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1.
1. The ability to achieve optimal camouflage varies between microhabitats in heterogeneous environments, potentially restricting individuals to a single habitat or imposing a compromise on crypsis to match several habitats. However, animals may exhibit morphological and behavioural attributes that enhance crypsis in different habitats. 2. We used an undescribed fish species, Galaxias‘nebula’, to investigate two objectives. First, we examined two potential methods of enhancing crypsis: change in colour pattern and selection of a suitable background. Second, we characterised the colour pattern of this unstudied fish and assessed its capacity for crypsis. 3. No background selection was apparent but the area of dark pigment expressed varied between backgrounds, which may negate the requirement to be choosy about habitats. The capacity to change colour and selection of a background that maximises crypsis are most likely separate, non‐mutually exclusive strategies. 4. Galaxias‘nebula’ exhibits polymorphic, non‐interchangeable colour patterns that have elements of both background pattern matching and disruptive colouration. This, coupled with habitat characteristics, suggests a combination of generalist and specialist strategies of habitat use. The fish’s camouflage strategy and air‐breathing ability may be key to survival under increasing pressure from habitat degradation and invasive predators. 相似文献
2.
《Developmental cell》2021,56(16):2329-2347.e6
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3.
The microbial metabolism of organic matter (OM) in seagrass beds can create sulfidic conditions detrimental to seagrass growth;
iron (Fe) potentially has ameliorating effects through titration of the sulfides and the precipitation of iron-sulfide minerals
into the sediment. In this study, the biogeochemical effects of Fe availability and its interplay with sulfur and OM on sulfide
toxicity, phosphorous (P) availability, seagrass growth and community structure were tested. The availability of Fe and OM
was manipulated in a 2 × 2 factorial experiment arranged in a Latin square, with four replicates per treatment. The treatments
included the addition of Fe, the addition of OM, the addition of both Fe and OM as well as no addition. The experiment was
conducted in an oligotrophic, iron-deficient seagrass bed. Fe had an 84.5% retention efficiency in the sediments with the
concentration of Fe increasing in the seagrass leaves over the course of the experiment. Porewater chemistry was significantly
altered with a dramatic decrease in sulfide levels in Fe addition plots while sulfide levels increased in the OM addition
treatments. Phosphorus increased in seagrass leaves collected in the Fe addition plots. Decreased sulfide stress was evidenced
by heavier δ34S in leaves and rhizomes from plots to which Fe was added. The OM addition negatively affected seagrass growth but increased
P availability; the reduced sulfide stress in Fe added plots resulted in elevated productivity. Fe availability may be an
important determinant of the impact that OM has on seagrass vitality in carbonate sediments vegetated with seagrasses. 相似文献
4.
Splenic gene expression profiling in White Leghorn layer inoculated with the Salmonella enterica serovar Enteritidis
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Salmonella enterica serovar Enteritidis (SE) is a foodborne pathogen that can threaten human health through contaminated poultry products. Live poultry, chicken eggs and meat are primary sources of human salmonellosis. To understand the genetic resistance of egg‐type chickens in response to SE inoculation, global gene expression in the spleen of 20‐week‐old White Leghorn was measured using the Agilent 4 × 44 K chicken microarray at 7 and 14 days following SE inoculation (dpi). Results showed that there were 1363 genes significantly differentially expressed between inoculated and non‐inoculated groups at 7 dpi (I7/N7), of which 682 were up‐regulated and 681 were down‐regulated genes. By contrast, 688 differentially expressed genes were observed at 14 dpi (I14/N14), of which 371 were up‐regulated genes and 317 were down‐regulated genes. There were 33 and 28 immune‐related genes significantly differentially expressed in the comparisons of I7/N7 and I14/N14 respectively. Functional annotation revealed that several Gene Ontology (GO) terms related to immunity were significantly enriched between the inoculated and non‐inoculated groups at 14 dpi but not at 7 dpi, despite a similar number of immune‐related genes identified between I7/N7 and I14/N14. The immune response to SE inoculation changes with different time points following SE inoculation. The complicated interaction between the immune system and metabolism contributes to the immune responses to SE inoculation of egg‐type chickens at 14 dpi at the onset of lay. GC, TNFSF8, CD86, CD274, BLB1 and BLB2 play important roles in response to SE inoculation. The results from this study will deepen the current understanding of the genetic response of the egg‐type chicken to SE inoculation at the onset of egg laying. 相似文献
5.
6.
R. M. Davydov Joanne Smieja S. A. Dikanov Y. Zang Lawrence Que Jr. M. K. Bowman 《Journal of biological inorganic chemistry》1999,4(3):292-301
Radiolytic reduction at 77 K of oxo-/hydroxo-bridged dinuclear iron(III) complexes in frozen solutions forms kinetically
stabilized, mixed-valent species in high yields that model the mixed-valent sites of non-heme, diiron proteins. The mixed-valent
species trapped at 77 K retain ligation geometry similar to the initial diferric clusters. The shapes of the mixed-valent
EPR signals depend strongly on the bridging ligands. Spectra of the Fe(II)OFe(III) species reveal an S=1/2 ground state with small g-anisotropy as characterized by the uniaxial component (g
z
–g
av /2<0.03) observable at temperatures as high as ∼100 K. In contrast, hydroxo-bridged mixed-valent species are characterized
by large g-anisotropy (g
z
–g
av /2>0.03) and are observable only below 30 K. Annealing at higher temperatures causes structural relaxation and changes in
the EPR characteristics. EPR spectral properties allow the oxo- and hydroxo-bridged, mixed-valent diiron centers to be distinguished
from each other and can help characterize the structure of mixed-valent centers in proteins.
Received: 27 June 1998 / Accepted: 25 February 1999 相似文献
7.
ANATH BANDHU DAS ARUP KUMAR MUKHERJEE PREMANANDA DAS 《Botanical journal of the Linnean Society. Linnean Society of London》2001,136(2):221-229
Random amplified polymorphic DNA (RAPD) markers are used to estimate interspecific variation among mangrove and non-mangrove Heritiera fomes, H. littoralis and H. macrophylla. All the species have 2n = 38 chromosomes, with minute structural changes distinguishing the karyotype of each species. Significant variation of 4C DNA content occurs at the interspecific level. Interspecific polymorphism ranged from 14.09% between H. fomes and H. littoralis to 52.73% between H. fomes and H. macrophylla. H. macrophylla showed wide polymorphism in the RAPD marker with H. littoralis (51.23%) and H. fomes (52.73%). Two distinct RAPD products obtained from OPA-10 (1000 bp) and OPD-15 (900 bp) found characteristic molecular markers in H. macrophylla , a species from a non-mangrove habitat. H. macrophylla was more distantly related to H. fomes [genetic distance (1-F) = 0.305] than to H. littoralis [genetic distance (1-F) = 0.273]. H. littoralis was of a closer affinity to H. fomes [genetic distance (1-F) = 0.218] than to H. macrophylla. 相似文献
8.
1. Ship‐induced waves can affect the physical characteristics of lake and river shorelines, and laboratory studies have shown effects on littoral invertebrates. Here, we explored whether these effects could be observed under field conditions along a natural lake shore affected by wave sequences (trains) produced by boats. 2. Individuals of five invertebrate species (Bithynia tentaculata, Calopteryx splendens, Dikerogammarus villosus, Gammarus roeselii, Laccophilus hyalinus) were exposed to waves with increasing shear stress in five habitats differing in structural complexity. 3. Detachment of invertebrates increased with increasing shear stress and was best modelled using sigmoid response curves. Habitat structural complexity mitigated the effects of shear stress, and detachment rate was influenced more by habitat type than by species. A threshold (90% of the individual invertebrates unaffected) stress level of 0.64 N m?2 was found for a structurally complex reed habitat, compared to 0.37 N m?2 for a simple sand habitat. 4. Shear stress associated with wave trains created by recreational boating at a distance of 35 m from the shore and at a speed of 11 km h?1 resulted in 45% detachment of littoral invertebrates. Decreasing the boat‐to‐shore distance to 20 m increased wave shear stress by 30% and invertebrate detachments up to 75%. 5. Disturbance of littoral habitats and invertebrate assemblages are widespread in inland waters used for recreational and/or commercial navigation. Our findings show that the integrity of littoral zones of navigable surface waters could be much improved by implementing management measures such as physically protecting complex habitats with dense reed belts and tree roots, and reducing boat speeds and increasing their minimum shoreline distance. 相似文献
9.
The CD genome species in the genus Oryza are endemic to Latin America, including O. alta, O. grandiglumis and O. latifolia. Origins and phylogenetic relationship of these species have long been in dispute and are still ambiguous due to their homogeneous genome type, similar morphological characteristics and overlapping distribution. In the present study, we sequenced two chloroplast fragments (matK and trnL-trnF) and portions of three nuclear genes (Adh1, Adh2 and GPA1) from sixteen accessions representing seven species with the C, CD, and E genomes, as well as one G genome species as the outgroup. Phylogenetic analyses using parsimony and distance methods strongly supported that the CD genome originated from a single hybridization event, and that the C genome species (O. officinalis or O. rhizomatis instead of O. eichingeri) served as the maternal parent while the E genome species (O. australiensis) was the paternal donor during the formation of CD genome. In addition, the consistent phylogenetic relationships among the CCDD species indicated that significant divergence existed between O. latifolia and the other two (O. alta and O. grandiglumis), which corroborated the suggestion of treating the latter two as a single species or as taxa within species.We thank Tao Sang of Michigan State University (East Lansing, USA) and Bao-rong Lu of Fudan University (Shanghai, China) for their encouragement and assistance. We are also grateful to the International Rice Research Institute (Manila, Philippines) for providing plant material for this study. This research was supported by the Chinese Academy of Sciences (kscxz-sw-101A), the National Natural Science Foundation of China (30025005) and the Program for Key International S & T Cooperation Project of P. R. China (2001CB711103). 相似文献
10.
Wytske de Vries M. I. H. Aleem Anneke Hemrika-Wagner A. H. Stouthamer 《Archives of microbiology》1977,112(3):271-276
Fumarase-free electron particles from Propionibacterium freudenreichii and P. pentosaceum were prepared by discontinuous sucrose gradient centrifugation, and the influence of 2-n-heptyl-4-hydroxy-quinoline-N-oxide (HQNO) and ultraviolet irradiation on the reduction of menaquinone and cytochrome b with l-lactate or glycerol-3-phosphate and the reoxidation by fumarate was studied. In the presence of HQNO the steady state reduction level of menaquinone during fumarate reduction was increased whereas the steady state reduction level of cytochrome b was decreased as compared with the reduction levels measured in the absence of HQNO. The steady state reduction level of menaquinone during electron transport to fumarate was not influenced by ultraviolet irradiation and the steady state reduction level of cytochrome b was decreased at increasing irradiation times. The data indicate that cytochrome b is involved in the electron transport to fumarate.Abbreviations HQNO
2-n-heptyl-4-hydroxyquinoline-N-oxide
- NQNO
2-n-nonyl-4-hydroxyquinoline-N-oxide
Visiting Professor at the Biological Laboratory 相似文献