A molecular and embryonic study of apomixis in cassava (Manihot esculenta Crantz)     

Nagib M.A. Nassar  Marco Andre Vieira  Clibas Vieira  Dario Grattapaglia 《Euphytica》1998,102(1):9-13

In cassava, apomixis fixes heterosis and avoids transmission of systemic pathogens which complicate vegetative propagation of the crop. A combination of evidence from maternal inheritance of RAPD markers and the structure of the embryonic sac in large progeny sets of two distinct genotypes have further confirmed the occurrence of apomixis in cassava. We could advance further on earlier reports of the detection of apomixis in four ways: (1) we could arrive at an estimate of the rate of facultative apomixis in the range of 2%; (2) we detected the occurrence of apomixis in a second genotype, derived from a different interspecific cross; (3) apomictic behavior was demonstrated in an F₁ individual and (4) parallel embryonic evidence was generated that corroborate the potential occurrence of apomixis by apospory. The fact that apomixis was detected in an F₁ interspecific hybrid hints to the possibility of directly transferring genes for apomixis from a wild relative to cultivated cassava. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Abdominal puncture as a new method to determine sex in tuviras (Gymnotus sp.)     

Marco Antonio Thomaz  Antonio Cleber da Silva Camargo  Bruno Leite dos Anjos  Carlos Frederico Ceccon Lanes 《Aquaculture Research》2019,50(6):1651-1657

Tuviras (Gymnotus sp.) are a small fish widely used as live bait in sport fishing. Interest in its culture has increased, but there are still several bottlenecks that need to be solved. For example, the process of sexing in tuviras is difficult since they do not present sexual dimorphism. Thus, the aim of this study was to verify if an abdominal puncture could be used as an inexpensive, fast and reliable technique to identify the sex of adult Gymnotus sp. Before performing the abdominal puncture, five individuals were dissected to determine the exact location of the gonads. Based on this information, the abdominal puncture was performed 6 cm away from the tip of the animal's head and 1 cm below the lateral line with an intravenous infusion set connected to a 5 ml syringe. An abdominal puncture was performed on 24 adult animals that were larger than 20 cm in length. Twenty‐two individuals were sexed correctly, and the accuracy degree was 91.66%. The survival rate of the animals 96 hr after the abdominal puncture was 100%. These results indicate that the abdominal puncture is an easy, simple, fast and inexpensive technique that can be performed in a reliable way.  相似文献   

Systemic infection in European perch with thermoadapted virulent Aeromonas salmonicida (Perca fluviatilis)     

Melanie Rupp  Paola Pilo  Barbara Müller  Ralph Knüsel  Beat von Siebenthal  Joachim Frey  Paul‐Daniel Sindilariu  Heike Schmidt‐Posthaus 《Journal of fish diseases》2019,42(5):685-691

In non‐salmonid fish, Aeromonas salmonicidacan cause local infections with severe skin ulcerations, known as atypical furunculosis. In this study, we present a systemic infection by a virulent A. salmonicidain European perch (Perca fluviatilis).This infection was diagnosed in a Swiss warm water recirculation aquaculture system. The isolate of A.  salmonicida encodes a type three secretion system (TTSS) most likely located on a plasmid similar to pAsa5/pASvirA, which is known to specify one of the main virulence attributes of the species A. salmonicida. However, the genes specifying the TTSS of the perch isolate show a higher temperature tolerance than strains isolated from cold‐water fish. The function of the TTSS in virulence was verified in a cytotoxicity test using bluegill fry and epithelioma papulosum cyprinid cells.  相似文献   

Trophic mass balanced models and dynamic simulations of benthic communities from La Rinconada Marine Reserve off northern Chile: network properties and multispecies harvest scenario assessments     

Marco Ortiz  Miguel Avendaño  Marcela Cantillañez  Fernando Berrios  Leonardo Campos 《水产资源保护:海洋与淡水生态系统》2010,20(1):58-73

• 1. Mass balanced trophic models and dynamic simulations of two benthic ecological systems from La Rinconada Marine Reserve (Antofagasta Bay, SE Pacific) were constructed.
• 2. The scallop Argopecten purpuratus is the most important benthic resource in La Rinconada Marine Reserve, followed by the carnivorous snail Thais chocolata, and the filter‐feeder bivalves Tagelus dombeii and Transennella pannosa.
• 3. Information on biomass, P/B ratios, catches, food spectrum, consumption, and dynamics of commercial and non‐commercial species was obtained and examined using Ecopath with an Ecosim software package.
• 4. The bivalves A. purpuratus and T. dombeii represented the most abundant compartments in the studied subsystems. Of the carnivores, the snail T. chocolata was dominant, followed by the crabs Cancer spp. and the functional group of large epifauna.
• 5. The two subsystems presented similar values of system throughput. The mean trophic level of their fisheries also reached similar magnitudes (2.0), showing that the harvests in each system concentrated on secondary producers. Likewise, both subsystems presented similar A/C ratios (29.9 and 30.3), suggesting that they were immature.
• 6. The results obtained using mixed trophic impact (MTI) and Ecosim (increasing the fishing mortality F_i by four times) showed that only four species propagated the highest direct and indirect effects. Coincidentally, these species are the most economically important and the changes produced by the scallop A. purpuratus are noteworthy.
• 7. With regard to the system recovery time (SRT) estimates, only three species or functional groups presented the highest magnitudes, from highest to lowest: the sea star Luidia magallanica, the scallop A. purpuratus, and the crabs Cancer spp.
• 8. The topological keystone indexes of Jordán and Libralato had divergent results. According to Jordán's index, the keystone species were L. magallanica, Cancer spp., and detritus; whereas Libralato's index showed phytoplankton to be the keystone species.
• 9. Based on the results obtained, it is concluded that trophic mass balanced models and simulated management scenarios have considerable value for planning interventions and manipulations or for planning more sustainable management strategies in La Rinconada Marine Reserve. Copyright © 2009 John Wiley & Sons, Ltd.

  相似文献   

Dynamic and spatial models of kelp forest of Macrocystis integrifolia and Lessonia trabeculata (SE Pacific) for assessment harvest scenarios: short‐term responses     

Marco Ortiz 《水产资源保护:海洋与淡水生态系统》2010,20(5):494-506

1. Dynamic and spatial models of the kelp forest off northern Chile (SE Pacific coast) were constructed using the Ecosim and Ecospace theoretical frameworks based on a previously mass‐balanced trophic model using Ecopath II software. 2. The biomass of Macrocystis integrifolia and Lessonia trabeculata blades constituted the most relevant compartments or variables of the ecosystem studied. 3. The relative ascendency (A/C) of 35.5% suggests that this ecosystem is immature, but resistant to disturbances (e.g. fisheries). 4. The results obtained using mixed trophic impacts (MTI) show that both brown macroalgae produced relatively similar quantitative and qualitative effects, however, the predictions based on Ecosim clearly show that L. trabeculata experienced the most relevant direct and indirect effects. 5. The highest values of system recovery time obtained by Pinguipes chilensis and the other seastar group suggest that both compartments could be considered to be top predator species with strong top‐down control. 6. The exploitation of kelp blades as a new harvest strategy appears to be ecologically sustainable. 7. The Ecospace trophic‐spatially explicit model shows that exploitation exerted separately by habitat generates a similar pattern of direct and indirect effects. These results suggest that a habitat rotation of fisheries would not be justified.Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Essential oil of Lippia grata (Verbenaceae) is effective in the control of monogenean infections in Colossoma macropomum gills,a large Serrasalmidae fish from Amazon     

Isaac Belo Barriga  Anai Paola Prissilla Flores Gonzales  Alexandre Renato Pinto Brasiliense  Karina Neoob Carvalho Castro  Marcos Tavares‐Dias 《Aquaculture Research》2020,51(9):3804-3812

This study investigated the efficacy of Lippia grata essential oil (EO) against monogeneans of Colossoma macropomum and effects on the haematology after immersion baths. In the in vitro assays, the efficacy of 100, 250, 350 and 700 mg/L of L. grata EO and two controls were tested, of which one control was with the cultivation tank water and the other was with the tank water and 70% ethyl alcohol. Composition of majority bioactive compounds in the EO was carvacrol (48.12%), p‐cymene (24.39%) and γ‐terpinene (2.49%). Anacanthorus spathulatus, Notozothecium janauachensis, Mymarothecium boegeri and Linguadactyloides brinkmanni obtained of fish gills showed 100% immobilization in the in vitro assays when exposed to 700 and 350 mg/L after 30 min and 2 hr respectively. Fish showed tolerance to 700 mg/L of the EO, which was used in therapeutic in three consecutive baths, which caused lamellar hyperplasia in C. macropomum gills. The 700 mg/L of the EO in the therapeutic baths showed an efficacy of 95.1% against the monogeneans and caused decrease in haemoglobin, whereas control fish showed a reduction in mean corpuscular haemoglobin concentration. Results indicated that 700 mg/L of L. grata EO is a safe and effective concentration to treat C. macropomum infected with monogeneans.  相似文献   

Effects of Pseudoloma neurophilia infection on the brain transcriptome in zebrafish (Danio rerio)     

Helene L.E. Midttun  Marco A. Vindas  Paul J Whatmore  Øyvind Øverli  Ida B. Johansen 《Journal of fish diseases》2020,43(8):863-875

Laboratory zebrafish are commonly infected with the intracellular, brain-infecting microsporidian parasite Pseudoloma neurophilia. Chronic P. neurophilia infections induce inflammation in meninges, brain and spinal cord, and have been suggested to affect neural functions since parasite clusters reside inside neurons. However, underlying neural and immunological mechanisms associated with infection have not been explored. Utilizing RNA-sequencing analysis, we found that P. neurophilia infection upregulated 175 and downregulated 45 genes in the zebrafish brain, compared to uninfected controls. Four biological pathways were enriched by the parasite, all of which were associated with immune function. In addition, 14 gene ontology (GO) terms were enriched, eight of which were associated with immune responses and five with circadian rhythm. Surprisingly, no differentially expressed genes or enriched pathways were specific for nervous system function. Upregulated immune-related genes indicate that the host generally show a pro-inflammatory immune response to infection. On the other hand, we found a general downregulation of immune response genes associated with anti-pathogen functions, suggesting an immune evasion strategy by the parasite. The results reported here provide important information on host–parasite interaction and highlight possible pathways for complex effects of parasite infections on zebrafish phenotypes.  相似文献   

Contrasting land use legacy effects on forest landscape dynamics in the Italian Alps and the Apennines     

Garbarino  Matteo  Morresi  Donato  Urbinati  Carlo  Malandra  Francesco  Motta  Renzo  Sibona  Emanuele Marco  Vitali  Alessandro  Weisberg  Peter J. 《Landscape Ecology》2020,35(12):2679-2694

Landscape Ecology - Land use legacies of human activities and recent post-abandonment forest expansion have extensively modified numerous forest landscapes throughout the European mountain ranges....  相似文献   

Canopy spray deposition and related mortality impacts of commonly used insecticides on Drosophila suzukii Matsumura (Diptera: Drosophilidae) populations in blueberry     

Serhan Mermer  Ferdinand Pfab  Gwen A Hoheisel  Haitham Y Bahlol  Lav Khot  Daniel T Dalton  Linda J Brewer  Marco V Rossi Stacconi  Chengzhu Zhang  Lan Xue  Vaughn M Walton 《Pest management science》2020,76(4):1531-1540

  相似文献   

Phenotypic and genotypic pyrethroid resistance of Aedes albopictus,with focus on the 2017 chikungunya outbreak in Italy     

Verena Pichler  Chiara Malandruccolo  Paola Serini  Romeo Bellini  Francesco Severini  Luciano Toma  Marco Di Luca  Fabrizio Montarsi  Marco Ballardini  Mattia Manica  Vincenzo Petrarca  John Vontas  Shinji Kasai  Alessandra della Torre  Beniamino Caputo 《Pest management science》2019,75(10):2642-2651

  相似文献