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271.
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273.
Brian W. Kot Richard Sears Ayal Anis Douglas P. Nowacek Jason Gedamke Christopher D. Marshall 《Journal of experimental marine biology and ecology》2012
Whale entanglement in fishing gear is a global problem, and underwater ropes associated with this gear are often the cause of injuries that can lead to fatalities. Minke whales (Balaenoptera acutorostrata) are especially at risk because they are relatively small, widely distributed, and often occur in coastal habitats where many types of fishing gear are deployed. It is unknown whether minke whales can detect and avoid ropes associated with fishing gear. To address this question we conducted a series of field experiments to measure behavioral responses of nearshore minke whales to underwater ropes simulating crab and whelk fishing gear. We also investigated correlations between whale behaviors and specific environmental variables. Our methods involved both visual and acoustic monitoring of whale behaviors near experimental ropes and buoys of different colors. A remote sensing system was also used to simultaneously monitor oceanographic conditions, record underwater sounds, and capture underwater video of whales swimming near ropes. Minke whales (N = 42) decreased their swimming velocity and altered their bearing when passing near experimental ropes, especially during trials with white and black ropes. Some minkes (N = 7) also altered their underwater swimming trajectories when passing near ropes, and often appeared to produce low-frequency vocalizations. Collectively this information provides strong evidence that minke whales detect and react behaviorally to the presence of underwater ropes that simulate fishing gear in nearshore areas. We hypothesize that visual and perhaps passive acoustic sensory abilities may be the mechanisms behind these rope avoidance behaviors. We recommend that high contrast ropes (white and black) be used with fishing gear in coastal areas to help minimize entanglements of minke and perhaps other whale species. 相似文献
274.
Douae Ben Hdech Catherine Aubry Bénédicte Alibert Daniel Beucher Jean-Marie Prosperi Anis M. Limami Béatrice Teulat 《Physiologia plantarum》2020,170(2):227-247
Seedling pre-emergence is a critical phase of development for successful crop establishment because of its susceptibility to environmental conditions. In a context of reduced use of inorganic fertilizers, the genetic bases of the response of seedlings to nitrate supply received little attention. This issue is important even in legumes where nitrate absorption starts early after germination, before nodule development. Natural variation of traits characterizing seedling growth in the absence or presence of nitrate was investigated in a core collection of 192 accessions of Medicago truncatula. Plasticity indexes to the absence of nitrate were calculated. The genetic determinism of the traits was dissected by genome-wide association study (GWAS). The absence of nitrate affected seed biomass mobilization and root/shoot length ratio. However, the large range of genetic variability revealed different seedling performances within natural diversity. A principal component analysis (PCA) carried out with plasticity indexes highlighted four physiotypes of accessions differing in relationships between seedling elongation and seed biomass partitioning traits in response to the absence of nitrate. Finally, GWAS revealed 45 associations with single or combined traits corresponding to coordinates of accessions on PCA, as well as two clusters of genes encoding sugar transporters and glutathione transferases surrounding loci associated with seedling elongation traits. 相似文献
275.
Embryogenic cultures of soybean [Glycine max (L.) Merr. cv. Jack and Asgrow A2872] were established in liquid Finer and Nagasawa medium, maintained by transfer to fresh
medium at biweekly intervals, and subjected to microprojectile bombardment over time. Cultures were not amenable to transformation
until they were at least 6 months old. Over time, different cell lines of the same genotype acquired very different culture
phenotypes. Histological analysis of cell lines differing in transformation ability showed that the most transformable cultures
had cytoplasmic-rich cells in the outermost layers of the tissue. In contrast, the outer layers of less transformable cultures
contained cells with prominent vacuoles. Although fresh weight accumulation of the cultures was curvilinear during the 2-week
subculture period, a burst of mitotic activity was evident shortly after transfer to fresh medium. This activity usually lasted
from the 2nd to the 6th day following subculture, and peaked on the 4th day. Tissues at or near this stage always produced
more transient expression of a reporter gene than did bombardments at other times. In addition, the cell lines most amenable
to transformation also exhibited the highest mitotic index. Thus any treatment to increase the mitotic index, especially when
the cell lines are less than 6 months old, may facilitate the transformation of cell lines from which efficient recovery of
transgenic plants is still possible.
Received: 16 September 1997 / Revision received: 29 January 1998 / Accepted: 21 February 1998 相似文献
276.
While there is no doubt that social signals affect human reinforcement learning, there is still no consensus about how this process is computationally implemented. To address this issue, we compared three psychologically plausible hypotheses about the algorithmic implementation of imitation in reinforcement learning. The first hypothesis, decision biasing (DB), postulates that imitation consists in transiently biasing the learner’s action selection without affecting their value function. According to the second hypothesis, model-based imitation (MB), the learner infers the demonstrator’s value function through inverse reinforcement learning and uses it to bias action selection. Finally, according to the third hypothesis, value shaping (VS), the demonstrator’s actions directly affect the learner’s value function. We tested these three hypotheses in 2 experiments (N = 24 and N = 44) featuring a new variant of a social reinforcement learning task. We show through model comparison and model simulation that VS provides the best explanation of learner’s behavior. Results replicated in a third independent experiment featuring a larger cohort and a different design (N = 302). In our experiments, we also manipulated the quality of the demonstrators’ choices and found that learners were able to adapt their imitation rate, so that only skilled demonstrators were imitated. We proposed and tested an efficient meta-learning process to account for this effect, where imitation is regulated by the agreement between the learner and the demonstrator. In sum, our findings provide new insights and perspectives on the computational mechanisms underlying adaptive imitation in human reinforcement learning.This study investigates imitation from a computational perspective; three experiments show that, in the context of reinforcement learning, imitation operates via a durable modification of the learner''s values, shedding new light on how imitation is computationally implemented and shapes learning and decision-making. 相似文献
277.
An efficient protocol is described for the rapid in vitro multiplication of an endangered medicinal plant, Tylophora indica (Burm. f.) Merrill, via enhanced axillary bud proliferation from nodal explants collected from young shoots of a two-year-old
plant. The physiological effects of growth regulators [6-benzyladenine (BA), kinetin (Kin) thidiazuron (TDZ), indole-3-acetic
acid (IAA), indole-3-butyric acid (IBA) or α-naphthalene acetic acid (NAA)], ascorbic acid (AA), different strengths of Murashige
and Skoog (MS) medium and various pH levels on in vitro morphogenesis were investigated. The highest number (8.6 ± 0.71) of
shoots and the maximum average shoot length (5.2 ± 0.31 cm) were recorded on MS medium supplemented with 2.5 μM BA, 0.5 μM
NAA and 100 mg/l AA at pH 5.8. Rooting was best achieved on half-strength MS medium augmented with 0.5 μM IBA. The plantlets
regenerated in vitro with well-developed shoot and roots were successfully established in pots containing garden soil and
grown in a greenhouse with a 90% survival rate. The regenerated plants did not show any immediate detectable phenotypic variation.
The described method can be successfully employed for large-scale multiplication and long-term in vitro conservation of T. indica. 相似文献
278.
Pterocarpus marsupium (Bijasal) is a valuable multipurpose forest tree. The regeneration rate in natural habitat is low and the tree is overexploited.
An in vitro propagation protocol has been developed from nodal explants obtained from in vitro raised 18-day-old axenic seedlings.
The highest shoot regeneration frequency (85%), maximum number of multiple shoots (8.6) as well as length (4.8 cm) were induced
from nodal explants on Murashige and Skoog (MS) medium amended with 4.0 μM 6-benzyladenine (BA), 0.5 μM indole-3-acetic acid
(IAA) and 20 μM adenine sulphate (AdS). The percentage of shoot multiplication as well as the number of shoots per node remained
the same during the first two subculture, afterwards a decline was recorded. Rooting was best induced in microshoots excised
from proliferated shoot cultures on semisolid hormone-free half-strength MS medium, after a pulse (dip) treatment for 7 days
in half-strength MS liquid medium containing 100 μM indole-3-butyric acid (IBA) and 15.84 μM phloroglucinol (PG). The in vitro-raised
plantlets were potted and acclimatized under culture room conditions for 4 weeks before their transfer to a greenhouse, where
the established plants showed 75% survival. 相似文献
279.
Anis Kamoun Omar Hammouda Mouna Turki Rami Maaloul Mohamed Chtourou Mohamed Bouaziz Tarak Driss Nizar Souissi Karim Chamari Fatma Ayadi 《Biology of sport / Institute of Sport》2021,38(2):245
The present study aimed to investigate the effect of walnut consumption on lipid profile, steroid hormones and inflammation in trained elderly men performing concurrent (resistance and endurance) training. Twenty healthy elderly males were divided into two matched groups, in a randomized controlled trial, that trained three sessions per week: concurrent training + dietary walnut consumption (15 g/day for six weeks, CTW: n = 10); concurrent training + control diet (CT: n = 10). Fasting blood samples were taken 48 hours before and after intervention for biochemical assessments. levels of high-density lipoprotein (HDL) increased only in CTW compared to baseline (19.8%, p < 0.01). Total cholesterol (TC), low-density lipoprotein (LDL) and triglyceride (TG) levels significantly decreased only for CTW (i.e., 13%, 18%, and 18.5% at p < 0.01 for all). Testosterone (T) increased after the training compared to pre-training for CTW and CT (10.3%, p < 0.01, 4.27% p < 0.05, respectively), but the increase was significantly higher in CTW (p < 0.05). Serum cortisol (C) was lower for CTW compared to CT (p < 0.01). C-reactive protein (CRP) decreased in CTW in comparison with CT. The present study revealed that 6-week moderate walnut supplementation (15 g/day) improved lipid profile, steroid hormones and systematic inflammation in aged men performing concurrent training. These findings could be attributable to the potential effect of polyunsaturated fatty acids (PUFA) contained in walnut (linoleic acid, n-6; linolenic acid, n-3). 相似文献
280.
The ability of grape skins to catalyze in vitro conversion of p-coumaric acid to the more potent antioxidant caffeic acid was studied. Addition of different concentrations of p-coumaric to red grape skins (Cabernet Sauvignon) resulted in formation of caffeic acid. This caffeic acid formation (Y) correlated
positively and linearly to p-coumaric acid consumption (X): Y = 0.5 X + 9.5; R
2 = 0.96, P < 0.0001. The kinetics of caffeic acid formation with time in response to initial p-coumaric acid levels and at different grape skin concentrations, indicated that the grape skins harboured an o-hydroxylation activity, proposedly a monophenol- or a flavonoid 3′-monooxygenase activity (EC 1.14.18.1 or EC 1.14.13.21).
The K
m of this crude o-hydroxylation activity in the red grape skin was 0.5 mM with p-coumaric acid. 相似文献