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1.
Many species of the butterfly genus Phengaris are regarded as endangered in many parts of their distribution. Several species are also widely distributed across northern China. Due to land use change and overgrazing, their habitats are declining and many patches have been lost. This paper investigates the distribution and habitats of the Chinese Phengaris species (of the subgenus Maculinea). Shrub-grassland near forests seem the most frequent habitat for Phengaris, while flat open grasslands are mostly over-grazed and thus survival for Phengaris butterflies there seems difficult. Throughout Europe, P. teleius is an endangered species, while there is still no information on its status in China. To improve the knowledge on the population ecology of P. teleius, its population structure, adult behaviour and movement were studied through mark–release–recapture methods in the Qinling Mountains of Taibai County. Eight grassland patches which were potentially suitable were found in the area in 2013. In total, 480 individuals (274 females) were marked, resulting in an overall recapture rate of 16 %. The average daily population size was 44 butterflies (±23 SD) during the adult flight period. Sixty-seven percent of the females and 38 % of the males moved less than 50 m, and 17 % of recaptured females and 38 % of males moved more than 200 m. The mean movement distance was 107 ± 177 m for males and 182 ± 122 m for females. The majority of the recaptures (86 %) were made within the patches, only a few individuals (14 %) moved between patches. Due to human disturbance and destruction, all of the eight potentially suitable patches are becoming smaller and increasingly isolated, thus these populations of P. teleius may face an increasing risk of extinction, which may well be a tip of the iceberg of habitat loss and fragmentation of P. teleius in Taibai County and possibly beyond. Hence we hope our initial study of P. teleius could have positive impacts on the conservation of Phengaris butterflies in China.  相似文献   

2.
Although many fish species are known to feed on jellyfish, only a few quantitative studies on this subject have been conducted in the field or laboratory. We combined field observations and feeding experiments to quantitatively evaluate the potential feeding capability of the black scraper Thamnaconus modestus on giant jellyfish Nemopilema nomurai in a jellyfish-abundant area. Underwater observations revealed that shoals of T. modestus fed voraciously on jellyfish when the jellyfish were close to the fish’s seaweed habitat. Gut contents of field-collected T. modestus almost exclusively consisted of jellyfish. In tank trials, feeding activity of black scraper was high when light intensity was between about 1.1 lx and 50 × 103 lx. The estimated feeding speed of T. modestus on the jellyfish in the Sea of Japan when the jellyfish bloom occurred was 10.0 ± 2.0 times fish body weight per day. The results support the prediction that T. modestus and probably other coastal medusivorous fishes have a substantial capability to eliminate jellyfish blooms. Considering that they are highly dependent on seaweed bed, protection of such habitats for these medusivores may be the most cost-efficient control method for jellyfish blooms.  相似文献   

3.
There is considerable global interest in rebuilding depleted populations of sea cucumbers (Echinodermata, Holothuroidea) to address conservation and economic goals. For the vast majority of holothurian species, the habitat and food requirements of the juvenile stage are poorly understood. We investigated the distribution and microhabitat associations of juveniles of a commercially important sea cucumber, Stichopus cf. horrens, in the shallow, shoreward side of a coral reef (or backreef) in northern Philippines (16°21′38.7″N, 119°59′47.9″E). Relationships between juvenile density and the physical, chemical and biological characteristics of their habitat were examined. Potential food sources of the juveniles were also investigated using elemental and stable isotope analysis. Results showed that juveniles are more abundant in seagrass areas and the transition zone between seagrass and the rubble-dominated reef flat. A non-metric multidimensional scaling (MDS) plot indicated that juvenile density was most positively associated with coarser sand and rubble (>0.5 mm) and seagrass (Thalassia hemprichii) abundance (2D stress = 0.11). Juvenile density was also positively associated with sediment organic matter from plant detritus to a lesser extent. Elemental and isotope analysis of one site indicated that epiphytes were the primary food source of juveniles, while sediment detritus from microalgae and seagrass was a secondary food source. This study corroborates anecdotal evidence regarding the importance of seagrass to S. cf. horrens as potential refugia and source of high-quality food for its juveniles. These findings underscore the need to protect the nursery habitats of wild juveniles and provide critical information for the selection of suitable natural habitats for releasing cultured juveniles of this important species.  相似文献   

4.
The green-algal class Klebsormidiophyceae (Streptophyta), which occurs worldwide, comprises the genera Klebsormidium, Interfilum, Entransia, and Hormidiella. Ecophysiological research has so far focused on the first two genera because they are abundant in biological soil crust communities. The present study investigated the photosynthetic performances of Hormidiella attenuata and two strains of Entransia fimbriata under light, temperature, and desiccation stress. Their ultrastructure was compared using transmission electron microscopy. The two Entransia strains showed similar physiological responses. They used light more efficiently than Hormidiella, as indicated by higher oxygen production and relative electron transport rate under low light conditions, lower light saturation and compensation points, and higher maximum oxygen production during light saturation. Their requirement for low light levels explains the restriction of Entransia to dim limnetic habitats. In contrast, Hormidiella, which prefers drier soil habitats, responded to light gradients similarly to other aero-terrestrial green algae. Compared to Entransia, Hormidiella was less affected by short-term desiccation, and rehydration allowed full recovery of the photosynthetic performance. Nevertheless, both strains of Entransia coped with low water availability better than other freshwater algae. Photosynthetic oxygen production in relation to respiratory consumption was higher in low temperatures (Entransia: 5 °C, Hormidiella: 10 °C) and the ratio decreased with increasing temperatures. Hormidiella exhibited conspicuous triangular spaces in the cell wall corners, which were filled either with undulating cell wall material or with various inclusions. These structures are commonly seen in various members of Klebsormidiophyceae. The data revealed significant differences between Hormidiella and Entransia, but appropriate adaptations to their respective habitats.  相似文献   

5.
Macrocystis integrifolia and Lessonia trabeculata form vast kelp beds providing a three-dimensional habitat for a diverse invertebrate and fish fauna off northern Chile. Habitat modifications caused by the El Niño Southern Oscillation (ENSO) are likely to alter the inhabiting communities. The aim of this study was to reveal relationships between distinct habitat structures of a M. integrifolia kelp bed, a dense L. trabeculata kelp bed and L. trabeculata patches colonizing a barren ground, and the associated dominant macrobenthic key species. Seasonally 15 sampling units (10 m2 each) of any of the three habitats were monitored by SCUBA divers, which counted sporophytes and macroinvertebrates living between the latter. Furthermore, samples of plants were analysed in the laboratory to measure the morphological variables: total plant length, maximal holdfast diameter, stipe number, number of dichotomies per stipe, frond width and total drained wet mass. Multivariate analysis showed that the L. trabeculata kelp bed is denser, with a higher number of dichotomies per stipe, whereas sporophytes of M. integrifolia are longer with more stipes and wider fronds. Sporophytes of L. trabeculata patchily present on barren ground are shorter and have more stipes compared with those in the dense L. trabeculata kelp bed. Thus, the habitats provide different three-dimensional structures. The associated macrobenthic communities show a variable degree of overlapping; however, key faunal assemblages were distinguished for each habitat. Our study provides evidence that habitat diversity drives species diversity, the more homogeneous, monospecifically composed kelp bed habitats show comparatively low diversity, mainly caused by the dominance of the ascidian P. chilensis and T. tridentata in the M. integrifolia bed, and the mussel A. ater only present in the L. trabeculata bed. Species richness and diversity is highest in the heterogeneous habitat where L. trabeculata patches interrupt the barren ground. Our study revealed morphological differences between M. integrifolia and L. trabeculata kelp beds reflected in stipe number, plant length, dichotomies per stipe, and wet mass, which influence the composition of the associated characteristic fauna and its functional relations i.e. T. niger and T. tridentata.  相似文献   

6.

Objective

To improve the production of trans-10,cis-12-conjugated linoleic acid (t10,c12-CLA) from linoleic acid in recombinant Yarrowia lipolytica.

Results

Cells of the yeast were permeabilized by freeze/thawing. The optimal conditions for t10,c12-CLA production by the permeabilized cells were at 28 °C, pH 7, 200 rpm with 1.5 g sodium acetate l?1, 100 g wet cells l?1, and 25 g LA l?1. Under these conditions, the permeabilized cells produced 15.6 g t10,c12-CLA l?1 after 40 h, with a conversion yield of 62 %. The permeabilized cells could be used repeatedly for three cycles, with the t10,c12-CLA extracellular production remaining above 10 g l?1.

Conclusion

Synthesis of t10,c12-CLA was achieved using a novel method, and the production reported in this work is the highest value reported to date.
  相似文献   

7.
In addition to the already known cagA gene, novel genetic markers have been associated with Helicobacter pylori (H. pylori) virulence: the dupA and vacAi genes. These genes might play an important role as specific markers to determine the clinical outcome of the disease, especially the vacAi gene, which has been expected to be a good marker of severe pathologies like gastric adenocarcinoma. In the present study, the association of cagA, dupA, and vacAi genes with gastroduodenal pathologies in Chilean patients was studied. One hundred and thirty-two patients positive for H. pylori were divided into two groups—non-severe and severe gastric pathologies—and investigated for the presence of cagA, dupA, and vacAi H. pylori virulence genes by PCR. The cagA gene was detected in 20/132 patients (15.2%), the vacAi1 gene was detected in 54/132 patients (40.9%), the vacAi2 gene was detected in 26/132 patients (19.7%), and the dupA gene was detected in 50/132 (37.9%) patients. Logistic regression model analysis showed that the vacAi1 isoform gene in the infected strains and the severity of the diseases outcome were highly associated, causing severe gastric damage that may lead to gastric cancer (p < 0.0001; OR = 8.75; 95% CI 3.54–21.64). Conversely, cagA (p = 0.3507; OR = 1.62; 95% CI 0.59–4.45) and vacAi2 (p = 0.0114; OR = 3.09; 95% CI 1.26–7.60) genes were not associated with damage, while the dupA gene was associated significantly with non-severe clinical outcome (p = 0.0032; OR = 0.25; 95% CI 0.09–0.65). In addition, dupA gene exerts protection against severe gastric pathologies induced by vacAi1 by delaying the outcome of the disease by approximately 20 years.  相似文献   

8.
The seaweed genus Gracilaria is a potential candidate for the production of bioethanol due to its high carbohydrate content. Gracilaria is abundant throughout the world and can be found in both wild and cultivated forms. Differences in the ecological factors such as temperature, salinity, and light intensity affecting wild and cultivated specimens may influence the biochemical content of seaweeds, including the carbohydrate content. This study aimed to investigate the proximate composition and potential bioethanol production of wild and cultivated G. gigas and G. verrucosa. Bioethanol was produced using separate hydrolysis fermentation (SHF), employing a combination of enzymatic and acid hydrolysis, followed by fermentation with Saccharomyces cerevisiae ATCC 200062. The highest carbohydrate content was found in wild G. gigas. The highest galactose and glucose contents (20.21 ± 0.32 and 9.70 ± 0.49 g L?1, respectively), as well as the highest production of bioethanol (3.56 ± 0.02 g L?1), were also found in wild G. gigas. Thus, we conclude that wild G. gigas is the most promising candidate for bioethanol production. Further research is needed to optimize bioethanol production from wild G. gigas. Domestication of wild G. gigas is a promising challenge for aquaculture to avoid overexploitation of this wild seaweed resource.  相似文献   

9.
10.
We previously demonstrated efficient transformation of the thermophile Geobacillus kaustophilus HTA426 using conjugative plasmid transfer from Escherichia coli BR408. To evaluate the versatility of this approach to thermophile transformation, this study examined genetic transformation of various thermophilic Bacillus and Geobacillus spp. using conjugative plasmid transfer from E. coli strains. E. coli BR408 successfully transferred the E. coliGeobacillus shuttle plasmid pUCG18T to 16 of 18 thermophiles with transformation efficiencies between 4.1 × 10?7 and 3.8 × 10?2/recipient. Other E. coli strains that are different from E. coli BR408 in intracellular DNA methylation also generated transformants from 9 to 15 of the 18 thermophiles, including one that E. coli BR408 could not transform, although the transformation efficiencies of these strains were generally lower than those of E. coli BR408. The conjugation was performed by simple incubation of an E. coli donor and a thermophile recipient without optimization of experimental conditions. Moreover, thermophile transformants were distinguished from abundant E. coli donor only by high temperature incubation. These observations suggest that conjugative plasmid transfer, particularly using E. coli BR408, is a facile and versatile approach for plasmid introduction into thermophilic Bacillus and Geobacillus spp., and potentially a variety of other thermophiles.  相似文献   

11.

Background

Starch is one of the most abundant organic polysaccharides available for the production of bio-ethanol as an alternative transport fuel. Cost-effective utilisation of starch requires consolidated bioprocessing (CBP) where a single microorganism can produce the enzymes required for hydrolysis of starch, and also convert the glucose monomers to ethanol.

Results

The Aspergillus tubingensis T8.4 α-amylase (amyA) and glucoamylase (glaA) genes were cloned and expressed in the laboratory strain Saccharomyces cerevisiae Y294 and the semi-industrial strain, S. cerevisiae Mnuα1. The recombinant AmyA and GlaA displayed protein sizes of 110–150 kDa and 90 kDa, respectively, suggesting significant glycosylation in S. cerevisiae. The Mnuα1[AmyA-GlaA] and Y294[AmyA-GlaA] strains were able to utilise 20 g l-1 raw corn starch as sole carbohydrate source, with ethanol titers of 9.03 and 6.67 g l-1 (0.038 and 0.028 g l-1 h-1), respectively, after 10 days. With a substrate load of 200 g l-1 raw corn starch, Mnuα1[AmyA-GlaA] yielded 70.07 g l-1 ethanol (0.58 g l-1 h-1) after 120 h of fermentation, whereas Y294[AmyA-GlaA] was less efficient at 43.33 g l-1 ethanol (0.36 g l-1 h-1).

Conclusions

In a semi-industrial amylolytic S. cerevisiae strain expressing the A. tubingensis α-amylase and glucoamylase genes, 200 g l-1 raw starch was completely hydrolysed (saccharified) in 120 hours with 74% converted to released sugars plus fermentation products and the remainder presumably to biomass. The single-step conversion of raw starch represents significant progress towards the realisation of CBP without the need for any heat pretreatment. Furthermore, the amylases were produced and secreted by the host strain, thus circumventing the need for exogenous amylases.
  相似文献   

12.
Twenty four rhizobial strains were isolated from root nodules of Melilotus, Medicago and Trigonella plants growing wild in soils throughout Egypt. The nearly complete 16S rRNA gene sequence from each strain showed that 12 strains (50 %) were closely related to the Ensifer meliloti LMG6133T type strain with identity values higher than 99.0 %, that 9 (37.5 %) strains were more than 99 % identical to the E. medicae WSM419T type strain, and that 3 (12.5 %) strains showed 100 % identity with the type strain of N. huautlense S02T. Accordingly, the diversity of rhizobial strains nodulating wild Melilotus, Medicago and Trigonella species in Egypt is marked by predominance of two genetic types, E. meliloti and E. medicae, although the frequency of isolation was slightly higher in E. meliloti. Sequencing of the symbiotic nodC gene from selected Medicago and Melilotus strains revealed that they were all similar to those of the E. meliloti LMG6133T and E. medicae WSM419T type strains, respectively. Similarly, nodC sequences of strains identified as members of the genus Neorhizobium were more than 99 % identical to that of N. galegae symbiovar officinalis HAMBI 114.  相似文献   

13.
Bacillus thuringiensis (Berliner) bears essential characteristics in the control of insect pests, such as its unique mode of action, which confers specificity and selectivity. This study assessed cry gene contents from Bt strains and their entomotoxicity against Diatraea saccharalis (F.) and Diatraea flavipennella (Box) (Lepidoptera: Crambidae). Bioassays with Bt strains were performed against neonates to evaluate their lethal and sublethal activities and were further analyzed by PCR, using primers to identify toxin genes. For D. saccharalis and D. flavipennella, 16 and 18 strains showed over 30% larval mortality in the 7th day, respectively. The LC50 values of strains for D. saccharalis varied from 0.08 × 105 (LIIT-0105) to 4104 × 105 (LIIT-2707) spores + crystals mL?1. For D. flavipennella, the LC50 values of strains varied from 0.40 × 105 (LIIT-2707) to 542 × 105 (LIIT-2109) spores + crystals mL?1. For the LIIT-0105 strain, which was the most toxic to D. saccharalis, the genes cry1Aa, cry1Ab, cry1Ac, cry1B, cry1C, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, cry8, and cry9C were detected, whereas for the strain LIIT-2707, which was the most toxic to D. flavipennella, detected genes were cry1Aa, cry1Ab, cry1Ac, cry1B, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, and cry9. The toxicity data and toxin gene content in these strains of Bt suggest a great variability of activity with potential to be used in the development of novel biopesticides or as source of resistance genes that can be expressed in plants to control pests.  相似文献   

14.
Maturation is one of the most important ontogenetic transitions in an individual’s life. However, the reproductive ecology of the tropical anguillid eel genus Anguilla at the onset of oceanic spawning migration is poorly understood. To understand the reproductive ecology, the fecundity of the tropical eels Anguilla bicolor bicolor, A. bengalensis bengalensis and A. marmorata was examined using advanced migrating silver eels (Stage IV and V). A close linear relationship was found between total length and fecundity in A. bengalensis bengalensis. The fecundities of A. bicolor bicolor (0.55 to 4.96 × 106), A. bengalensis bengalensis (0.33–1.72 × 106) and A. marmorata (0.99 × 106) were within the range of those observed in temperate eels.  相似文献   

15.
To identify potential linkages between specific bacterial populations and process performance in anaerobic digestion, the dynamics of bacterial community structure was monitored with high-throughput sequencing in triplicate anaerobic digesters treating animal waste. Firmicutes and Bacteroidetes were found as the two most abundant populations, however, with contrasting population dynamics in response to organic overloading. Firmicutes dominated the bacterial community during stable process performance at low organic loading rate, representing over 50 % of the bacterial abundance. In contrast, the onset of organic overloading raised the relative abundance of Bacteroidetes from 20 ± 2.6 to 44 ± 3.1 %. In addition to the significant negative correlation between the relative abundance of Firmicutes and Bacteroidetes, populations of Firmicutes and Bacteroidetes were found to be linked to process parameters including organic loading rate, volatile fatty acids concentration, and methane production. Therefore, the population abundance ratio of Firmicutes to Bacteroidetes (F/B ratio) was suggested as a potential indicator for process performance. The interactions between Firmicutes and Bacteroidetes populations could be exploited to develop strategies for the prevention of performance perturbation in anaerobic digestion processes.  相似文献   

16.
Approaches for in vitro regeneration and fabrication of synthetic seeds were formulated to support restoration in the wild and genetic manipulation of Ceropegia barnesii (categorized as endemic and endangered). MS medium augmented with 4 mg L?1 benzyl adenine was most advantageous for the production of multiple shoots from nodal explants. Fabrication of synthetic seeds was accomplished by sodium alginate encapsulation of nodes from microshoots. The most favorable medium combination for the induction of multiple shoots from synthetic seeds was MS medium complemented with 4 mg L?1 benzyl adenine and 1 mg L?1 gibberelic acid. Following root induction promoted by half strength MS basal medium augmented with indolebutyric acid, multiple shoots were subjected to hardening. Influence of vesicular-arbuscular mycorrhizal fungi on the hardening trials was investigated and it was observed that dual inoculation of Glomus aggregatum and G. intraradices enhanced the survival rate. The encapsulated nodes of C. barnesii were tested for their capability to endure different temperatures during storage and the optimal temperature for storage was found to be 4°C. A methodology for initiation of somatic embryogenesis from C. barnesii is also reported here, but embryos could not be induced to develop further. The micropropagated plants were reintroduced in to their natural habitat. This is the first report on micropropagation of C. barnesii.  相似文献   

17.
Hybridization between alien and native species is biologically very important and could lead to genetic erosion of native taxa. Solidago × niederederi was discovered over a century ago in Austria and described by Khek as a natural hybrid between the alien (nowadays regarded also as invasive) S. canadensis and native S. virgaurea. Although interspecific hybridization in the genus Solidago is considered to be relatively common, hybrid nature of S. × niederederi has not been independently proven using molecular tools, to date. Because proper identification of the parentage for the hybrid Solidago individuals solely based on morphological features can be misleading, in this paper we report an additive polymorphism pattern expressed in the ITS sequences obtained from individuals representing S. × niederederi, and confirm the previous hypothesis that the parental species of this hybrid are S. canadensis and S. virgaurea. Additionally, based on variability at the cpDNA rpl32-trnL locus, we showed that in natural populations hybridization occurs in both directions.  相似文献   

18.
In vitro culture and genetic transformation of black gram are difficult due to its recalcitrant nature. Establishment of gene transfer procedure is a prerequisite to develop transgenic plants of black gram in a shorter period. Therefore, genetic transformation was performed to optimize the factors influencing transformation efficiency through Agrobacterium tumefaciens-mediated in planta transformation using EHA 105 strain harbouring reporter gene, bar, and selectable marker, gfp-gus, in sprouted half-seed explants of black gram. Several parameters, such as co-cultivation, acetosyringone concentration, exposure time to sonication, and vacuum infiltration influencing in planta transformation, have been evaluated in this study. The half-seed explants when sonicated for 3 min and vacuum infiltered for 2 min at 100 mm of Hg in the presence of A. tumefaciens (pCAMBIA1304 bar) suspensions and incubated for 3 days co-cultivation in MS medium with 100 µM acetosyringone showed maximum transformation efficiency (46 %). The putative transformants were selected by inoculating co-cultivated seeds in BASTA® (4 mg l?1) containing MS medium followed by BASTA® foliar spray on 15-day-old black gram plants (35 mg l?1) in green house, and the transgene integration was confirmed by biochemical assay (GUS), Polymerase chain reaction, Dot-blot, and Southern hybridisation analyses.  相似文献   

19.
Sublethal concentrations of chemical insecticides may cause changes in some behavioral characteristics of natural enemies such as functional responses. The residual effect of three synthetic insecticides including deltamethrin, fenvalerate and azadirachtin were studied on functional response of Habrobracon hebetor Say to Ephestia kuehniella Zeller larvae. Seven host densities (2, 4, 8, 16, 32, 64 and 96) were used during a 24 h period. The resulting data were appropriately fit to Type II functional response models in all treatments: (1) control (0.0916 h?1; and T h  = 0.2011 h); (2) deltamethrin (a = 0.0839 h?1; and T h  = 0.3560 h); (3) fenvalerate (a = 0.0808 h?1 and T h  = 0.3623 h); and (4) azadirachtin (a = 0.0900 h?1 and T h  = 0.2042 h). Maximum theoretical parasitism rate (T/T h ) was 119.34 estimated for control wasps. There was no significant difference between the values of attack rates (a and a + D a ) in all treatments while the handling time was statistically affected in female wasps treated with fenvalerate. Our findings will be useful in safe application of these insecticides in pest management programmes.  相似文献   

20.
Antarctic benthos has been a main target in Antarctic research, but very few quantitative studies have been carried out in the littoral zone, which may be seasonally covered by macroalgae. In this work, we studied (1) cover and biomass of the macroalgae Iridaea cordata and Adenocystis utricularis, and (2) composition of macrobenthic assemblage associated with these macroalgal species at three locations at King George Island: Mareograph Beach (1 M), Tank’s Bay (2R) and Ardley Bay (3R). Iridaea cordata was collected by completely detaching the algae from the substrate, while A. utricularis was scraped. Adenocystis utricularis covered more than 80 % of the substrate at all locations, while coverage of Iridaea cordata was below 53 % or absent (3R). Fresh biomass of I. cordata was 0.8–61.4 g/individual and 4.7–93.0 g/100 cm2 for A. utricularis. The assemblage associated with both macroalgae differed significantly between sites. The studied fauna was composed mainly of amphipods, gastropods and bivalves. Species diversity was higher in the community associated with A. utricularis. A total of ~27 ind/g DW were found associated with I. cordata, while ~112 ind/g DW were found associated with A. utricularis. The most abundant groups associated with I. cordata were amphipods at 1 M (57 %) and gastropods at 2R (46 %). Both groups were responsible for the dissimilarity between localities (62.50 %). The most abundant groups associated with A. utricularis were the gastropods at all localities reaching up to 82 % at 1 M. This study provides a first baseline on the diversity and abundance of benthic assemblages associated with intertidal macroalgae in the southwest of King George Island.  相似文献   

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