Breeding for disease resistance of Penaeid shrimps     

James Cock  Thomas Gitterle  Marcela Salazar  Morten Rye 《Aquaculture (Amsterdam, Netherlands)》2009,286(1-2):1-11

Diseases are a major constraint on the intensive production of shrimps. Conditions in production ponds favour disease development, and epidemics of several previously unreported diseases have occurred and caused severe losses. When elimination, eradication or cultural control is difficult, selective breeding for host resistance to the pathogen may be an attractive option for disease control. However, host resistance is not a panacea and should only be considered when (a) the disease causes severe damage (b) there are no other existing simple cost effective control measures and (c) there is demonstrable genetic variation in resistance and this is not coupled with an excessive level of negative associations with other desirable characteristics. Shrimp have only recently been domesticated and breeding for resistance only began in the mid 1990s; there is limited experience with shrimp breeding in particular and crustaceans in general. Consequently, the principles and concepts behind breeding programmes are based largely on experiences with other species in both the plant and animal kingdoms. Commercial growers now seed ponds with shrimp populations selected for resistance to Taura Syndrome Virus with excellent results, whilst up to now development of White Spot Syndrome Virus resistant populations has been an elusive goal. The original TSV resistant populations were developed using simple mass selection techniques (Colombia). In later generations family based selection has been applied on populations, which initially had survival rates of about 30%, with care taken to reduce inbreeding and loss of genetic variation. This suggests that when the original populations have a reasonable level of resistance, and straightforward, effective selection protocols exist, it is relatively simple to breed for resistance. With catastrophic diseases, such as WSSV, which cause mortalities of 98% or more the frequency of resistance is low and it is suggested that for theoretical reasons single gene, rather than polygenic, resistance is likely to develop. The low frequency of resistance genes in breeding populations may cause genetic bottlenecks which will greatly reduce the genetic variation in the populations. In order to maintain the genetic variation the genes from the small numbers of survivors should be introgressed into populations with broader genetic variability. Furthermore, in order to minimize the probability of breakdown of resistance pyramiding of resistant genes on different loci would be advantageous.Genetic variation in resistance may be encountered either in the initial base populations or may spontaneously arise due to mutations or new recombinants. With extremely prolific species such as shrimps, millions of animals can readily be screened for survival and hence resistant mutants or recombinants may be identified. Once genetic variation has been detected the most appropriate breeding methodology will depend on the nature of both the resistance and the disease or diseases that are of interest to the producers.  相似文献   

Is European research on aquatic food product technology dead?     

Morten Sivertsvik 《Journal Of Aquatic Food Product Technology》2019,28(1)

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An Aboriginal Australian genome reveals separate human dispersals into Asia     

Rasmussen M  Guo X  Wang Y  Lohmueller KE  Rasmussen S  Albrechtsen A  Skotte L  Lindgreen S  Metspalu M  Jombart T  Kivisild T  Zhai W  Eriksson A  Manica A  Orlando L  De La Vega FM  Tridico S  Metspalu E  Nielsen K  Ávila-Arcos MC  Moreno-Mayar JV  Muller C  Dortch J  Gilbert MT  Lund O  Wesolowska A  Karmin M  Weinert LA  Wang B  Li J  Tai S  Xiao F  Hanihara T  van Driem G  Jha AR  Ricaut FX  de Knijff P  Migliano AB  Gallego Romero I  Kristiansen K  Lambert DM  Brunak S  Forster P  Brinkmann B  Nehlich O  Bunce M  Richards M  Gupta R 《Science (New York, N.Y.)》2011,334(6052):94-98

We present an Aboriginal Australian genomic sequence obtained from a 100-year-old lock of hair donated by an Aboriginal man from southern Western Australia in the early 20th century. We detect no evidence of European admixture and estimate contamination levels to be below 0.5%. We show that Aboriginal Australians are descendants of an early human dispersal into eastern Asia, possibly 62,000 to 75,000 years ago. This dispersal is separate from the one that gave rise to modern Asians 25,000 to 38,000 years ago. We also find evidence of gene flow between populations of the two dispersal waves prior to the divergence of Native Americans from modern Asian ancestors. Our findings support the hypothesis that present-day Aboriginal Australians descend from the earliest humans to occupy Australia, likely representing one of the oldest continuous populations outside Africa.  相似文献   

Superconducting vortices in CeCoIn5: toward the Pauli-limiting field     

Bianchi AD  Kenzelmann M  Debeer-Schmitt L  White JS  Forgan EM  Mesot J  Zolliker M  Kohlbrecher J  Movshovich R  Bauer ED  Sarrao JL  Fisk Z  Petrovic C  Eskildsen MR 《Science (New York, N.Y.)》2008,319(5860):177-180

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Periodic changes in the zooplankton of the North Sea during the twentieth century linked to oceanic inflow   总被引：9，自引：0，他引：9  

Philip C. Reid  Martin Edwards  Gregory Beaugrand  Morten Skogen  Darren Stevens 《Fisheries Oceanography》2003,12(4-5):260-269

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Quality of sour cherry juice of different clones and cultivars (Prunus cerasus L.) determined by a combined sensory and NMR spectroscopic approach     

Clausen MR  Pedersen BH  Bertram HC  Kidmose U 《Journal of agricultural and food chemistry》2011,59(22):12124-12130

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Release of dissolved trace metals and organic contaminants during deep water disposal of contaminated sediments from Oslo harbour,Norway     

Morten Thorne Schaanning  Christopher Harman  André Staalstrøm 《Journal of Soils and Sediments》2011,11(8):1477-1489

Purpose  

The current study was conducted in order to assess the release of dissolved contaminants from sediment relocation works in Oslo harbour, Norway, whilst operations were being carried out, and to assess the potential for spreading into the wider fjord area.  相似文献   

Mass of vesta     

Hertz HG 《Science (New York, N.Y.)》1968,160(3825):299-300

The asteroid 197 (Arete) approaches asteroid 4 (Vesta) within 0.04 astronomical unit once every 18 years. It may therefore be possible to determine the mass of Vesta from observations of Arete. From 72 observations a value of (1.20 +/- 0.08) x 10(-10) solar mass was derived, the indicated uncertainty being a probable error.  相似文献   

Pre-Clovis mastodon hunting 13,800 years ago at the Manis site, Washington     

Waters MR  Stafford TW  McDonald HG  Gustafson C  Rasmussen M  Cappellini E  Olsen JV  Szklarczyk D  Jensen LJ  Gilbert MT  Willerslev E 《Science (New York, N.Y.)》2011,334(6054):351-353

The tip of a projectile point made of mastodon bone is embedded in a rib of a single disarticulated mastodon at the Manis site in the state of Washington. Radiocarbon dating and DNA analysis show that the rib is associated with the other remains and dates to 13,800 years ago. Thus, osseous projectile points, common to the Beringian Upper Paleolithic and Clovis, were made and used during pre-Clovis times in North America. The Manis site, combined with evidence of mammoth hunting at sites in Wisconsin, provides evidence that people were hunting proboscideans at least two millennia before Clovis.  相似文献   

Release of emamectin from sediment: effects of oil,organic material or infauna?     

Eirin Sva Stomperudhaugen  Katherine Langford  Morten Schaanning  Ketil Hylland 《Journal of Soils and Sediments》2014,14(8):1469-1478

Purpose

The aim of this study was to quantify the release of the hydrophobic contaminant emamectin (EMA) from marine sediments in response to inputs of organic material (OM) and/or oil, in the presence or absence of two different bioturbating species. Specifically, it was designed to test whether oil would decrease the release of EMA and whether OM and/or the presence of bioturbating macrofauna would increase the release of EMA from sediment.

Materials and methods

Experimental sediments were spiked with EMA (5 μg kg^?1 wet sediment). The different treatments were prepared by the addition of OM (310 g algae m^?2) and/or an aliphatic oil (29.6 g oil m^?2). In addition, two bioturbating species, Brissopsis lyrifera or Ennucula tenuis, were added in some aquaria, resulting in a total of 12 treatments with four replicates each. Water samples for analyses of silicate and EMA and sediment samples for analyses of total organic carbon (TOC) were taken at the start and end of the experimental exposure. In addition, oxygen was measured during the experimental period of 8 days. Fluxes were calculated and compared between treatments using generalised linear models (GLMs).

Results and discussion

The EMA release flux was significantly increased in treatments with added OM, possibly reflecting the presence of soluble complexes formed between EMA and dissolved OM. The presence of B. lyrifera caused a small, but statistically significant, increase in EMA release from sediment. This species would be expected to have a stronger effect on bioirrigation and particle mixing than E. tenuis, particularly when the population density of the latter species is low (as in the present experiment). There were no consistent effects of oil in this experiment, but the presence of oil decreased the EMA release flux when co-occurring with added OM and/or B. lyrifera. Increased retention of hydrophobic contaminants in the presence of oil is consistent with the existing literature on contaminant fate.

Conclusions

The results from this study highlight the need to consider both the infauna present in polluted areas and the level of organic enrichment of the sediment when modelling the environmental fate of hydrophobic contaminants. It also highlights that labile OM and refractory oil appear to differ in their effects on the remobilisation of hydrophobic organic contaminants, by reducing and increasing release, respectively.  相似文献