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921.
Evolutionary systematics and biogeography of the arid habitat‐adapted rodent genus Gerbillus (Rodentia,Muridae): a mostly Plio‐Pleistocene African history
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Arame Ndiaye Pascale Chevret Gauthier Dobigny Laurent Granjon 《Journal of Zoological Systematics and Evolutionary Research》2016,54(4):299-317
The systematics of the arid‐adapted Old World Gerbillus rodent genus has always been challenging, with many different taxonomic arrangements proposed. Beyond such taxonomic aspects, the timing and geographical pattern of the evolutionary history of this group remains largely unknown. Based on mitochondrial (cytochrome b) and nuclear (interphotoreceptor retinoid‐binding protein) sequences obtained from the specimens of 21 species, we conducted a phylogenetic analysis of the group, estimated the ages and putative ancestral ranges of its major lineages. Four major clades were clearly retrieved within Gerbillus, for which we propose a subgenus rank. We showed that the emergence of the genus dates back to the end of the Miocene, which corresponds to a period of aridification and C4 vegetation expansion in open habitats, while the four sublineages originated at the end of the Pliocene. Most subsequent diversification events occurred during the Pleistocene, a period characterized by recurrent climatic/environmental shifts with increasing aridification during the last two millions of years. Finally, we suggested that most of the Gerbillus evolutionary history took place in Africa. Only in a few instances did dispersal events from Africa to Asia give birth to extant Asian lineages, a pattern that contrasts with what has been found in many animal groups. 相似文献
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Knox and Parson have objected to our previous conclusion on possible negative entropy production during primary photochemistry, i.e., from photon absorption to primary charge separation, by considering a pigment system in which primary photochemistry is not specifically considered. This approach does not address our proposal. They suggest that when a pigment absorbs light and passes to an excited state, its entropy increases by hν/T. This point is discussed in two ways: (i) from considerations based on the energy gap law for excited state relaxation; (ii) using classical thermodynamics, in which free energy is introduced into the pigment (antenna) system by photon absorption. Both approaches lead us to conclude that the excited state and the ground state are isoentropic, in disagreement with Knox and Parson. A discussion on total entropy changes specifically during the charge separation process itself indicates that this process may be almost isoentropic and thus our conclusions on possible negentropy production associated with the sequence of reactions which go from light absorption to the first primary charge separation event, due to its very high thermodynamic efficiency, remain unchanged. 相似文献
926.
Photoautotrophic shoot and root development for triploid melon 总被引:2,自引:0,他引:2
Adelberg Jeffrey Fujiwara Kazuhiro Kirdmanee Chalermpol Kozai Toyoki 《Plant Cell, Tissue and Organ Culture》1999,57(2):95-104
The aim of this investigation was to establish environmental factors which promote growth and photosynthesis of melon (Cucumis
melo L.) shoot buds, in vitro, and determine if photoautotrophic shoots had superior root forming ability in photoautotrophic
environments. Buds from the triploid melon clone ‘(L-14×B)×L-14’ were observed for 21 days after transfer from a multiplication
MS medium with 3% sucrose and 10 μM benzyladenine (BA) to a shoot development medium with 1 μM BA at three levels of sucrose
in the medium (0, 1 and 3%), and light (50, 100 and 150 PPF) and CO2 (500, 1000 and 1500 ppm) in the culture chamber. More shoot buds were observed with 3% sucrose in the medium. Increased light
and CO2 had a positive interaction with shoot proliferation. Fresh and dry weights were greatest at 3% sucrose, 150 PPF light and
1500 ppm CO2. Shoot buds grew more slowly in sugar-free medium, but fresh and dry weight still doubled over 21 days of culture. Net photosynthetic
rates (NPR) of buds were negative after four days in treatment conditions, but became positive after transfer to fresh, sugar-free
medium. Two triploid genotypes of melon were (1) grown in vitro with sugar (photomixotrophic) and without sugar (photoautotrophic),
(2) rooted in sugar-free media, both in a laboratory controlled environment chamber (in vitro) and a greenhouse acclimatization
unit (ex vitro), and (3) compared for subsequent nursery growth in the greenhouse unit. The genotype ‘(L-14×B)×L-14’ produced
more shoots than ‘(L-14×B)×Mainstream’ in both photomixotrophic or photoautotrophic conditions. ‘(L-14×B)×L-14’ rooted as
well from either photoautotrophic and photomixotrophic shoots but ‘(L-14×B)×Mainstream’ rooted less frequently from photoautotrophic
shoots. Seventy-six percent of the shoots in the laboratory controlled environment chamber were able to root photoautotrophically,
whereas 47% of the shoots in the greenhouse acclimatization unit were rooted. Between 77% and 88% of plantlets from all treatment
combinations survived transfer to the nursery. After growth in the nursery, the sizes of plants (fresh weight, dry weight,
leaf area) were the same for either genotype, from either photoautotrophic or photomixotrophic shoots. Nursery plants that
had been rooted in the laboratory controlled environment chamber were larger than those rooted in the acclimatization greenhouse
chamber.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
927.
Zulina Zakaria Mohd Nasir Hassan Muhamad Awang 《The International Journal of Life Cycle Assessment》1999,4(4):191-194
Conclusion In conclusion, LCA that is conducted and used appropriately is an indispensable tool to assist decision-makers in making an
informed decision about the environmental impacts of their activities, products or services. A global effort towards LCA use
should be encouraged and countries in the Asian/Pacific Regions should not be left out. LCA-related activities reported in
the symposium were described 相似文献
928.
Advances in computer technology and applied statistics have provided the opportunity for the non-statistician to investigate uncertainty in a quantitative manner. The following discussion argues, notwithstanding the possible misuse of uncertainty analysis, that uncertainty is always present and that decisions based on human or ecological risk assessment would benefit from disclosure of uncertainty in the estimated risks. 相似文献
929.
Market Failure and the Environmental Policies of Firms: Economic Rationales for "Beyond Compliance" Behavior 总被引:4,自引:0,他引:4
Forest Reinhardt 《Journal of Industrial Ecology》1999,3(1):9-21
This paper is an inquiry into the circumstances under which the voluntary provision of environmental public goods might be sensible from a firm's point of view. If environmental externalities were the only departure from the economic assumptions of perfect competition, and if no firms had preferential access to superior (low-cost) stocks of natural resources, firms that volunteered to internalize costs could not survive. But because externalities coexist with other departures from the competitive paradigm, such as asymmetric information and oligopoly competition, firms may find it in their shareholders' interests to provide environmental public goods to a greater degree than required by law. A number of firms, especially in Europe and North America, assert that they are pursuing "beyond-compliance" environmental policies. From the perspective of a firm's shareholders, it makes sense to pursue such policies if they increase the firm's expected value or if they appropriately manage business risk.
This paper discusses economically rational explanations for such policies. It analyzes the ways in which a firm's chances of financial success in pursuing any one of them are influenced by the firm's market position and organizational capabilities and by the basic structure of the industry in which it competes. 相似文献
This paper discusses economically rational explanations for such policies. It analyzes the ways in which a firm's chances of financial success in pursuing any one of them are influenced by the firm's market position and organizational capabilities and by the basic structure of the industry in which it competes. 相似文献
930.
Safety Evaluation of Transgenic Tilapia with Accelerated Growth 总被引:2,自引:0,他引:2
Isabel Guillén Jorge Berlanga Carmen M. Valenzuela Antonio Morales José Toledo Mario P. Estrada Pedro Puentes Orlando Hayes José de la Fuente 《Marine biotechnology (New York, N.Y.)》1999,1(1):2-14
Recent advances in modern marine biotechnology have permitted the generation of new strains of economically important fish
species through the transfer of growth hormone genes. These transgenic fish strains show improved growth performance and therefore
constitute a better alternative for aquaculture programs. Recently, we have obtained a transgenic tilapia line with accelerated
growth. However, before introducing this line into Cuban aquaculture, environmental and food safety assessment was required
by national authorities. Experiments were performed to evaluate the behavior of transgenic tilapia in comparison to wild tilapia
as a way to assess the environmental impact of introducing transgenic tilapia into Cuban aquaculture. Studies were also conducted
to evaluate, according to the principle of substantial equivalence, the safety of consuming transgenic tilapia as food. Behavior
studies showed that transgenic tilapia had a lower feeding motivation and dominance status than controls. Food safety assessment
indicated that tilapia growth hormone has no biological activity when administered to nonhuman primates. Furthermore, no effects
were detected in human healthy volunteers after the consumption of transgenic tilapia. These results showed, at least under
the conditions found in Cuba, no environmental implications for the introduction of this transgenic tilapia line and the safety
in the consumption of tiGH-transgenic tilapia as an alternative feeding source for humans. These results support the culture
and consumption of these transgenic tilapia.
Received: March 9, 1998; accepted June 25, 1998. 相似文献