Seismotectonics of mid-ocean ridge propagation in Hess Deep     

Floyd JS  Tolstoy M  Mutter JC  Scholz CH 《Science (New York, N.Y.)》2002,298(5599):1765-1768

Hydroacoustic data from the eastern equatorial Pacific reveal low-magnitude seismicity concentrated at the propagating tip of the Galapagos Rise in Hess Deep. The patterns of seismicity and faulting are similar to those observed in the process zone of laboratory-scale propagating tensile cracks. Because the fracture energy required for propagation scales with crack length and process zone size, it follows that ridges can propagate stably in the brittle crust without exceptional resisting forces as proposed by previous models based on linear elastic fracture mechanics.  相似文献   

Association of staygreen trait with canopy temperature depression and yield traits under terminal heat stress in wheat (Triticum aestivum L.)     

Maya Kumari  R. N. Pudake  V. P. Singh  Arun K. Joshi 《Euphytica》2013,190(1):87-97

The presence or absence of the staygreen trait was screened for 3 consecutive years in 963 wheat lines from various sources, including Indian and CIMMYT germplasm. Staygreen was assessed at the late dough stage by visual scoring (0–9 scale) and the leaf area under greenness (LAUG) measurement. Around 5.5 % of the lines were staygreen, 10.5 % were moderately staygreen, and the remaining lines showed little or no expression of the trait. One hundred lines showing diversity for the staygreen trait were sown under three different sowing dates (timely, late and very late) for 3 consecutive years in three replications to determine the association of staygreen with heat tolerance. There was a decline in yield, biomass, grain filling duration (GFD) and 1,000 grain weight (TGW) under late and very late sowing conditions owing to terminal stress at anthesis and later stages. However, the decline was relatively less in staygreen genotypes compared to the non-staygreen (NSG) ones. The correlation study showed that LAUG and canopy temperature depression (CTD) were strongly correlated. LAUG and CTD were also significantly associated with grain yield, GFD and biomass. To further confirm the association of the staygreen trait with terminal heat stress, individual F₂-derived F₇ progenies from the cross of the ‘staygreen’ lines with NSG were evaluated for yield and yield traits at the three sowing dates. In each cross, the staygreen progenies showed a significantly smaller decline in yield and TGW under heat stress than the NSG progenies. These results appear to suggest an association between the staygreen trait and terminal heat stress and, thereby, that the staygreen trait could be used as a morphological marker in wheat to screen for heat tolerance.  相似文献   

Sexing of Dog Sperm by Fluorescence In Situ Hybridization     

Maya OI  Keisuke YAMADA  Hiroyuki HAYAKAWA  Hiroshi SUZUKI 《The Journal of reproduction and development》2013,59(1):92-96

Effective preselection of sex has been accomplished in several species of livestock and also in humans using the flow cytometric sperm sorting method. A guaranteed high sorting accuracy is a key prerequisite for the widespread use of sperm sexing. The standard validation method is flow cytometric remeasurement of the DNA content of the sexed sperm. Since this method relies on the same instrument that produced the original sperm separation, it is not truly independent. Therefore, to be able to specifically produce either male or female offspring in the dog, we developed a method of direct visualization of sex chromosomes in a single sperm using fluorescence in situ hybridization (FISH) as a validation method. Denaturation of canine spermatozoa by immersion in 1 M NaOH for 4 min yielded consistent hybridization results with over 97% hybridization efficiency and a good preservation of sperm morphology. There was no significant difference between the theoretical ratio (50:50) and the observed ratio of X- and Y-chromosome-bearing spermatozoa in any of the three dogs. In addition, the mean purities of flow-sorted sex chromosomes in spermatozoa of the three dogs were 90.8% for the X chromosome fraction and 89.6% for the Y chromosome fraction. This sorting was evaluated by using the dual color FISH protocol. Therefore, our results demonstrated that the FISH protocol worked reliably for both unsorted and sexed sperm samples.  相似文献   

Physiochemical and Textural Alterations in Indian Squid (Loligo duvauceli) Mantle During Frozen Storage and Cooking     

Maya Raman 《Journal Of Aquatic Food Product Technology》2013,22(5):454-467

Textural variations in squid mantle and the role of proteins on texture during frozen storage and cooking were investigated. Myofibrillar protein (62.36%) and pepsin soluble collagen (10.70%) accounted for the major fraction of total protein (22.17%). The histochemistry of mantle tissue showed a mesh-like arrangement of myofibrillar proteins with a collagenous dermal layer and feebly passing collagen through myotome bundles. Texture profile analysis of unfrozen mantle suggested the first phase of hardening at 50°C with hardness 1 (H1) of 11.53 kgf and hardness 2 (H2) of 9.68 kgf; and the second phase of hardening with optimal texture and maximum juiciness at 70°C (H1, 8.11 kgf; H2, 7.13 kgf) that varied with extended frozen storage. Increased frozen storage and cooking led to protein denaturation and formation of new low molecular weight proteins as evidenced in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE); these possibly influenced the functional and microstructural properties of the tissue.  相似文献   

Diversity of woody plant seedling banks under closed canopy in fragmented coppice forests     

Maya Gonzalez  Marc Deconchat  Gérard Balent  Alain Cabanettes 《Annals of Forest Science》2008,65(5):511-511

? Seedling banks of woody species established under closed canopy have received little consideration in coppice forests despite their potential importance for natural regeneration.

? This study aimed to evaluate the influences of canopy composition and of distance from the nearest forest edge on the abundance and species richness of the seedling bank, for different ecological groups of seedlings (age, successional status and dispersal vector) in 68 fragmented coppice stands.

? Seedlings were found in 67 stands, with 19 species identified. Eight species present as older seedlings were lacking as first-year old seedlings, suggesting temporal variability of species recruitment. Seedling abundances of species with low-dispersal ability were positively correlated with the abundances of their conspecific adults. Seedling abundance of mid-successional species was negatively correlated with the distance from the nearest forest edge, while mid-to-late successional species seedling abundance presented the opposite pattern.

? Our results showed that woody species were able to establish frequently under closed canopy in these fragmented coppices and form a seedling bank which may be used for natural regeneration.

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Epigenetic regulation – contribution to herbicide resistance in weeds?          下载免费PDF全文

Catarine Markus  Ratna Karan  Jacob N Barney  Aldo Merotto Jr 《Pest management science》2018,74(2):275-281

Continuous use of herbicides has resulted in the evolution of resistance to all major herbicide modes of action worldwide. Besides the well‐documented cases of newly acquired resistance through genetic changes, epigenetic regulation may also contribute to herbicide resistance in weeds. Epigenetics involves processes that modify the expression of specific genetic elements without changes in the DNA sequence, and play an important role in re‐programming gene expression. Epigenetic modifications can be induced spontaneously, genetically or environmentally. Stress‐induced epigenetic changes are normally reverted soon after stress exposure, although in specific cases they can also be carried over multiple generations, thereby having a selective benefit. Here, we provide an overview of the basis of epigenetic regulation in plants and discuss the possible effect of epigenetic changes on herbicide resistance. The understanding of these epigenetic changes would add a new perspective to our knowledge of environmental and management stresses and their effects on the evolution of herbicide resistance in weeds. © 2017 Society of Chemical Industry  相似文献   

Arsenic Bioaccumulation by <Emphasis Type="Italic">Eruca sativa</Emphasis> Is Unaffected by Intercropping or Plant Density     

Maya Lim  Murray B. McBride  André Kessler 《Water, air, and soil pollution》2017,228(9):364

Because crop uptake of arsenic from soils poses a human health concern, this study examines the effect of plant species, neighborhood, and planting density on arsenic uptake by brassicas grown with companion crops. At a field site contaminated by arsenic and lead, we measured arsenic uptake in arugula (Eruca sativa) and collards (Brassica oleracea var. acephala) grown in arrangements varying in species diversity and density. We further tested the effect of species diversity on arsenic uptake in two greenhouse experiments with arsenic-spiked potting soil, one test using brassicaceous plants with intercropped pairs of arugula, collards, and kale (B. oleracea var. acephala). The other had intercropped pairs of arugula, lettuce (Lactuca sativa), and marigold (Tagetes patula). Arugula in all cropping arrangements accumulated the highest and most variable concentrations of arsenic compared to other species, with neither species diversity in the companion crops nor planting density affecting arsenic uptake. We observed increased phosphorus and sulfur uptake by arugula exposed to soil arsenic in the greenhouse brassica intercropping experiments, a result that may be explained by a biological response to arsenic or competition of arsenate with phosphate and sulfate for adsorption sites in the soil. Arsenic uptake was largely independent of plant-plant facilitation effects sometimes reported for other elements, possibly because of strong buffering of the bioavailable fraction of arsenic in the soils tested.  相似文献   

Saccate thallus of the red alga Halosaccion glandiforme harbor diverse invertebrate fauna     

Bhaduri  Ritindra N.  Wolf  Maya 《International Aquatic Research》2017,9(2):169-176

International Aquatic Research - Rocky intertidal zones are biologically diverse environments with numerous physical stressors; as such, close associations between organisms often develop to...  相似文献   

Depth distribution of aluminum and heavy metals in soils of Costa Rican coffee cultivation areas     

Wolfgang Wilcke  Sigrid Kretzschmar  Maya Bundt  Guillermo Saborío  Wolfgang Zech 《植物养料与土壤学杂志》2000,163(5):499-502

Depth distributions of metals in soil profiles are indicative of weathering and soil genesis and anthropogenic pollution. We studied the depth distribution of total Al, Cd, Cu, Fe, Mn, Pb, and Zn concentrations in 8 Oxisols, 5 Andisols, 2 Mollisols, and 2 Alfisols of coffee plantation areas in Costa Rica. The concentrations of the mainly geo‐/pedogenic Al (means of 76 g kg^—1 in the A horizons and of 106 g kg^—1 in the lowermost sampled B horizons) and Fe (A: 56 g kg^—1, B: 66 g kg^—1) generally increased with profile depth. In spite of the regular application of Cu‐containing fungicides, Cu (A: 135 mg kg^—1, B: 158 mg kg^—1) showed accumulations in the A horizons of only three profiles. Higher Cd (A: 0.14 mg kg^—1, B: 0.09 mg kg^—1) and Pb concentrations (A: 7.3 mg kg^—1, B: 5.5 mg kg^—1) in most topsoils compared to the subsoils indicated anthropogenic inputs. The mean Mn (A: 1190 mg kg^—1, B: 1150 mg kg^—1) and Zn (A: 59 mg kg^—1, B: 66 mg kg^—1) concentrations varied little with depth. In general, the metal depth distribution in the studied tropical soils was similar to that of temperate soils although the weathering regime is quite different.  相似文献   

Metabolism of some sterol inhibitors in fungi and higher plants,with special reference to the selectivity of fungicidal action     

Maya Gasztonyi  Gyula Josepovits 《Pest management science》1984,15(1):48-55

The metabolism of triforine, chloraniformethan, the α-(pyrimidin-5-yl)benzhydryl alcohols (fenarimol, nuarimol and triarimol), the trityl-azoles (fluotrimazole and clotrimazole), and the morpholine types of sterol inhibitors is reviewed; the metabolism of the azolyl-alkane derivatives (mainly triadimefon and triadimenol) is discussed in detail. Redox and hydrolytic reactions are of primary importance. Enzymic inactivation may be one factor influencing fungicide selectivity. Metabolism is the dominant factor of selectivity if it represents the activation process, as with triadimefon. Transformations in higher plants do not differ significantly from those occurring in fungi, except that factors such as the formation of conjugates with natural compounds of plant tissues also play a role, as with triforine and triadimenol. The selectivity of fungitoxic action may be influenced by metabolism both in the host plant and the pathogen.  相似文献