information on the population genetic diversity and phenotypic characteristics is a prerequisite. In this paper, the population structure and genetic diversity of 42 cultivated African rice (Oryza spp.) accessions originating from West Africa (Benin, Mali and Nigeria, Liberia etc.) were investigated using 20 simple sequence repeats (SSR) and 77 amplified fragment length polymorphisms (AFLP). Additionally, field trials were set up to gain insight into phenotypic characteristics that differentiate the genetic populations among rice accessions. The analysis revealed considerably high polymorphisms for SSR markers (PIC mean?=?0.78) in the germplasm studied. A significant association was found between AFLP markers and geographic origin of rice accessions (R?=?0.72). Germplasm structure showed that Oryza sativa accessions were not totally isolated from Oryza glaberrima accessions. The results allowed identification of five O. glaberrima accessions which grouped together with O. sativa accessions, sharing common alleles of 18 loci out of the 20 SSR markers analyzed. Population structure analysis revealed existence of a gene flow between O. sativa and O. glaberrima rice accessions which can be used to combine several interesting traits in breeding programs. Further studies are needed to clarify the contributions of this gene flow to valuable traits such as abiotic and biotic stresses including disease resistance.     

6-Bromohypaphorine from Marine Nudibranch Mollusk Hermissenda crassicornis is an Agonist of Human α7 Nicotinic Acetylcholine Receptor

6-Bromohypaphorine (6-BHP) has been isolated from the marine sponges Pachymatisma johnstoni, Aplysina sp., and the tunicate Aplidium conicum, but data on its biological activity were not available. For the nudibranch mollusk Hermissenda crassicornis no endogenous compounds were known, and here we describe the isolation of 6-BHP from this mollusk and its effects on different nicotinic acetylcholine receptors (nAChR). Two-electrode voltage-clamp experiments on the chimeric α7 nAChR (built of chicken α7 ligand-binding and glycine receptor transmembrane domains) or on rat α4β2 nAChR expressed in Xenopus oocytes revealed no action of 6-BHP. However, in radioligand analysis, 6-BHP competed with radioiodinated α-bungarotoxin for binding to human α7 nAChR expressed in GH₄C₁ cells (IC₅₀ 23 ± 1 μM), but showed no competition on muscle-type nAChR from Torpedo californica. In Ca²⁺-imaging experiments on the human α7 nAChR expressed in the Neuro2a cells, 6-BHP in the presence of PNU120596 behaved as an agonist (EC₅₀ ~80 μM). To the best of our knowledge, 6-BHP is the first low-molecular weight compound from marine source which is an agonist of the nAChR subtype. This may have physiological importance because H. crassicornis, with its simple and tractable nervous system, is a convenient model system for studying the learning and memory processes.     

Post‐capture survival of whale sharks encircled in tuna purse‐seine nets: tagging and safe release methods

1. Whale shark, the world's largest fish, is believed to be particularly vulnerable owing to its biological characteristics (slow growth, late maturation, great longevity) and is listed as Vulnerable by IUCN and included in Appendix II of CITES. 2. Whale sharks are occasionally encircled in tropical tuna purse‐seine nets, throughout this global fishery. Although apparent immediate survival rates following encirclement and release have recently been assessed through scientific onboard observer programmes, a more rigorous methodology is still required for studying post‐released survival. 3. This work provides a method for applying pop‐up satellite tags and reports an enhanced release procedure for whale sharks. The first assessment of survival after release from purse‐seine nets involved six whale sharks tagged between May and September 2014 in the eastern tropical Atlantic Ocean. Five tags transmitted data: three popped up as programmed (after 30 days), while two surfaced prematurely (one after 21 and the other after 71 days (programmed to pop off after 30 and 90 days, respectively)) but showed no sign of unusual behaviour. 4. Overall, whale sharks survived at least 21 days (one at least 71 days) after release from purse‐seine nets. These observations based on five large individuals (total length > 8 m), suggest that whale sharks have a good chance of survival when released with the proposed method. 5. Additional tagging in this and other oceans, especially of juveniles which may be more sensitive to encirclement and release operations, is essential to further assess whale shark post‐release survival rates in tuna purse‐seine fisheries. Copyright © 2016 John Wiley & Sons, Ltd.     

Comparative study on the antioxidant and biological activities of carvacrol, thymol, and eugenol derivatives

Four derivatives of thymol, carvacrol, and eugenol were synthesized: 4-(hydroxymethyl)-5-isopropyl-2-methylphenol, 4,4'-methylenebis(5-isopropyl-2-methyl)phenol, 4-allyl-6-(hydroxymethyl)-2-methoxyphenol, and 4-(hydroxymethyl)-2-isopropyl-5-methylphenol. The obtained derivatives showed remarkably better antioxidative properties according to 1,1-diphenyl-2-picrylhydrazyl assay (50% inhibitory concentrations = 4-156 microg/mL) and Rancimat assay (protection factors = 1.55-5.84) when compared with parent compounds and values similar to or better than those of butylated hydroxytoluene and vitamin C. At concentrations of 10 mM carvacrol derivatives had no toxic effect on viability of Escherichia coli K-12 (determined by minimum inhibitory concentrations). Other phenol derivatives showed reduced cytotoxic effect on E. coli K-12 at concentrations of 2-5 mM on the basis of 50% lethal dose measurements. In comparison with the parent compounds, phenol derivatives showed reduced cytotoxic effect for Saccharomyces cerevisiae cells (determined by yeast colony reduction). On the other hand, the majority of synthesized compounds had dose-dependent antiproliferative effects on human uterine carcinoma cells (HeLa), which makes them potentially interesting for the adjuvant experimental cancer treatments. The 4,4'-methylenebis(5-isopropyl-2-methyl)phenol derivative of carvacrol showed lower inhibiting capacity also for the HeLa cells, which makes this particular derivative attractive as an efficient antioxidant with negligible cytotoxic effects.     

Forage intake and nitrogen metabolism of beef cattle grazing palisadegrass-calopo mixed pasture managed using canopy light interception

To define the best grazing management strategy, it is important to assess animals' responses to variations in the structure and composition of tropical forages. This 2-year study evaluated animal response to Marandu palisadegrass (Urochloa brizantha)-calopo (Calopogonium mucunoides) mixed pastures managed under rotational grazing. Treatments consisted of three defoliation frequencies defined by rest periods interrupted at 90% (90LI), 95% (95LI) and 100% (100LI) of photosynthetically active radiation interception (LI). The stubble post-grazing height target was 15 cm. Statistical difference was declared at p < .10. The 100LI had lowest crude protein (CP) and in vitro dry matter digestibility (IVDDM) for the Marandu palisadegrass (p = <.001 both) and calopo (p = .003 and p = .067, respectively). Also, the OM digestibility decreased 7.0% in the 100LI condition than 90LI and 95LI treatment (p = .005). There was no difference in forage, grass, and legume intakes between the treatments (p > .10). The 100LI treatment decreased CP intake from grass in 33.3% (p = <.001) compared to other treatments. Greatest production of microbial N (p = .093) occurred with the 90LI treatment. The CP/digestible organic matter (DOM) ratio, urinary N excretion and retained N were lowest in the 100LI treatment (p = <.001, p = .007 and p = .014, respectively). The recommendation for grazing between 90 and 95% of LI is recommended because of greater CP intake and N utilization for the animals and improved the nutritive value of Marandu palisadegrass and calopo mixed pastures.     

Accuracy of four ultrasonography techniques in predicting histopathological classification of canine mammary carcinomas

Due to the importance of presurgical, noninvasive, and accurate diagnostic tools in mammary carcinoma characterization, this prospective secondary observational cohort study was designed to evaluate and compare the diagnostic accuracy of B‐mode, Doppler, contrast enhancement ultrasonography, or acoustic radiation force impulse–elastography in identifying mammary carcinomas types with high degree of malignancy. A total of 246 mammary carcinomas from 141 female dogs were analyzed using B‐mode, Doppler, contrast enhancement ultrasonography, and acoustic radiation force impulse ultrasonography prior to their histopathological classification according to types (simple, complex, or special) and grade (I, II, or III). Qualitative and quantitative variables were compared between carcinoma types and grades by Fisher's or analysis of variance. Diagnostic performance was estimated by receiver‐operating characteristic analysis, using histopathological classification as a reference. Deformability (acoustic radiation force impulse) had a diagnostic specificity of 100% and sensitivity of 12% in identifying special carcinomas. A width:length ratio greater than 0.53 can be suggestive of special carcinoma, with 80% sensitivity and 76% specificity. Contrast wash‐in and peak enhancement times lower than 7.5 and 13.5 s, respectively, were indicative of complex carcinoma at 62% sensitivity and 60% specificity. Contrast wash‐in, peak enhancement, and wash‐out times greater than 6.5, 12.5, and 64.5 s, respectively; were indicative of grade II and III carcinoma at 68% sensitivity and 62% specificity. In conclusion, B‐mode ultrasonography, contrast enhancement ultrasonography, and acoustic radiation force impulse–elastography enabled the identification of some of the characteristics of high‐grade mammary carcinoma types and grades in female dogs with limited accuracy. The findings from this study may contribute to oncology research and clinical management canine patients.     

Soil Fertility,Sugarcane Yield Affected by Limestone,Silicate, and Gypsum Application

The aim of this study was to verify if the application of silicate or lime, in association with gypsum, on sugarcane residue can lead to amendment of subsurface soil acidity, increasing sugarcane yield and profitability. The treatments were: 1 – control (without application of amendments), 2 – gypsum, 3 – dolomitic limestone, 4 – silicate, 5 – dolomitic limestone + gypsum, and 6 – silicate + gypsum. The surface application of gypsum led to reduction in Al (aluminum) contents and Al saturation, and increase in Mg⁺², Ca⁺², K⁺, S–SO₄^?, and base saturation in deeper soil layers, as well as increased yield of stalks, sugar, trash, bagasse, and energy, and greater profit. The application of limestone and silicate, alone or in association with gypsum, amend soil acidity throughout the soil profile. It likewise leads to an increase in stalk, sugar, trash, bagasse, and energy yield, however, application of silicate in association with gypsum leads to the greatest profitability.     

Marine Natural Products Acting on the Acetylcholine-Binding Protein and Nicotinic Receptors: From Computer Modeling to Binding Studies and Electrophysiology

For a small library of natural products from marine sponges and ascidians, in silico docking to the Lymnaea stagnalis acetylcholine-binding protein (AChBP), a model for the ligand-binding domains of nicotinic acetylcholine receptors (nAChRs), was carried out and the possibility of complex formation was revealed. It was further experimentally confirmed via competition with radioiodinated α-bungarotoxin ([¹²⁵I]-αBgt) for binding to AChBP of the majority of analyzed compounds. Alkaloids pibocin, varacin and makaluvamines С and G had relatively high affinities (K_i 0.5–1.3 μM). With the muscle-type nAChR from Torpedo californica ray and human neuronal α7 nAChR, heterologously expressed in the GH₄C₁ cell line, no competition with [¹²⁵I]-αBgt was detected in four compounds, while the rest showed an inhibition. Makaluvamines (K_i ~ 1.5 μM) were the most active compounds, but only makaluvamine G and crambescidine 359 revealed a weak selectivity towards muscle-type nAChR. Rhizochalin, aglycone of rhizochalin, pibocin, makaluvamine G, monanchocidin, crambescidine 359 and aaptamine showed inhibitory activities in electrophysiology experiments on the mouse muscle and human α7 nAChRs, expressed in Xenopus laevis oocytes. Thus, our results confirm the utility of the modeling studies on AChBPs in a search for natural compounds with cholinergic activity and demonstrate the presence of the latter in the analyzed marine biological sources.