Short-Term Dinoflagellate Bloom in a Shrimp Pond in Bahía de La Paz,Gulf of California     

Ismael Gárate-Lizárraga  David J. López-Cortés  José J. Bustillos-Guzmán  Christine J. Band-Schmidt  María Del Socorro Muñetón-Gómez 《Journal Of Applied Aquaculture》2013,25(3):235-246

From mid-August to mid-September 1998, a dinoflagellate bloom in a shrimp pond near La Paz, Baja California Sur, was studied. Daily samples were taken of phytoplankton, dissolved oxygen, nutrient concentrations, photosynthetic pigments and proteins. The bloom occurred at temperatures of 29.7 to 33.2?°C. High densities of a Scrippsiella-like dinoflagellate (15.9?×?10⁶ cells/L) occurred on the first day of sampling, reaching a peak of 249?×?10⁶ cells/L on Day 13, and declining to 4 to 7?×?10⁶ cells/L by Day 26. Chlorophyll a varied from 8.63 mg/m³ on Day 4 to 141.38 mg/m³ on Day 13. Total nitrogen varied widely (0.2–11.50 μM) while phosphates peaked only once on Day 13 (4.14 μM). Proteins ranged from 523 to 6387 μg/L; the latter value occurred two days after the maximal peak of nitrates and coinciding with the highest level of phosphates. Fertilizers added to the ponds increased nutrient concentration and stimulated phytoplankton growth. In turn, the food supply to cultured shrimp noticeably increased throughout the bloom.  相似文献   

Effect of Frozen Storage Temperature on Quality-Related Changes in Rainbow Trout (Oncorhynchus mykiss)     

Maria G. Burgaard  Bo M. Jørgensen 《Journal Of Aquatic Food Product Technology》2013,22(1):53-63

The effect of frozen storage temperature on quality-related parameters of rainbow trout (Oncorhynchus mykiss) muscle was studied in the interval from ?10 to ?80°C on samples stored for 1 to 18 months. The following quantities were measured: drip loss, water holding capacity and water distribution, color, lipid oxidation (thiobarbituric acid-reactive substances, TBARS), and membrane stability (enzyme activity). No effect of temperature on drip loss, water holding capacity, water distribution, or membrane stability was observed for samples stored below ?20°C, whereas storage at ?40°C or lower compared to ?30°C or higher resulted in a reduced level of secondary lipid oxidation (TBARS). No advantage was gained by using temperatures below ?40°C for frozen storage of trout regarding any of the properties investigated.  相似文献   

Bioindicator role of aquatic Ranunculus in Mediterranean freshwater habitats     

Ana Lumbreras  Cristina Pardo  José Antonio Molina 《水产资源保护:海洋与淡水生态系统》2013,23(4):582-593

Effects of different bronopol treatments on final survival rates in the artificial incubation of crayfish eggs (Pacifastacus leniusculus,Astacidae)     

Álvaro González  Jesús D. Celada  Pedro M. Melendre  José M. Carral  María Sáez‐Royuela  Rocío González  Vanesa García 《Aquaculture Research》2013,44(3):354-358

Two experiments were conducted on the effects of bronopol in the artificial incubation of crayfish eggs (Pacifastacus leniusculus) with the aim to search an alternative to formaldehyde. In the first experiment, 50, 250, 500 and 1000 ppm bronopol and 3000 ppm formaldehyde (control) in periodical administrations were tested on a density of 6.6 eggs cm^?2. After 44 days of incubation, the highest survival was obtained with 1000 ppm bronopol (81.9% to stage 2 juvenile, with no significant difference from formaldehyde), whereas lower bronopol concentrations resulted in significantly lower survival. In the second experiment, 1000, 3000 and 5000 ppm bronopol and 3000 ppm formaldehyde (control) administered for 15 min every second day were tested on eggs at a density of 20 eggs cm^?2. After 78 days of incubation, bronopol at 3000 ppm allowed for a stage 2 juvenile survival rate of 65.0% (with no significant difference from formaldehyde), whereas significantly lower survival was obtained with 1000 ppm or 5000 ppm. This study shows that bronopol may constitute an alternative to formaldehyde in the artificial incubation of crayfish eggs. A concentration of 3000 ppm administered for 15 min every second day may be adequate even on long incubations at high densities (at least 20 eggs cm^?2, one complete layer).  相似文献   

Sensitivity of ephemeral wetland swards with Isoetes histrix Bory to environmental variables: implications for the conservation of Mediterranean temporary ponds     

Simonetta Bagella  Maria Carmela Caria 《水产资源保护:海洋与淡水生态系统》2013,23(2):277-290

Glyphosate-resistant weeds of South American cropping systems: an overview     

Vila-Aiub MM  Vidal RA  Balbi MC  Gundel PE  Trucco F  Ghersa CM 《Pest management science》2008,64(4):366-371

Herbicide resistance is an evolutionary event resulting from intense herbicide selection over genetically diverse weed populations. In South America, orchard, cereal and legume cropping systems show a strong dependence on glyphosate to control weeds. The goal of this report is to review the current knowledge on cases of evolved glyphosate-resistant weeds in South American agriculture. The first reports of glyphosate resistance include populations of highly diverse taxa (Lolium multiflorum Lam., Conyza bonariensis L., C. canadensis L.). In all instances, resistance evolution followed intense glyphosate use in fruit fields of Chile and Brazil. In fruit orchards from Colombia, Parthenium hysterophorus L. has shown the ability to withstand high glyphosate rates. The recent appearance of glyphosate-resistant Sorghum halepense L. and Euphorbia heterophylla L. in glyphosate-resistant soybean fields of Argentina and Brazil, respectively, is of major concern. The evolution of glyphosate resistance has clearly taken place in those agroecosystems where glyphosate exerts a strong and continuous selection pressure on weeds. The massive adoption of no-till practices together with the utilization of glyphosate-resistant soybean crops are factors encouraging increase in glyphosate use. This phenomenon has been more evident in Argentina and Brazil. The exclusive reliance on glyphosate as the main tool for weed management results in agroecosystems biologically more prone to glyphosate resistance evolution.  相似文献   

Development of real-time PCR systems based on SYBR^? Green I and TaqMan^? technologies for specific quantitative detection of Phoma tracheiphila in infected Citrus     

Maria Antonietta Demontis  Santa Olga Cacciola  Marcella Orrù  Virgilio Balmas  Valentina Chessa  Bianca Elena Maserti  Laura Mascia  Francesco Raudino  Gaetano Magnano di San Lio  Quirico Migheli 《European journal of plant pathology / European Foundation for Plant Pathology》2008,120(4):339-351

Real-time PCR assays based on SYBR? Green I and TaqMan? technologies were developed for in planta detection and quantification of Phoma tracheiphila, the mitosporic fungus causing ‘mal secco’ disease on citrus. Primers and a hybridization probe were designed on the basis of the internal transcribed spacer (ITS) region of the nuclear rRNA genes. The real-time PCR assays were compared with a classic isolation method in two separate experiments carried out on 6 and 24 month-old sour orange seedlings, artificially inoculated with a conidial suspension of the pathogen. Both technologies made it possible to follow the progression of infection by P. tracheiphila, enabling detection and quantification of the target fungus prior to the development of symptoms. The detection limit was 10 copies of the cloned target sequence and 15 pg of genomic DNA extracted from fungal spores. The values of the cycle threshold (Ct) were linearly correlated with the concentration of the target DNA, indicating that the method is suitable as a qualitative and quantitative assay. The presence of non-target fungal DNA had no effect on the specificity of the assay, but resulted in a 10-fold reduction of sensitivity. Total inhibition of the reaction occurred when conidia of the target pathogen were mixed with an organic soil substrate before extracting DNA using the standard protocol, while an alternative purification kit resulted in a significant decrease in sensitivity. Compared to classic methods, real-time PCR proved faster and easier to perform and showed a higher sensitivity. These results suggest that real-time PCR, based on both chemistries, has a great potential for early diagnosis of ‘mal secco’ disease and for quantitative estimation of fungal growth within host tissue.  相似文献   

Artificial infection of Vaccinium vitis-idaea L. and defence responses to Exobasidium species     

Tuija Pehkonen  Janne Koskimki  Kaisu Riihinen  Anna Maria Pirttil  Anja Hohtola  Laura Jaakola  Anne Tolvanen 《Physiological and Molecular Plant Pathology》2008,72(4-6):146-150

An inoculation method for Exobasidium splendidum and Exobasidium vaccinii was developed on the dwarf shrub Vaccinium vitis-idaea. Using inoculated ramets, we investigated whether there are differences between V. vitis-idaea populations in the susceptibility to Exobasidium infections and whether the defence reaction of V. vitis-idaea is visible at a molecular level. Sixteen V. vitis-idaea clones from four populations were propagated in tissue cultures and the ramets were inoculated with E. splendidum or E. vaccinii fungi. The expression of three flavonoid biosynthetic genes (chalcone synthase, dihydroflavonol 4-reductase and anthocyanidin synthase) and the accumulation of flavonoids and hydroxycinnamic acids were determined in response to E. splendidum infection. A pathogenesis-related (PR 4) gene was isolated and its expression was studied in host ramet leaves. To our knowledge, this was the first successful artificial infection reported with E. splendidum. Disease frequencies of the inoculated ramets were between 32% and 47% for E. splendidum and 33% for E. vaccinii, but below 10% in uninoculated control ramets. There were no differences in disease frequencies between V. vitis-idaea populations. Both symptomatic leaves and healthy leaves of diseased ramets showed activation of flavonoid biosynthesis at the gene level, whereas expression of PR 4 was observed only in symptomatic leaves. The increase of flavonoid biosynthesis in healthy leaves of diseased ramets may represent a general response to stress or a role in defence against the pathogen E. splendidium. Ability of V. vitis-idaea to defend chemically against Exobasidium fungi and the heterogeneity of genotypes, age, size, and growth rates in host plant populations might be reasons for the low infection incidence of Exobasidia in nature.  相似文献   

Vegetative compatibility of cotton-defoliating <Emphasis Type="Italic">Verticillium dahliae</Emphasis> in Israel and its pathogenicity to various crop plants   总被引：2，自引：0，他引：2  

Nadia Korolev  Encarnación Pérez-Artés  Jesús Mercado-Blanco  José Bejarano-Alcázar  Dolores Rodríguez-Jurado  Rafael M. Jiménez-Díaz  Talma Katan  Jaacov Katan 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(4):603-617

Verticillium dahliae isolates recovered from a new focus of severe Verticillium wilt of cotton in the northeast of Israel were tested for vegetative compatibility using nitrate non-utilizing (nit) mutants and identified as VCG1, which is a new record in Israel. Other cotton isolates of V. dahliae from the northern and southern parts of the country were assigned to VCG2B and VCG4B, respectively. VCG1 isolates induced severe leaf symptoms, stunting and defoliation of cotton cv. Acala SJ-2, and thus were characterized as the cotton-defoliating (D) pathotype, whereas isolates of VCG2B and VCG4B were confirmed as the earlier described defoliating-like (DL) and non-defoliating (ND) pathotypes, respectively. This is the first record of the D-pathotype in Israel. The host range of representative isolates of each VCG-associated pathotype was investigated using a number of cultivated plants. Overall, the D isolates were more virulent than DL isolates on all tested host plants, but the order of hosts (from highly susceptible to resistant) was the same: okra (Hibiscus esculentus local cultivar), cotton (Gossypium hirsutum cv. Acala SJ2), watermelon (Citrullus lanatus cv. Crimson Sweet), safflower (Carthamus tinctorius cv. PI 251264), sunflower (Helianthus annuum cv. 2053), eggplant (Solanum melongena cv. Black Beauty), and tomato (Lycopersicon esculentum cv. Rehovot 13). The pattern of virulence of ND isolates differed from that of D and DL isolates, so that the former were highly virulent on eggplant but mildly virulent on cotton. Tomato was resistant to all cotton V. dahliae isolates tested. RAPD and specific PCR assays confirmed that the D isolates from Israel were similar to those originating from other countries.  相似文献   

Stable recombinant alpaca antibodies for detection of Tulip virus X     

Jules Beekwilder  Adèle van Houwelingen  José van Beckhoven  Arjen Speksnijder 《European journal of plant pathology / European Foundation for Plant Pathology》2008,121(4):477-485

For detection of the plant pathogenic Tulip virus X (TuVX), a panel of six recombinant antibodies was identified. To this end, a repertoire of variable domains from heavy-chain immunoglobulins (VHH) was cloned from an alpaca, which had been immunized with TuVX. Binding domains were selected by phage display and panning on immobilized TuVX particles. Recombinant VHH antibodies were tested for sensitivity in a sandwich ELISA, and were demonstrated to be readily able to distinguish TuVX-infected tulip leaf material from uninfected leafs. No cross-reactivity of the VHH antibodies to related flexiviridae was observed. Recombinant VHHs maintained their reactivity upon storage at −20°C for over a year. The effect of incubation at higher temperatures for prolonged time was studied. Two out of three VHH proteins retained activity after several weeks of storage at 37°C.  相似文献