Role of Light and Malate in the Decreased Sensitivity of cms-T Cytoplasm Maize Leaves to Bipolaris maydis Race T Toxin     

Garraway MO  Park DS  Beltran JD 《Phytopathology》1998,88(6):556-562

ABSTRACT Leaf segments from Texas male sterile (cms-T) cytoplasm maize isolines exposed to light (50 muM s(-1) m(-2)) for 8 h or more before or after being infiltrated with the Bipolaris maydis race T toxin (T-toxin) leaked significantly less electrolytes when immersed in distilled water (DW) for 24 to 48 h than did dark-treated leaf segments. No comparable effect of light on toxin-induced electrolyte leakage was observed with normal (N) cytoplasm isolines. Toxin-treated cms-T leaf segments incubated in DW for three consecutive 12-h periods of alternating light and dark showed significantly greater electrolyte leakage than leaf segments incubated in continuous light for 36 h and significantly less leakage than segments incubated in continuous dark for 36 h.Exposure of cms-T, but not N, cytoplasm leaves to 25 or 50 muM malic acid decreased their sensitivity to T-toxin in the dark to a level similar to that observed when leaves were incubated in the light without malic acid. The potency of T-toxin appeared to be unaffected by its exposure to light. The loss of electrolytes from T-toxin-treated cms-T cytoplasm leaf segments was at approximately the level seen with light or malate when 25 muM H(2)O(2) was added to the DW bathing solution. Evaluation of the data points to the possibility that H(2)O(2) might be involved with the altered sensitivity of cms-T cytoplasm leaves to T-toxin caused by either light or malate.  相似文献   

Factors influencing fallback by adult Atlantic salmon following transport into a novel river reach     

Danielle M. Frechette  Elsa Goerig  Normand E. Bergeron 《Fisheries Management and Ecology》2020,27(1):20-31

Transport of salmonids allows upstream migrating adults to bypass barriers to migration, for example hydroelectric dams or adverse habitats. Downstream movement (“fallback”) after transport is common and removes individuals from spawning populations, with possible detrimental consequences for population productivity. Time‐to‐event analysis was used to determine effects of fish characteristics, transport conditions and environmental variables on fallback by adult Atlantic salmon transported to an inaccessible river reach as a population enhancement strategy on the Rivière Sainte‐Marguerite Nord‐Est (Québec, Canada). Of 68 salmon transported, 19 exhibited post‐transport fallback within seven days of transport. Fork length (FL) was the only factor that increased risk of post‐transport fallback; there was a 5% increase in the proportion of large salmon (≥780 mm FL) exhibiting post‐transport fallback relative to individuals of median size (750 mm FL). Although the present study was limited by small sample size, the findings will help inform design of transport programmes in freshwater systems.  相似文献   

Production and isolation of aflatoxin M1 for toxicological studies     

D P Hsieh  L M Beltran  M Y Fukayama  D W Rice  J J Wong 《Journal of the Association of Official Analytical Chemists》1986,69(3):510-512

One hundred mg aflatoxin M1 was produced and purified for toxicological studies. Aspergillus flavus NRRL 3251 was cultured on rice to produce aflatoxins B1, B2, M1, and M2, B1 and B2 were separated from M1 and M2 by a normal phase low pressure liquid chromatography (LC) column. M1 was then separated from M2 by a reverse phase low pressure LC column. Recoveries of aflatoxins from the LC columns were about 90%. The purified M1 was confirmed by ultraviolet-visible spectrometry, mass spectrometry, nuclear magnetic resonance spectrometry, optical rotation, and its mutagenicity to Salmonella typhimurium TA98.  相似文献   

Landscape Conservation Cooperatives: Building a Network to Help Fulfill Public Trust Obligations     

Cynthia A. Jacobson  Elsa M. Haubold 《Human Dimensions of Wildlife》2014,19(5):427-436

The Landscape Conservation Cooperative (LCC) network (Network), comprised of 22 conservation partnerships spanning North America and U.S. Islands, is uniquely positioned to assist government members in fulfilling their public trust obligations to sustain natural and cultural resources for current and future generations by (a) ensuring inclusivity of broad stakeholder participation in conservation decision-making, and (b) building capacity for public trust to work in conservation, thus increasing the chance for successful and lasting conservation outcomes. In this article, we discuss the vision for the Network; challenges individual LCCs and the Network face in achieving the vision of sustaining natural and cultural resources for the benefit of current and future generations, a public trust obligation of most of the members; and ways in which member LCCs are making progress in this regard. We offer recommendations for the Network to consider to improve its ability to meet public trust obligations.  相似文献   

Productivity is a poor predictor of plant species richness   总被引：5，自引：0，他引：5  

Adler PB  Seabloom EW  Borer ET  Hillebrand H  Hautier Y  Hector A  Harpole WS  O'Halloran LR  Grace JB  Anderson TM  Bakker JD  Biederman LA  Brown CS  Buckley YM  Calabrese LB  Chu CJ  Cleland EE  Collins SL  Cottingham KL  Crawley MJ  Damschen EI  Davies KF  DeCrappeo NM  Fay PA  Firn J  Frater P  Gasarch EI  Gruner DS  Hagenah N  Hille Ris Lambers J  Humphries H  Jin VL  Kay AD  Kirkman KP  Klein JA  Knops JM  La Pierre KJ  Lambrinos JG  Li W  MacDougall AS  McCulley RL  Melbourne BA  Mitchell CE  Moore JL  Morgan JW  Mortensen B 《Science (New York, N.Y.)》2011,333(6050):1750-1753

For more than 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating local diversity. The original view, which is still widely accepted, holds that the relationship is hump-shaped, with richness first rising and then declining with increasing productivity. Although recent meta-analyses questioned the generality of hump-shaped patterns, these syntheses have been criticized for failing to account for methodological differences among studies. We addressed such concerns by conducting standardized sampling in 48 herbaceous-dominated plant communities on five continents. We found no clear relationship between productivity and fine-scale (meters(-2)) richness within sites, within regions, or across the globe. Ecologists should focus on fresh, mechanistic approaches to understanding the multivariate links between productivity and richness.  相似文献   

Influence of the timing of nitrogen additions during synthetic grape must fermentations on fermentation kinetics and nitrogen consumption   总被引：2，自引：0，他引：2  

Beltran G  Esteve-Zarzoso B  Rozès N  Mas A  Guillamón JM 《Journal of agricultural and food chemistry》2005,53(4):996-1002

Nitrogen deficiencies in grape musts are one of the main causes of stuck or sluggish wine fermentations. In the present study, we have supplemented nitrogen-deficient fermentations with a mixture of ammonium and amino acids at various stages throughout the alcoholic fermentation. The timing of the nitrogen additions influenced the biomass yield, the fermentation performance, the patterns of ammonium and amino acid consumption, and the production of secondary metabolites. These nitrogen additions induced a nitrogen-repressed situation in the cells, and this situation determined which nitrogen sources were selected. Glutamine and tryptophan were the main amino acids consumed in all the fermentations. Ammonium is the preferred nitrogen source for biomass production but was hardly consumed when it was added in the final stages of the fermentation. The higher ammonium consumption in some fermentations correlated with a greater synthesis of glycerol, acetate, and acetaldehyde but with a lower synthesis of higher alcohols.  相似文献   

Increasing resistance to Fusarium crown and root rot in asparagus by gametophyte selection     

Ana Clara Pontaroli  Elsa Lucila Camadro 《Euphytica》2001,122(2):343-350

In garden asparagus, Fusarium crown and root rot is the main cause of crop decline. Since chemical treatments are inefficient, efforts should focus on the development of resistant cultivars to control the disease. Toxic culture filtrate (TCF) of F. oxysporum has affected asparagus pollen germination and tube growth. Consequently, gametophyte selection was evaluated to ascertain if the application of selective agents at this level could increase selection efficiency. Two susceptible pistillate plants and one tolerant and one susceptible staminate plants were used in controlled crosses. Before pollination, a drop of a germination vehicle with TCF or without it was applied to the stigmas. Some pollinated pistils were fixed and analyzed by fluorescence microscopy; the rest were left on the plant for seed production. Fifty to 200 seeds were obtained per treatment combination (staminate plant x pistillate plant x pollination vehicle). The derived plantlets were inoculated in vitroand evaluated for disease symptoms. The application of TCF to stigmas reduced pollen germination and tube growth compared with untreated controls,regardless of the genotypic combination. Pollen germination and tube growth was poorer for the tolerant staminate genotype than for the susceptible one. When the TCF was applied, the number of seeds per pollination in comparison with the controls diminished only when the susceptible genotype was the pollinator. The percentage of affected root area of the progenies obtained after applying the TCF was lower than in the controls only when the tolerant genotype was the pollinator. Increasing Fusarium resistance in asparagus by means of gametophyte selection seems feasible. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Incubation of embryos and larvae of marine fish using microtiter plates     

Elsa B. Panini  Constantinos C. Mylonas  Sylvia Zanuy  Manuel Carrillo  Jesus Ramos  Michael P. Bruce 《Aquaculture International》2001,9(2):189-196

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Performance of purebred and crossbred progeny of White Leghorn and New Hampshire sires     

M. Taran  Elsa Gabriel  E. Moses  M. Soller 《British poultry science》1972,13(4):331-339

Data from a reciprocal recurrent selection (RRS) programme involving a White Leghorn and a New Hampshire flock were analysed to determine whether there were genetic differences in the purebred population that came to expression primarily in the crossbred progeny. The RRS programme had been in use for four years. The White Leghorn flock had previously been the subject of long‐continued and intensive family selection. The New Hampshire flock was less highly selected. Egg number, egg weight and body weight were the primary traits under selection. Each year the programme involved about 10 sires and 80 females of each breed, and about 400 offspring of each type of cross.

The overall economic value of the crossbreds consistently exceeded the mid‐parent mean, the difference increased steadily during the RRS programme. Heritabilities of the various traits were higher when calculated on the basis of crossbred offspring than when calculated on the basis of purebred offspring. For egg production in the White Leghorns there was a fairly low correlation between purebred and crossbred offspring of the same male. For other traits in both breeds the correlation between purebred and crossbred offspring was moderately high. There was a significant interaction between males and breed of females for all traits and breeds, except for egg number in the New Hampshire. These results are consistent with the notion that there were genetic differences between the purebred males (particularly the White Leghorn males) that affected the production characteristics of their crossbred progeny differently than their purebred progeny.  相似文献   

Ocular findings in two colonies of gray mouse lemurs (Microcebus murinus)     

Beltran WA  Vanore M  Ollivet F  Nemoz-Bertholet F  Aujard F  Clerc B  Chahory S 《Veterinary ophthalmology》2007,10(1):43-49

OBJECTIVE: To determine the incidence and describe the characteristics of cataracts and other ocular lesions found in two colonies of gray mouse lemurs (Microcebus murinus). ANIMALS STUDIED: A total number of 218 mouse lemurs (age range: 4 months-11 years) were included in this study. All individuals were property of the Muséum National d'Histoire Naturelle (France), and were housed either in Paris (colony #1: 75 animals examined), or in Brunoy (colony #2: 143 animals). METHODS: Ocular examinations were performed on all animals before and after pupil dilation, and included slit-lamp biomicroscopy and indirect ophthalmoscopy. In both colonies, a limited number of individuals were re-examined between several months and 2 years following the initial eye examinations. The eyes of five mouse lemurs with incipient or immature cataracts that died during this period were collected, and processed for routine histopathologic examination. RESULTS: A high incidence of cataracts was observed in both colonies (48% in colony #1; 21% in colony #2). Cataracts were predominantly bilateral, started in the anterior and/or posterior subcapsular area, and appeared to be slowly progressive. The earliest age at which lens opacities were observed was 3.5 years, and more than 50% of mouse lemurs over 7 years of age were diagnosed with cataracts. Complete cataracts led to blindness and were occasionally associated with other ocular lesions. CONCLUSION: We report a high incidence of acquired, slowly progressive, bilateral cataracts in two colonies of mouse lemurs (Microcebus murinus). Further studies need to be conducted to determine the cause of this disease in this species.  相似文献