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81.
82.
Phoberomys is reported to be the largest rodent that ever existed, although it has been known only from isolated teeth and fragmentary postcranial bones. An exceptionally complete skeleton of Phoberomys pattersoni was discovered in a rich locality of fossil vertebrates in the Upper Miocene of Venezuela. Reliable body mass estimates yield approximately 700 kilograms, more than 10 times the mass of the largest living rodent, the capybara. With Phoberomys, Rodentia becomes one of the mammalian orders with the largest size range, second only to diprotodontian marsupials. Several postcranial features support an evolutionary relationship of Phoberomys with pakaranas from the South American rodent radiation. The associated fossil fauna is diverse and suggests that Phoberomys lived in marginal lagoons and wetlands. 相似文献
83.
Fang W Vega-Rodríguez J Ghosh AK Jacobs-Lorena M Kang A St Leger RJ 《Science (New York, N.Y.)》2011,331(6020):1074-1077
Metarhizium anisopliae infects mosquitoes through the cuticle and proliferates in the hemolymph. To allow M. anisopliae to combat malaria in mosquitoes with advanced malaria infections, we produced recombinant strains expressing molecules that target sporozoites as they travel through the hemolymph to the salivary glands. Eleven days after a Plasmodium-infected blood meal, mosquitoes were treated with M. anisopliae expressing salivary gland and midgut peptide 1 (SM1), which blocks attachment of sporozoites to salivary glands; a single-chain antibody that agglutinates sporozoites; or scorpine, which is an antimicrobial toxin. These reduced sporozoite counts by 71%, 85%, and 90%, respectively. M. anisopliae expressing scorpine and an [SM1](8):scorpine fusion protein reduced sporozoite counts by 98%, suggesting that Metarhizium-mediated inhibition of Plasmodium development could be a powerful weapon for combating malaria. 相似文献
84.
Letícia Z. Oliveira Vera F. M. Hossepian de Lima Marcelo A. Levenhagen Ricarda M. dos Santos Terezinha I. Assump??o José O. Jacomini André F. C. de Andrade Rubens P. de Arruda Marcelo E. Beletti 《Journal of veterinary science (Suw?n-si, Korea)》2011,12(3):267-272
The objective of this study was to characterize acrosomal ultrastructure following discontinuous Percoll gradient centrifugation of cryopreserved bovine sperm. Semen was collected from six bulls of different breeds and three ejaculates per bull were evaluated. Frozen semen samples were thawed and the acrosomal region of sperm cells was evaluated by transmission electron microscopy (TEM) before (n = 18) and after (n = 18) Percoll centrifugation. The evaluation of 20 sperm heads from each of the 36 samples analyzed ensured that a large number of cells were investigated. The data were subjected to analysis of variance at a level of significance of 5%. Percoll centrifugation reduced the percentage of sperm exhibiting normal acrosomes (from 61.77 to 30.24%), reduced the percentage of sperm presenting atypical acrosome reactions (from 28.38 to 4.84%) and increased the percentage of sperm exhibiting damage in the acrosome (from 6.14 to 64.26%). The percentage of sperm with typical acrosome reactions was not significantly different before (3.70%) and after (0.67%) centrifugation. TEM distinguished four different types of acrosomal status and enabled ultrastructural characterization of acrosomal injuries. The percentage of sperm exhibiting normal acrosomes decreased and damage in the acrosome was the most frequent acrosomal injury with the Percoll gradient centrifugation protocol utilized. 相似文献
85.
Carvalho RF Campos ML Pino LE Crestana SL Zsögön A Lima JE Benedito VA Peres LE 《Plant methods》2011,7(1):18-14
Background
The tomato (Solanum lycopersicum L.) plant is both an economically important food crop and an ideal dicot model to investigate various physiological phenomena not possible in Arabidopsis thaliana. Due to the great diversity of tomato cultivars used by the research community, it is often difficult to reliably compare phenotypes. The lack of tomato developmental mutants in a single genetic background prevents the stacking of mutations to facilitate analysis of double and multiple mutants, often required for elucidating developmental pathways.Results
We took advantage of the small size and rapid life cycle of the tomato cultivar Micro-Tom (MT) to create near-isogenic lines (NILs) by introgressing a suite of hormonal and photomorphogenetic mutations (altered sensitivity or endogenous levels of auxin, ethylene, abscisic acid, gibberellin, brassinosteroid, and light response) into this genetic background. To demonstrate the usefulness of this collection, we compared developmental traits between the produced NILs. All expected mutant phenotypes were expressed in the NILs. We also created NILs harboring the wild type alleles for dwarf, self-pruning and uniform fruit, which are mutations characteristic of MT. This amplified both the applications of the mutant collection presented here and of MT as a genetic model system.Conclusions
The community resource presented here is a useful toolkit for plant research, particularly for future studies in plant development, which will require the simultaneous observation of the effect of various hormones, signaling pathways and crosstalk. 相似文献86.
Elisabete Yurie Sataque Ono Elaine Cunha Moreno Mario Augusto Ono Carolina Nachi Rossi Gervásio Hitoshi Saito Édio Vizoni Yoshitsugu Sugiura Elisa Yoko Hirooka 《European journal of plant pathology / European Foundation for Plant Pathology》2011,131(4):653-660
In this study the effect of different cropping systems and crop successions was evaluated on natural Fusarium sp. contamination and fumonisin levels in corn. The cropping systems consisted of a conventional and no-tillage area cultivated
with corn in the summer following either oats or fallow in the winter (2006 and 2007 growing seasons). In addition, the effect
of applying nitrogen fertilizer (0, 22.5, 45.0, 90.0 and 90.0 kg ha−1 nitrogen supplemented with potassium oxide) on fumonisin contamination was evaluated in the 2006 growing season. Fusarium sp. was detected in 90% samples in 2006 and in 100% samples in 2007. In both growing seasons, no-till corn following oats
showed the highest mean fumonisin levels and differed significantly (P < 0.05) from all the others (2006) and from conventional till corn following either oats or fallow in the winter (2007).
Fumonisin levels ranged from 0.13 to 19.52 μg g−1 (mean 6.97 μg g−1) and from 3.70 to 7.75 μg g−1 (mean 6.29 μg g−1) in no-till corn following oats from the 2006 and 2007 growing seasons, respectively. Plots treated with 0 kg ha−1 and 22.5 kg ha−1 nitrogen showed the highest mean fumonisin levels and differed significantly from those with 45.0 and 90 kg ha−1 nitrogen. Fumonisin levels correlated negatively (P < 0.05) with the nitrogen fertilization rates. Although no-till is advantageous from a soil conservation standpoint, it may
enhance the potential for fumonisin contamination in corn. 相似文献
87.
Robson Thiago Xavier de Sousa Gaspar Henrique Korndörfer Rogério Augusto Brem Soares Patrícia Rezende Fontoura 《Journal of plant nutrition》2015,38(9):1444-1455
Phosphate applications are still rare in sugarcane cultivation and can be done with phosphorus fertilizers of residual over. This study aims to evaluate the agronomic efficiency of phosphate fertilization before sugarcane planting and its effect on sugarcane yield. The study was carried out over three crop cycles at the Jalles Machado sugar-mill in Goianésia, GO, Brazil. The treatments consisted of five different phosphorus sources (soluble and insoluble) applied at a rate of 300 kg ha?1 phosphorus pentoxide (P2O5). The phosphorus fertilizers used were: triple superphosphate, mono-ammonium phosphate (MAP), Arad rock phosphate, Itafós rock phosphate, and magnesium term phosphate. The effects of these fertilizers were evaluated by plant height (ground to Top Visible Dewlap; TVD), leaf phosphorus content, agronomic efficiency, and sugarcane yield from cane-plants, first ratoon, and second ratoon. Magnesium term phosphate and triple superphosphate resulted in greater plant-cane height. Leaf phosphorus concentrations were highest with applications of MAP, magnesium term phosphate, and triple superphosphate. Phosphate applications did not affect sugarcane plant yield, but did increase ratoon yield. In general, the residual effect of insoluble phosphate increased over the years. The agronomic efficiency (AE) of phosphate was (in descending order): triple superphosphate (100%), term phosphate (89%), MAP (80%), Itafós rock phosphate (67%), and Arad rock phosphate (60%). 相似文献
88.
Effects of water-soluble-fractions (WSFs) from No. 2 Fuel Oil on growth and reproduction in a laboratory strain of Neanthes arenaceodentata were studied in experiments simulating conditions of acute and chronic sublethal exposure. Effects were defined relative to concentrations of diaromatic hydrocarbons (naphthalenes) and total dissolved hydrocarbons. Hatching of metatrochophore larvae was inversely related to WSF concentration and to the length of time larvae were exposed prior to hatching. Growth of larvae into juveniles was unaffected by low concentrations. Inhibition of larval growth by higher WSF concentrations was reversible upon return of larvae to hydrocarbon-free sea water. Growth of juveniles into adult polychaetes was inversely related to concentration. Rate of development to the feeding juvenile stage was not affected by WSF in three successive generations of continuously exposed polychaetes. Oocyte maturation rates in the four WSF concentrations (2.5, 5, 10, 2507o) increased with each successive generation. All concentrations suppressed fecundity in each generation. Survival to the 32-segment juvenile stage (brood mortality) was inversely related to concentration in first generation animals. Brood mortality in all WSF concentrations decreased with successive generations thereafter. Levels of naphthalenes in worms declined with each generation. Naphthalenes concentrations in third generation animals was very similar to those of exposure media. 相似文献
89.
Ivaniele Nahas Duarte Robson Thiago Xavier de Sousa Gaspar Henrique Korndörfer Hamilton Seron Pereira 《Journal of plant nutrition》2015,38(12):1961-1972
Millet is a grass that responds to potassium fertilization and Alfa 01 and Alfa 02 are potential sources of this nutrient. Thus, the aim of this study was to evaluate the potential of as potassium sources by measuring accumulation of this nutrient in millet. The crop was grown in Ustoxic Quartzipsamment (RQo) soil. The experiment was set up in randomized blocks with three repetitions. The treatments consisting of three sources (KCl, Alfa 02, Alfa 01), two rates (200 and 400 kg ha?1 K2O) and with no K fertilization (control). Potassium chloride was used as the standard to which the other sources of potassium were compared. Two consecutive crops of millet were grown in the same pots. The first crop received potassium source application but not the second. At the end of experiment, shoot dry matter production, shoot potassium concentration, shoot accumulated potassium, soil potassium and relative agronomic efficiency were determined. The relative agronomic efficiency, calculated from crops, was 100% for KCl, was 84% for Alfa 02 and was 11% for Alfa 01. In the shoot dry matter production and accumulated potassium only Alfa 01 was not statistically different of control. Millet absorbed potassium from the Alfa 02 source in both the first and second crops. 相似文献
90.
Siani AC Tappin MR Ramos MF Mazzei JL Ramos MC De Aquino Neto FR Frighetto N 《Journal of agricultural and food chemistry》2002,50(12):3518-3521
A new chemotype of the aromatic Verbenaceae species Lippia alba Mill. N. E. Br. from southeastern Brazil has recently been shown to have a high content of linalool in the leaf essential oil. Vegetative propagation of this chemotype was conducted at six different locations in Brazil, and the variation of the content and the optical purity of linalool in the oils were verified. Yields (0.6-0.9%, hydrodistillation), chemical composition, linalool content, and optical purity of the oils from all the plants were compared, using GC-FID, GC-MS, chiral chromatography, and retention index calculation. No plant exceeded the matrix in linalool content (46.5 to 90.7%), and the chemical profile of the oils was the same for all the samples. Purification of linalool to a content close to 100% was effected by vacuum distillation of the crude oil. Chiral analysis showed exclusively the presence of S-linalool in all the crude oils and in the distilled samples. 相似文献