Lobster larval transport in the southern Gulf of St. Lawrence     

JOËL CHASSÉ  ROBERT J. MILLER 《Fisheries Oceanography》2010,19(5):319-338

A bio‐physical semi‐Langrangian model was developed to follow the drift and abundance of lobster larvae from hatching to settlement as post‐larvae. The geographic domain encompasses Northumberland Strait and the areas surrounding Prince Edward Island in the southern Gulf of St. Lawrence. The model was run for ten larval seasons, 1983–87 and 1997–2001, representing two periods of egg production. The model was forced with tides, winds, heat fluxes, and marine and freshwater fluxes at open boundaries. Biological inputs were location, date, and density of larvae at hatching, development rates, a time window and a minimum bottom temperature required for successful settlement, and two scenarios of daily mortality. Net drift was west to east but stronger on the north than the south side of Prince Edward Island. The hatch was greater in the second 5‐yr period, but the spatial patterns of settlement were similar. For both mortality scenarios, the same five of the 24 larval source areas were important in providing settlers. Horizontal shear of larval distribution indicates fishing communities were dependent on the hatch from fishing grounds of multiple upstream communities. Variation in daily and annual post‐larval settlement was greatest north of Prince Edward Island. From the 24 source areas there was an eightfold range in the fraction of larvae surviving to settlement, with advection into deep water an important cause of mortality. Four to five possible fishery management areas were identified using multidimensional scaling to group sink areas having shared source areas. We hypothesize leaky discontinuity in connectivity between these groups.  相似文献   

Adjustment Stresses on Rural Laborers in the Mississippi Delta and the Ozarks     

MARY JO GRINSTEAD-SCHNEIDER  BERNAL L. GREEN 《Growth and change》1978,9(3):36-43

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Location of New Firms: Influence of Commuting Behaviour          下载免费PDF全文

Mikaela Backman  Charlie Karlsson 《Growth and change》2017,48(4):682-699

In the entrepreneurship literature, it is generally assumed that an individual establishes a new firm in a location in which they have strong ties, normally in the municipality of residence or employment. We scrutinise this general assumption and show that firm location depends on individual characteristics, such as the commuting experience. Our results show that commuting influences the firm location choice. The probability of establishing a firm in the work municipality increases if the entrepreneur is a commuter, holding constant the type of region and unobservable and observable individual features.  相似文献   

Rapid advance of spring arrival dates in long-distance migratory birds     

Jonzén N  Lindén A  Ergon T  Knudsen E  Vik JO  Rubolini D  Piacentini D  Brinch C  Spina F  Karlsson L  Stervander M  Andersson A  Waldenström J  Lehikoinen A  Edvardsen E  Solvang R  Stenseth NC 《Science (New York, N.Y.)》2006,312(5782):1959-1961

Several bird species have advanced the timing of their spring migration in response to recent climate change. European short-distance migrants, wintering in temperate areas, have been assumed to be more affected by change in the European climate than long-distance migrants wintering in the tropics. However, we show that long-distance migrants have advanced their spring arrival in Scandinavia more than short-distance migrants. By analyzing a long-term data set from southern Italy, we show that long-distance migrants also pass through the Mediterranean region earlier. We argue that this may reflect a climate-driven evolutionary change in the timing of spring migration.  相似文献   

Electrical stimulation affects metabolic enzyme phosphorylation, protease activation, and meat tenderization in beef     

Li CB  Li J  Zhou GH  Lametsch R  Ertbjerg P  Brüggemann DA  Huang HG  Karlsson AH  Hviid M  Lundström K 《Journal of animal science》2012,90(5):1638-1649

ABSTRACT: The objective of this study was to investigate the response of sarcoplasmic proteins in bovine LM to low-voltage electrical stimulation (ES; 80 V, 35 s) after dressing and its contribution to meat tenderization at an early postmortem time. Proteome analysis showed that ES resulted in decreased (P < 0.05) phosphorylation of creatine kinase M chain, fructose bisphosphate aldolase C-A, β-enolase, and pyruvate kinase at 3 h postmortem. Zymography indicated an earlier (P < 0.05) activation of μ-calpain in ES muscles. Free lysosomal cathepsin B and L activity increased faster (P < 0.05) in ES muscles up to 24 h. Immunohistochemistry and transmission electron microscopy further indicated that lysosomal enzymes were released at an early postmortem time. Electrical stimulation also induced ultrastructural disruption of sarcomeres. In addition, ES accelerated (P < 0.05) the depletion of ATP, creatine phosphate, and glycogen, as well as a pH decline and the more preferred pH/temperature decline mode. Finally, ES accelerated meat tenderization, resulting in lesser (P < 0.05) shear force values than the control over the testing time. A possible relationship was suggested between a change in the phosphorylation of energy metabolic enzymes and the postmortem tenderization of beef. Our results suggested the possible importance of the activation of μ-calpain, phosphorylation of sarcoplasmic proteins, and release of lysosomal enzymes for ES-induced tenderization of beef muscle.  相似文献   

Cloning of the short-tailed Gyeongju Donggyeong dog via SCNT: conserving phenotypic inheritance     

Yoo Bin CHOI  Geon A KIM  Hyun Ju OH  Min Jung KIM  Young Kwang JO  Erif Maha Nugraha SETYAWAN  Seok Hee LEE  Byeong Chun LEE 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2016,78(2):329-331

Somatic cell nuclear transfer is a useful tool to maintain genetic information of animals. The Gyeongju Donggyeong dog is a breed registered as natural monument in Korea. The unique feature of the Donggyeong dog is its tail, as the Donggyeong dog can be classified as either short tailed or tailless. The aim of this study was to preserve the Donggyeong dog’s unique feature by cloning. Fibroblasts were obtained from a short-tailed Donggyeong dog. In vivo matured oocytes were enucleated, microinjected with a donor cell and fused electrically. Reconstructed embryos were transferred to six recipient dogs. One surrogate became pregnant, and one short-tailed Donggyeong dog was delivered. This study demonstrated that the phenotype of the Donggyeong dog could be conserved by somatic cell nuclear transfer.  相似文献   

Ozone and drought stress — Interactive effects on the growth and physiology of Norway spruce (Picea abies (L.) Karst.)     

P. E. Karlsson  E.-L. Medin  H. Wickström  G. Selldén  G. Wallin  S. Ottosson  L. Skärby 《Water, air, and soil pollution》1995,85(3):1325-1330

Young trees of Norway spruce (Picea abies (L.) Karst.) were grown in 120 litre pots under two different ozone levels in open-top chambers for three seasons, 1992–1994. The ozone treatments were charcoal filtered air (CF, average 24 h seasonal mean 6.5 ppb) and non-filtered air with extra ozone aiming to track 1.5 times ambient (NF+, average seasonal mean 34 ppb). In addition, half of the spruce trees in Aug – Sep each season recieved a drought period of between five and seven weeks. The remaining half were kept well-watered. The soil water content, the needle water potentials, and the gas exchange as well as the chamber micro climate were measured before, during and after the drought period. Furthermore, the growth of the trees was measured as biomass increase. During the 1993 drought period, where the trees experienced a moderate drought stress, the trees grown in NF+ consumed soil water faster and showed a higher needle conductance compared to CF. However, no negative effects were found on needle water potential or growth. During the more severe 1994 drought stress period we did not find any differences between the two ozone treatments in soil water consumption, needle conductance or needle water potential. There was a significant negative effect of the high ozone treatment on tree biomass of the well-watered trees. Total plant biomass was reduced 18 % and stem biomass was reduced as much as 28 %. The negative effect of ozone on tree biomass was much smaller for the droughted trees.  相似文献   

Degradation of hemicellulose, cellulose and lignin in decomposing spruce needle litter in relation to N     

G. Sjöberg  S.I. Nilsson  P. Karlsson 《Soil biology & biochemistry》2004,36(11):1761-1768

Decomposing needles from a Norway spruce forest in southern Sweden were studied for 559 days under laboratory conditions. Falling needles were collected in control (Co) plots and plots that had received 100 kg N ha⁻¹ yr⁻¹ as (NH₄)₂SO₄ for 9 years under field conditions. One of the aims was to determine whether the previously documented low decomposition rate of the N fertilized (NS) needles could be explained by a lower degradation degree of lignin. The lignin content was studied using the alkaline CuO oxidation method, the Klason lignin method and CPMAS ¹³C NMR spectroscopy. The amounts of cellulose and hemicellulose were also determined.The fertilized needle litters initially decomposed faster than the unfertilized, but later this reaction reversed, so that at the end the mass loss was 45% initial C in the control and 35% initial C in NS. Klason lignin decreased with time in both treatments and overall, the change of Klason lignin mirrored the litter mass loss. No major difference as regards the decomposition of hemicellulose occurred between the treatments, whereas significantly lower concentrations of cellulose were found in NS needles throughout the incubation. The CuO derived compounds (VSC) were somewhat lower in NS needles throughout the decomposition time. Initially, VSC increased slightly in both treatments, which contradicts the Klason lignin data. There was a weak positive relationship (p>0.05) between VSC and Klason lignin. Both vanillyls compounds (V) and cinnamyl compounds (Ci) increased slightly during decomposition, whereas syringyl compounds (S) vanished entirely. The lignin degradation degree, i.e. the acid-to-aldehyde ratio of the vanillyl compounds expressed as (Ac/Al)_v, showed no significant effect of treatment. The ¹³C NMR analyses of the combined samples showed increased content of aromatic C with increasing decomposition time. The carbohydrate content (O-alkyl C) was lower in the fertilized needle litter throughout the incubation time. The alkyl C content tended to increase with decomposition time and N fertilization. The alkyl C/O-alkyl C ratios increased in both treatments during the incubation. The NMR results were not tested statistically.In conclusion, no major difference concerning lignin degradation could be found between the unfertilized and N fertilized needle litter. Thus, the study contradicts the hypothesis that higher amounts of N reduce lignin degradation. The reduced biological activity is probably due to direct N effects on the microorganisms and their decomposing ability.  相似文献   

Investigations of factors that influence the acrylamide content of heated foodstuffs     

Rydberg P  Eriksson S  Tareke E  Karlsson P  Ehrenberg L  Törnqvist M 《Journal of agricultural and food chemistry》2003,51(24):7012-7018

The acrylamide content of heated foodstuffs should be considered to be the net result of complex reactions leading to the formation and elimination/degradation of this compound. The present study, involving primarily homogenized potato heated in an oven, was designed to characterize parameters that influence these reactions, including the heating temperature, duration of heating, pH, and concentrations of various components. Higher temperature (200 degrees C) combined with prolonged heating times produced reduced levels of acrylamide, due to elimination/degradation processes. At certain concentrations the presence of asparagine or monosaccharides (in particular, fructose and also glucose and glyceraldehyde) was found to increase the net content of acrylamide. Addition of other free amino acids or a protein-rich food component strongly reduced the acrylamide content, probably by promoting competing reactions and/or covalently binding acrylamide formed. The dependence on pH of the acrylamide content exhibited a maximum around pH 8; in particular, lower pH was shown to enhance elimination and decelerate formation of acrylamide. In contrast, the effects of additions of antioxidants or peroxides on acrylamide content were small or nonexistent.  相似文献   

Dilatation of the Ampullae and an Increased Incidence of Loose Sperm Heads after Bilateral Vesiculectomy in a Bull     

JO Nöthling  DH Volkmann 《Reproduction in domestic animals》1997,32(6):321-324

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