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Luke L. M. Heaton Eduardo López Philip K. Maini Mark D. Fricker Nick S. Jones 《Proceedings. Biological sciences / The Royal Society》2010,277(1698):3265-3274
Cord-forming fungi form extensive networks that continuously adapt to maintain an efficient transport system. As osmotically driven water uptake is often distal from the tips, and aqueous fluids are incompressible, we propose that growth induces mass flows across the mycelium, whether or not there are intrahyphal concentration gradients. We imaged the temporal evolution of networks formed by Phanerochaete velutina, and at each stage calculated the unique set of currents that account for the observed changes in cord volume, while minimizing the work required to overcome viscous drag. Predicted speeds were in reasonable agreement with experimental data, and the pressure gradients needed to produce these flows are small. Furthermore, cords that were predicted to carry fast-moving or large currents were significantly more likely to increase in size than cords with slow-moving or small currents. The incompressibility of the fluids within fungi means there is a rapid global response to local fluid movements. Hence velocity of fluid flow is a local signal that conveys quasi-global information about the role of a cord within the mycelium. We suggest that fluid incompressibility and the coupling of growth and mass flow are critical physical features that enable the development of efficient, adaptive biological transport networks. 相似文献
3.
Eduardo J. Delgado 《Journal of molecular modeling》2010,16(8):1421-1425
Despite their importance as herbicides, dimethoxypyrimidinylsalicylic acids has been poorly characterized from a physical-chemical
point of view. This lack of information has prevented the assessment of their impact in the environment once they are released.
In this study, environmentally important properties (free energy of solvation, Henry’s law constant, octanol/air, and octanol/water
partition coefficients) of 39 dimethoxypyrimidinylsalicylic derived compounds are calculated by density functional theory
(DFT) methods at B3LYP/6-31G(d,p) level of theory using the Poisson-Boltzmann solvation model. These properties have not been
reported previously for this family of compounds, neither experimentally or theoretically. 相似文献
4.
Capuchin monkeys (Sapajus spp.) in captive settings frequently manipulate and throw objects. In the wild, they may push or drop stones and sticks toward targets during inter- or intraspecific threat displays. In addition, female capuchin monkeys exhibit a broad repertoire of behaviors during their proceptive period, including facial expressions, vocalizations, stereotyped body postures, and touch-and-run behavior. This study reports stone throwing as a newly-described communicative behavior during the proceptive display of females in a group of bearded capuchin monkeys (S. libidinosus) in Serra da Capivara National Park, Brazil. During a two-year study, three females from one group were seen throwing stones at males during their proceptive phase. After this period, three other females in the same group exhibited the same behavior. Although it may be possible that this pattern is the result of several independent innovations by each female, the apparent absence of this behavior in other groups leads us to suggest that we have documented the diffusion of a new behavioral trait or tradition within this capuchin social group. 相似文献
5.
Eduardo León-Ruiz Purificación Alcázar Eugenio Domínguez-Vilches Carmen Galán 《Aerobiologia》2011,27(1):37-50
The present study sought to determine which of the common Poaceae species in the study area contribute most to the Poaceae
pollen season curve, and to determine the phenological behaviour of the species studied. The different floral phenophases
in thirty-three Poaceae species common in and around the city of Córdoba (SW Iberian Peninsula) were checked periodically
over the period 2004–2006. Results showed that longer phenological ranges were recorded in the coolest and wettest year, and
shorter ranges in the warmest and driest year. Moreover, ranges varied as a function of altitude: populations in lower-lying
areas flowered earlier than those at higher altitudes. The results, taken in conjunction with the findings of preliminary
research into potential pollen production, showed that probably only four of the Poaceae species studied—Dactylis glomerata, Lolium rigidum, Trisetaria panicea and Vulpia geniculata—were major contributors to the Poaceae airborne pollen curve. 相似文献
6.
Carbonic anhydrase subunits of the mitochondrial NADH dehydrogenase complex (complex I) in plants 总被引:2,自引:0,他引:2
The mitochondrial nicotinamide adenine dinucleotide, reduced (NADH) dehydrogenase complex (complex I) of plants has a molecular mass of about 1000 kDa and is composed of more than 40 distinct protein subunits. About three quarter of these subunits are homologous to complex I subunits of heterotrophic eukaryotes, whereas the remaining subunits are unique to plants. Among them are three to five structurally related proteins that resemble an archaebacterial γ-type carbonic anhydrase (γCA). The γCA subunits are attached to the membrane arm of complex I on the matrix-exposed side and form an extra spherical domain. At the same time, they span the inner mitochondrial membrane and are essential for assembly of the protein complex. Expression of the genes encoding γCA subunits is reduced if plants are cultivated in the presence of elevated CO2 concentration. The functional role of these subunits within plant mitochondria is currently unknown but might be related to photorespiration. We propose that the complex I–integrated γCAs are involved in mitochondrial HCO3 − formation to allow efficient recycling of inorganic carbon for CO2 fixation in chloroplasts under high light conditions. 相似文献
7.
Chromosomes of Prorocentrum triestinum and P. micans have similar substructural and morphometrical values as revealed by electron microscopy of thin sections. However, differences were found between the species in mean length, volume and numerical density of chromosomes, and the volume of the chromosome complement, the nuclear volume and the chromosome number. When examined by a whole-mount procedure both Prorocentrum species have left-handed screw-like chromosomes which end in differentiated telomeres. The chromosomes divide sequentially from one telomere towards the other, presenting a Y and finally a V configuration. At the region where each chromosome divides nascent sister chromatids are connected by two bridges. Sister chromatids have similar quantitative values when compared with each other and with the still undivided chromosome, which suggests that both replication and division take place as coupled events.Supported by CAICYT, grant 2409/83 相似文献
8.
José L. Caballero Eduardo Martinez Francisco Malpartida David A. Hopwood 《Molecular & general genetics : MGG》1991,230(3):401-412
Summary Sequence analysis of the actVA region of the actinorhodin biosynthetic gene cluster of Streptomyces coelicolor revealed a succession of six open reading frames (ORFs), all running in the same direction and extending over 5.32 kb. The protein product of actVA-ORF1 strongly resembles that of another gene, elsewhere in the act cluster (actII-ORF2), which codes for a trans-membrane protein previously implicated in actinorhodin export from the mycelium. This suggests that the two gene products may co-operate in actinorhodin export, perhaps being sufficient for self-protection of the organism against suicide. At least four of the other five ORFs are implicated in the control of the C-6 and C-8 ring-hydroxylation reactions, lacking in actVA mutants, that occur at middle to late stages in the actinorhodin biosynthetic pathway. This conclusion was reached by genetic mapping of actVA mutants to actVA-ORF3 and-ORF5 (and perhaps -ORF4), and by the finding of strong resemblances between the protein products of actVA-ORF2 and -ORF6 and the products of genes of the oxytetracycline or tetracenomycin gene clusters that have been implicated in ring-hydroxylation reactions in the biosynthesis of these other aromatic polyketide antibiotics. 相似文献
9.
The effect of cyclosporine on PMA-stimulated superoxide production has been studied on human alveolar macrophages, human neutrophils, cytoplasts and Epstein-Barr-virus-transformed B lymphocytes. Cyclosporine inhibits superoxide production in alveolar macrophages but not in neutrophils and cytoplasts. The respiratory burst of B-lymphocytes was scarcely inhibited by cyclosporine. The activity of NADPH oxidase from macrophages and neutrophils was not directly affected by cyclosporine. These data are considered in relation with the proposed mechanism for cyclosporine action and the stimulation of the respiratory burst. 相似文献
10.
Hormonal changes associated with fruit set and development in mandarins differing in their parthenocarpic ability 总被引:2,自引:0,他引:2
Satsuma [Citrus unshiu (Mak) Marc.] and Clementine [Citrus reticulata (Hort.) Ex. Tanaka, cv. Oroval] are two related species of seedless mandarins which differ in their tendency to set parthenocarpic fruits. Satsuma fruits naturally set parthenocarpically whereas Clementine mandarins show very low ability to set fruit in the absence of cross-pollination. The endogenous levels of gibberellins (GAs) and free and conjugated indole-acetic acid (IAA) and abscisic acid (ABA) throughout early stages of fruit development were investigated in seedless cultivars of both species. Analyses performed by full-scan combined gas chromatography-mass spectrometry (GC-MS) of extracts from ovaries at anthesis demonstrated the presence of GA19, GA20, GA29, GA1, GA8, GA3 and iso-GA3 in Satsuma mandarin, whereas only GA29, GA3 and trace levels of GA8 were detected in Clementine. At this developmental stage GA-like substances, as estimated by bioassay, reached their highest levels in Satsuma, while Clementine mandarins contained relatively lower levels. In both species the highest levels of free IAA were found at petal-fall stage at which time free ABA levels also peaked. Developing fruits of Clementine had higher amounts of both free IAA and ABA. In Satsuma, levels of conjugated IAA remained low throughout reproductive development whereas in Clementine they increased as the free form declined. In contrast, conjugated ABA was at low levels in Clementine but reached higher concentrations in Satsuma. These results suggest that in these mandarins the potential for setting parthenocarpic fruits is mainly influenced by the hormonal status of the fruit during the later stages of cell division and early stages of cell enlargement. Thus, the condition of low ability to set parthenocarpic fruits appears to be associated with lower levels of active GAs, lower capability to catabolize ABA to conjugated ABA and higher ability to conjugate IAA during this period. 相似文献