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Effect of gibberellin on fruit quality and anatomical structure of Hongdeng sweet cherry
No full text研究红灯甜樱桃生长期喷施不同浓度(20、60、100 mg·L~(-1))赤霉素(GA_3)对果实品质及解剖结构的影响。结果表明,60 mg·L~(-1)的GA_3处理增加了单果重与纵径。不同浓度GA_3处理对果实横径无显著影响,但降低了果实硬度、可溶性糖、维生素C和可溶性固形物含量,升高了可滴定酸含量,致果实品质总体下降。解剖结构结果表明,GA_3喷施浓度越大,果实角质层与表皮厚度越薄,果肉细胞与表皮细胞越大,硬度越小。建议在生产中减少GA_3的使用,尤其是高浓度(100 mg·L~(-1))的GA_3喷施对果实不利
Responses of soil respiration to warming vary between growing season and non-growing season in a mountain forest of southwestern China
No full textUnderstanding the temperature sensitivity of soil respiration is very important to quantify the climate-carbon cycle feedback. Most existing studies have only focused on responses of growing-season respiration to warming. Soil respiration of non-growing season may be more sensitive to warming. However, to our knowledge, this hypothesis remains poorly understood. An experiment was conducted in a mountain pine forest of southwestern China to compare the sensitivity of soil respiration to warming (+5 degrees C) between growing and non-growing seasons. Experimental warming decreased soil moisture but increased soil respiration on most of the measuring dates. Warming-caused increase in soil respiration and Q(10) value was greater during the growing season than during the non-growing season. Q(10) values decreased linearly with warming-induced changes in soil moisture. This study provides preliminary evidence that soil respiration of non-growing season is less sensitive to warming compared with that of growing season in the mountain forests experiencing monsoon climate
Assessing the reproductive status of a breeding, translocated female giant panda using data from GPS collar
No full textReintroductions and translocations have proven to be effective measures for rescuing small, isolated populations of endangered wildlife. However, the reproductive status of released wildlife is hard to obtain. To date, a giant panda named Luxin is the only translocated giant panda that has successfully bred in the wild. Using data collected from the GPS collar attached to her, we analysed her activity and home range during a breeding year and compared these values with those collected during a non-breeding (control) year. Delivery and mating days can be identified by extremely low levels of activity or even by the absence of activity. The activity of a giant panda with an infant was low, but it increased gradually after delivery. The activity rates during both the delayed implantation period and the infant-caring period were significantly lower in the breeding year than those in the control year. In the breeding year, the home ranges during the delayed implantation period and pregnancy were larger than those in the control year, while the home range during the infant-caring period was much smaller than that in the control year. Our results suggest that GPS collars embedded with activity sensors can be used to monitor the breeding status of released female giant pandas. They can provide valuable information for decision making in future release projects, providing only small disturbances to released giant pandas
A comprehensive phylogeny of the genus Kurixalus (Rhacophoridae, Anura) sheds light on the geographical range evolution of frilled swamp treefrogs
No full textCurrently, the genus Kurixalus comprises 14 species distributed in Southern, Southeast and East Asia. Because of their relatively low dispersal capability and intolerance of seawater, this group is ideal for the study of terrestrial range evolution, especially that portion of its range that extends into the island archipelagos of Southern Asia. We assembled a large dataset of mitochondrial and nuclear genes, and estimated phylogeny by maximum likelihood and Bayesian methods, and we explored the history of each species via divergence-time estimation based on fossil-calibrations. A variety of ancestral-area reconstruction strategies were employed to estimate past changes of the species' geographical range, and to evaluate the impact of different abiotic barriers on range evolution. We found that frilled swamp treefrogs probably originated in Taiwan or South Vietnam in the Oligocene. Alternatively, the lineage leading to Kurixalus appendiculatus strongly supports a hypothesis of terrestrial connection between the Indian and Asian continents in the Oligocene. The outcome of both our divergence-time estimates and ancestral-area reconstruction suggests that the divergence between species from Indochina and Taiwan can probably be attributed to the opening of the South China Sea, approximately 33 million years ago. We could not find evidence for dispersal between mainland China and Taiwan Island. Formation of both Mekong and Red River valleys did not have any impact on Kurixalus species diversification. However, coincidence in timing of climate change and availability of plausible dispersal routes from the Oligocene to the middle Miocene, plausibly implied that Kurixalus diversification in Asia resulted from contemporaneous, climate-induced environmental upheaval (Late Oligocene Warming at 29 Ma; Mi-1 glaciation since 24.4-21.5 Ma; Mid-Miocene Climatic Optimum at 14 Ma), which alternatively opened and closed dispersal routes
Fecal bacterial diversity of wild Sichuan snub-nosed monkeys (Rhinopithecus roxellana)
No full textThe gastrointestinal tract of primates harbors a complex microbial community, playing an essential role in the degradation of otherwise indigestible structural carbohydrates. The phylogenetic and functional diversity of the bacterial community in the feces as a surrogate for the gastrointestinal tract of wild Sichuan snub-nosed monkeys (Rhinopithecus roxellana, N=6) was characterized based on sequence analysis of 16S rRNA genes. A sex comparison was conducted, with a prior hypothesis that the abundances of the bacterial taxa and/or functional categories associated with energy and nutrient metabolism would be higher in adult females (N=3) due to the higher reproductive costs compared to adult males (N=3). Ten phyla were identified in all samples, among which Bacteroidetes and Firmicutes were the predominant. Included in the above two phyla, the members of Prevotellaceae (Prevotella in particular) and Ruminococcaceae were highly abundant, which are common bacteria in the gastrointestinal tract of primates and can degrade various structural carbohydrates such as cellulose, hemicellulose, and pectin. This functionality was in line with the high abundances of the metagenomes associated with carbohydrate metabolism. Consistent with our hypothesis, the abundances of the metagenomes associated with energy metabolism, folding/sorting and degradation, glycan biosynthesis and metabolism, and metabolism of amino acids were higher in adult females relative to adult males. Sex differences were also detected in the bacterial community structure, although no sex differences in the proportions of any bacterial taxa were found likely due to the small sample size. These results suggested that gastrointestinal bacterial communities may aid adult females in increasing energy and nutrition utilization efficiencies compared to adult males. Fecal bacterial communities were found to be more similar between individuals in adult females than in adult males. Our study presented the first examination of the fecal bacterial diversity of a little-studied, endangered foregut fermenter
Determining threatened species distributions in the face of limited data: Spatial conservation prioritization for the Chinese giant salamander (Andrias davidianus)
No full textThe purpose of this study was to determine whether limited occurrence data for highly threatened species can provide useful spatial information to inform conservation. The study was conducted across central and southern China. We developed a habitat suitability model for the Critically Endangered Chinese giant salamander (Andrias davidianus) based on one biotic and three abiotic parameters from single-site locality records, which represent the only relevant environmental data available for this species. We then validated model quality by testing whether increased percentage of predicted suitable habitat at the county level correlated with independent data on giant salamander presence. We randomly selected 48 counties containing historical records which were distinct from, and independent of, the single-site records used to develop the model, and 47 additional counties containing >50% predicted suitable habitat. We interviewed 2,812 respondents near potential giant salamander habitat across these counties and tested for differences in respondent giant salamander reports between counties selected using each method. Our model predicts that suitable giant salamander habitat is found widely across central and southern China, with counties containing 50% predicted suitable habitat distributed in 13 provinces. Counties with historical records contain significantly more predicted suitable habitat than counties without historical records. There are no statistical differences in any patterns of respondent giant salamander reports in surveyed counties selected from our model compared with the areas of known historical giant salamander distribution. A Chinese giant salamander habitat suitability model with strong predictive power can be derived from the restricted range of environmental variables associated with limited available presence-only occurrence records, constituting a cost-effective strategy to guide spatial allocation of conservation planning. Few reported sightings were recent, however, with most being over 20 years old, so that identification of areas of suitable habitat does not necessarily indicate continued survival of the species at these locations
Does the major aluminium-resistance gene in wheat, TaALMT1, also confer tolerance to alkaline soils?
No full textA major limitation to plant growth in acid soils is the prevalence of toxic Al3+. Most genotypic variation for acid soil-tolerance in wheat is linked with the Al3+-activated efflux of malate anions from roots which is controlled by TaALMT1 on chromosome 4DL. Recent studies have also linked TaALMT1 with tolerance to high pH solutions and alkaline soils. This study tested the hypothesis that an Al3+-resistant allele of TaALMT1 also confers tolerance to alkaline conditions. The near-isogenic wheat lines, ET8 (Al3+-resistant) and ES8 (Al3+-sensitive), have different alleles of the TaALMT1 gene and contrasting resistance to Al3+ toxicity. Growth of these lines was compared in acid and alkaline soils with contrasting mineralogy and in a range of high pH hydroponic solutions of varying composition. No consistent differences in root or shoot growth were detected between the lines in the alkaline soils or in the high pH hydroponic treatments. Malate efflux was detected from ET8 in acidic solution with Al3+ but no substantial malate efflux was detected at pH 9.0 treatment with added Na2SO4. The results are inconsistent with the hypothesis that the TaALMT1 gene confers an advantage to wheat on alkaline soils
Habitat orientation alters the outcome of interspecific competition: A microcosm study with zooplankton grazers
No full textHabitat orientation has recently been demonstrated to affect the foraging behavior, growth, and production of plankton grazers. Because the orientation effect may vary with species, we hypothesize that habitat orientation may alter interspecific interactions between animal species. We experimentally investigated how habitat orientation (placing cuboid chambers in three orientations with long, medium, and small side as the chamber height) affected the interaction between two common cladoceran species, Daphnia magna and Moina micrura, which competitively exploited green algae of Chlorella pyrenoidosa at two volume scales (64 and 512ml). Results show that chamber orientation and volume additively affected the behavior and species performance of the grazers. Specifically, both grazer species generally decreased their average swimming velocity, grazing rate (on algal cells), body size, and survival and reproduction rates with increasing chamber height for both chamber volumes and with decreasing chamber volume regardless of chamber orientation. Nevertheless, the decrease magnitude was greater for M.micrura with increasing chamber height but was greater for D.magna with decreasing chamber volume. Correspondingly, when cocultured, the density ratio of D.magna to M.micrura increased with increasing chamber height but decreased with decreasing chamber volume. At the end of the experiment, none of D.magna individuals survived in the small and short (large-based) chambers, and few M.micrura individuals survived in large and tall (small-based) chambers. These results indicate that both habitat orientation and size affect the outcome of interspecific competition between grazer species. We suggest that variation in habitat orientation may improve community coexistence and species diversity in nature
Available forms of nutrients and heavy metals control the distribution of microbial phospholipid fatty acids in sediments of the Three Gorges Reservoir, China
No full textThe construction of the Three Gorges Reservoir (TGR) as well as the development of local industry and agriculture not only had tremendous impacts on the environment but also affected human health. Although water, soil, and air in the TGR have been well studied for environmental risk assessment, very little information is available on benthic sediments and microorganisms. In this study, sedimentary samples were collected along the main stream of the TGR to examine microbial phospholipid fatty acids (PLFA) and relevant variables (e.g., nutrients and heavy metals) after the full operation of the TGR. The results showed that there were prominent trends (increase or decrease) of sedimentary PLFAs and properties from downstream to upstream. Bacteria-specific PLFA decreased toward the dam, while fungi-specific PLFA did not show any significant trend. The PLFA ratio of fungi to bacteria (F/B) increased along the mainstream. The total PLFA concentration, which represents the microbial biomass, decreased significantly toward the dam. Upstream and downstream sampling points were clearly distinguished by PLFA ordination in the redundancy analysis (RDA). That finding showed microbial PLFAs to have an obvious distribution pattern (increase or decrease) in the TGR. The PLFA distribution was markedly controlled by nutrients and heavy metals, but nutrients were more important. Moreover, among nutrients, Bio-P, NH4 (+)-N, NO3 (-)-N, and DOC were more important than TP, TN, TOC, and pH in controlling PLFA distribution. For heavy metals, Tl, V, Mo, and Ni were more important than Zn, Cu, Cd, and Pb. These findings suggested that Tl, V, Mo, and Ni should not be ignored to guard against their pollution in the TGR, and we should pay attention to them and make them our first priority. This study highlighted that the construction of the TGR changed riverine environments and altered microbial communities in sediments by affecting sedimentary properties. It is a reminder that the microbial ecology of sediment as an indicator should be considered in assessing the eco-risk of the TGR
Function of Lactate Dehydrogenase in Cardiac and Skeletal Muscle of Phrynocephalus Lizard in Relation to High-Altitude Adaptation
Get PDFPoikilothermic animals living in high-altitude environments can be greatly affected by the anaerobic metabolism and lactate recycling, which are catalyzed by an enzyme called lactate dehydrogenase (LDH). However, the function and possible regulatory mechanisms of their anaerobic glycolysis remained elusive. We compared the difference in LDH between a native high-altitude (4 353 m) lizard, Phrynocephalus erythrurus, and a closely related species, Phrynocephalus przewalskii that lives in intermediate altitude environment (1 400 m). The activity of LDH, the concentration of lactate, the distribution of isoenzyme, and the mRNA amounts of Ldh-A and Ldh-B were determined. In cardiac muscle, the lactate-forming activity of P. erythrurus in LDH was higher than of P. przewalskii LDH at all three temperatures tested (10 °C, 25 °C and 35 °C), while lactate-oxidation activity of LDH was significantly different between the two species only at 25 °C and 35 °C. In skeletal muscle, both lactate-forming and lactate-oxidation rates of P. erythrurus were lower than that of P. przewalskii. There was a higher proportion of H subunit and a significantly higher expression of Ldh-B, with a concomitant decrease of lactate concentration in P. erythrurus. These results indicate that P. erythrurus may have a strong potential for anaerobic metabolism, which is likely adapted to the hypoxic environment at high altitudes. Furthermore, P. erythrurus is capable of oxidizing more lactate than P. przewalskii. The Ldh-A cDNA of the two species consists of a 999 bp open reading frame (ORF), which encodes 332 amino acids, while Ldh-B cDNA consists of a 1 002 bp ORF encoding 333 amino acids. LDHA has the same amino acid sequence between the two species,
but three amino acid substitutions (V12I, N21S and N318K) were observed in LDHB. Structure analysis of LDH indicated that the substitutions of residues Val12 and Asp21 in P. erythrurus could be responsible for the high-altitude adaptation. The LDH characteristics of LDH in P. erythrurus suggest unique adaptation strategies of anaerobic metabolism in hypoxia and cold environments at high altitudes for poikilothermic animals