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1.
Mucus is applied to substrates as snails move and when they rest. Beyond the use of mucus in movement and adhesion, the wide array of chemicals in mucus allows for supplemental use in communication. This communication is apparent in trail-following behavior. This study addresses the potential communication via mucus in selecting resting sites in a laboratory assay. In a series of six experiments, individuals of Cornu aspersum (which often rest on above-ground surfaces) were placed into lidded plastic containers with three or four sections swabbed with water (the control) or mucus, which included the test snail's own mucus, mucus from conspecifics from the same or a different container holding snails from the same lab colony, or from a different colony, and mucus from three additional snail species. The resting location was recorded on the following day. In two additional experiments, the facultative predator Rumina decollata was tested against conspecific and other snails' mucus. Individuals of C. aspersum preferentially rested in areas with the mucus of familiar conspecifics over mucus of unfamiliar conspecifics, a behavior that may contribute to homing and aggregation behaviors. There was evidence that juveniles may be less selective than adults. The mucus of only one of the three other species was avoided by individuals of C. aspersum. Unlike individuals of C. aspersum, individuals of the predator R. decollata avoided the mucus of conspecifics, which may be associated with less need for mate-finding in this self-fertilizing species. Individuals of R. decollata did not select among potential prey species.  相似文献   

2.
The antigenicities of external mucus from the sea anemones Stoichactis haddoni, Radianthus ritteri and Gyrostoma hertwigi and from the coral Trachyphyllia geoffroyi were compared. Marked differences were found between species but not within species. The differences suggested that mucus composition might be species specific, and hence that it might be one of the factors used by sea anemones and corals in the recognition of foreign anthozoan species.  相似文献   

3.
Background: Increased soil phosphorus (P) caused by agricultural intensification has been associated with decreased plant species richness (SR) in central Europe. How plant communities and soil P gradients are related in unimproved open habitats remains unclear.

Aims: The aim of this article was to characterise the relationship between soil chemical parameters and plant species composition and richness in unimproved open habitats.

Methods: The influence of soil chemical parameters (pH, P, K, Mg) on species composition was assessed, using data from 40 heathland and 54 grassland plots, by non-metric multidimensional scaling and permutational multivariate analysis of variance. The relationship between soil chemical parameters and SR was tested by linear mixed effects models.

Results: A direct relationship between heathland community composition and pH was observed, explaining 10% of variation in species composition, while P, Mg and pH together explained 17% of variation in grassland composition. In heathlands, SR increased with increasing pH, whereas in grasslands, SR decreased with increasing soil P.

Conclusions: Soil chemical parameters were substantially related to plant community composition and richness. In an area spared from a century of agricultural intensification, reduced pH appeared to constrain SR in heathlands, while even slight P increases (<10 mg kg?1) depressed plant SR in semi-natural grasslands.  相似文献   

4.
Fish mucus has previously been reported to change in appearance and composition among species and in response to changes in salinity and disease status. This study reports on the mucus viscosity and glycoprotein biochemistry of Atlantic salmon (Salmo salar L.), brown trout (Salmo trutta L.) and rainbow trout (Oncorhynchus mykiss Walbaum) in freshwater and seawater, both naïve to and affected by amoebic gill disease (AGD). Cutaneous mucus viscosity was measured over a range of shear rates (11.5, 23, 46 and 115 s–1), and non-Newtonian behaviour was demonstrated for all three species. Mucus viscosity was significantly greater in seawater than in freshwater for all species, and significantly lower in AGD-affected Atlantic salmon and brown trout. Mucus glucose, total protein and osmolality data indicated that differences in viscosity due to salinity were mostly attributed to changes in mucus hydration, while differences due to disease were mostly attributed to changes in mucus composition. Trends in gill mucus cell histochemistry included shifts in glycoproteins from neutral mucins in freshwater to acidic mucins in seawater, and shifts towards neutral mucins, with an increase in mucus cell numbers, in response to AGD. Results suggested that Atlantic salmon and brown trout are more similar to one another in their mucus profile than to rainbow trout. Atlantic salmon and brown trout both exhibited a whole-body mucus response to AGD, whereas rainbow trout exhibited only a local gill response. Findings hold implications for fish physiology and pathology, and indicate that future fish-disease management strategies should be species and condition specific.Communicated by I.D. HumeThe word mucus has been used in its noun form throughout the paper for clarity
An erratum to this article can be found at .  相似文献   

5.
Background: Trait-based assembly rules are a powerful tool in community ecology, used to explore the pattern and process of community structure (richness and composition).

Aims: A preliminary test for the utility of trait-based assembly rules in explaining cryptogamic epiphyte communities (lichens and bryophytes).

Methods: We sampled epiphytes from three different tree species (aspen, birch and pine), and from trees of contrasting age. The community composition of epiphyte species (taxon analysis) and functional groups (trait analysis) was summarised using multivariate ordination (nonmetric multidimensional scaling, NMDS).

Results: Ordination documented a widely observed pattern in which different tree species have taxonomically different epiphyte communities. However, NMDS sample scores were correlated to tree age in the trait-based analysis, but not in the taxon analysis.

Conclusions: Our results point to the existence of a common pattern in community traits during succession (on trees of different age) when measured for epiphyte communities with contrasting taxonomic composition. This pattern is evidenced by consistent trends in lichen growth form and reproductive strategy (sexual vs. asexual).  相似文献   

6.
【背景】温度在塑造大尺度的土壤微生物群落方面发挥了重要作用,但目前针对全球不同温度带大尺度土壤微生物多样性方面的研究十分缺乏。【目的】明确不同温度带大尺度土壤微生物组成和功能的差异变化。【方法】从宏观的角度运用宏基因组技术对不同温度带土壤微生物群落的组成和功能进行分析。【结果】细菌的物种多样性随着温度带纬度的升高而增多,真菌的物种多样性在温带最多,在寒带最小且假丝酵母属(Candida)占绝对优势。3个温度带间除物种多样性存在差异外,微生物群落中物种丰度差异也较大,优势属和特殊属各有不同。其中值得注意的是,假单胞菌属(Pseudomonas)和芽孢杆菌属(Bacillus)的丰度在不同温度带间存在显著差异,且随着温度带纬度的升高而增多,而链霉菌属(Streptomyces)、地嗜皮菌属(Geodermatophilus)、红色杆菌属(Rubrobacter)和小单孢菌属(Micromonospora)的丰度随温度带纬度的升高而降低。在功能方面,发现与翻译后修饰、蛋白质周转、伴侣(posttranslational modification, protein turnover, chap...  相似文献   

7.
Abstract

Karyological and chemical variations in Allium sativum L. — Results about a research on the karyotypes of three Italian strains of Allium sativum are reported. The lack of sexual reproduction in Allium sativum favours the formation of strains regarded as clones; each of them represents an isolated genetic system. The anatomy and the chemical composition of the essence was studied to improve the understanding of the variations in the different strains comprised in this species. Two of the clones examined (Tuscan and Sicilian) belong to U type and one (Piedmontese) to the H type, according to Hrubý and Konvi?ka's classification based on the morpho-physiological characters. In this study evidence shows that: a) The three clones do not present anatomical differences. b) The morpho-physiological characters are strictly correlated with the chemical composition of the essence; in fact the gas-chromatographic study of the two U type clone essences shows the same qualitative composition, each chemical component being present more or less in the same percentage. The essence of Piedmontese clone, is qualitatively and quantitatively different from the others. c) The number and the general morphology of the chromosomes of the three root tip karyotypes agree with the literature, nevertheless the karyotypes sometimes show differences in the two satellited pairs of chromosomes. The Tuscan karyotype (U type) is comparable with the OU type of Konvi?ka and Levan. The Piedmontese karyotype (H type) is comparable with the OH karyotype of the same authors; instead the Sicilian karyotype is very different from all karyotypes in literature and from the Tuscan karyotype belonging to the same U type because of the lack of the pseudosatellite in a partner of pair no. 6. Research evidences that, for the time being, it is impossible to use only chromosome morphology to establish the clone types: nevertheless their chemical characteristics seem to correspond to their morpho-physiological features.  相似文献   

8.
【背景】垫状点地梅作为青藏高原最具代表性的垫状植物,其叶际和内生微生物对适应极端环境有重要意义,同时也是一种独特的资源。【目的】探究垫状点地梅叶际和叶内可培养微生物多样性,以及不同生存状态个体之间的微生物差异。【方法】采用纯培养方法分离和纯化3个不同地区垫状点地梅叶际和叶内的细菌、酵母菌和丝状真菌,并用16S rRNA基因和ITS区域序列进行分析鉴定。【结果】最终得到叶际微生物350株,鉴定为22属49种,优势种为Penicillium sajarovii;内生微生物274株,鉴定为19属45种,优势种为Bacillusmycoides;两者的优势属均为Penicillium。垫状点地梅叶际和叶内之间及不同生存状态个体之间微生物的α多样性大多无显著差异,各群落间的成员也有重叠,但物种组成存在显著的空间异质性。【结论】垫状点地梅叶际和叶内有着丰富的可培养微生物资源,来源于不同生存状态的个体或不同部位的微生物物种组成差别较大,微生物对不同环境的选择偏好形成了不同的群落模式。但这些不同来源的微生物群落之间同样存在高比例的共有菌株,这些共有菌株的异养方式和生态位并不固定,可兼共生和腐生生存,生...  相似文献   

9.

Physalia physalis, the Portuguese man of war, consumes mostly fish and fish larvae. Intracellular recordings from nematocyst‐containing cells (cnidocytes) in small pieces of Physalia tentacle were used to quantify the electrical responses to diluted and filtered fish skin mucus, 1–100 x 10‐6 M amino acids, monosaccharides, and nucleosides, and seawater, which were delivered upstream of the tissue. Seawater caused responses (one pulse only) in about 10% of the applications. Fish mucus extract elicited responses in all applications, producing 1–18 depolarizing pulses (20 mV maximum amplitude). The pulses were characteristic of post‐synaptic potentials (EPSPs). Lucifer yellow and biocytin dye injections showed that the cnidocytes were not electrically coupled. Simultaneous records from two cnidocytes following mucus applications were identical.We propose, therefore, that the chemoreceptors are not on the cnidocytes, but are probably on sensory neurons that innervate clusters of cnidocytes. A < 3,000 MW fraction of mucus elicited responses indistinguishable from whole mucus extract. Higher molecular weight fractions caused no response. The various test solutions had lower percentages of response (47–92%) and produced significantly fewer pulses than the mucus extract. We conclude that prey capture in Physalia is facilitated by chemicals present in the mucus covering their fish prey. The chemical stimuli probably sensitize the nematocysts to discharge upon mechanical stimulation.  相似文献   

10.
 Plants produce volatile compounds known to influence insect preferences for oviposition and feeding. To examine whether volatile leaf compounds are correlated with the herbivorous insect community, we analyzed volatile compounds in leaves from three co-occurring willow species, Salix serissaefolia, S. eriocarpa, and S. integra, and investigated their associated insect communities in 3 months across different years. The gas chromatographic profiles of volatile compounds were highly specific to each willow species and remained constant in the study months. In a comparison between the chemical composition of the volatile compounds and the taxon composition of the insect communities, dissimilarity patterns in chemical composition among the three willow species were very close to those in herbivorous insect communities. These findings indicate that willow leaves produce specific volatiles that are highly correlated with the community structure of herbivorous insects associated with them. Received: October 10, 2002 / Accepted: March 17, 2003  相似文献   

11.
Background: Boreal forest understory plant communities are known to be resilient to fire – the species composition of stands after a fire is quite similar to the pre-fire composition. However, we know little about recovery of individual plants within particular locations in forest stands (i.e. plot-level changes) since we usually do not have pre-fire data for plots.

Aims: We wanted to determine whether species recruited into the same or different locations in a Pinus banksiana stand that experienced a severe wildfire.

Methods: We used pre-existing permanent plots to evaluate the cover of understory after an unplanned wildfire.

Results: Across the entire stand nine of 47 species showed a significant change in cover. The largest change in a plant functional group was in the mosses, with all species present before fire being eliminated. There was no change in species diversity or total cover. At the plot level, species composition showed a much greater change. An average of 47% of the species present in a plot before the fire were absent in the same plot after the fire, and the total species turnover in plots was 88% of the species present before the fire. The plots showed a similar shift in species composition.

Conclusions: These results confirm that boreal forest communities show a high degree of resilience to fire, but within a forest stand species will be found in different locations following fire, potentially exposing them to a different set of biotic and abiotic conditions in these new locations.  相似文献   

12.
Indirect immunofluorescence assays were conducted on cryotome sections of four terrestrial slug species from three distinct phylogenetic groups, Arion ater (L.), Arion hortensis (Férussac), Tandonia (Milax) budapestensis (Hazay), and Deroceras reticulatum (Müller) using monoclonal antibodies for two glycosaminoglycans (GAGs), heparan sulphate, and chondroitin sulphate. Specific staining for a heparan sulphate-like component was demonstrated in the foot and tail regions of each species and was particularly intense in A. ater and A. hortensis, notably in the epidermis and associated mucus-like material, and in mucus-like material from the pedal gland region of the latter species. Subsequent studies with A. ater confirmed the presence of heparan-sulphate–like activity in the caudal gland duct region. No evidence of specific staining for chondroitin sulphate-like activity was found in any of the slug species. This work suggests that a specific GAG, or a group of closely related GAGs, is a common component of mucus in a range of slug species and of different types of mucus, including trail (pedal) mucus and the more viscous mucus produced by the caudal gland.  相似文献   

13.
The purpose of this study was to assess degradation and utilization of the mucus produced by 3 coral reef Anthozoa (Sarcophyton, Fungia and Acropora) by microorganisms. This was achieved by carrying out long term in situ incubations at Nouméa lagoon (New Caledonia).The microbial population including bacterial and eukaryotic cells was monitored by cell counts, cultures of mucus degraders, and by estimation of microbial activity from the pool of adenylates and enzymatic activity. In addition the chemical composition (C and N) of the mucus was monitored and its morphological features were observed by scanning electron microscope (SEM).Only slight differences were found between the 3 types of mucus studied. On the whole, they follow the same pattern of change. After a short bacterial growth phase (4 days), a bloom of eukaryotes (Flagellates, Ciliates and Diatoms) was observed. This eukaryote population remained constant for at least 10 days. A similar pattern has been described in the breakdown of detritus of plant origin.Several observations suggest that bacteria utilize only certain components of mucus, the most widely used being proteins, triglycerides and wax esters; these latter two compounds are known to be the dissolved photosynthetic products released by zooxanthellae during mucus secretion. Neither bacteria nor eukaryotes completely degrade the mucus web even after 21 days of incubation. The likelihood that mucus excretion is a defensive reaction against physical and chemical stresses might explain why mucus is a poor, or even inhibiting medium for the bacterial degraders isolated from the mucus itself.  相似文献   

14.
《Plant Ecology & Diversity》2013,6(5-6):509-520
Background: Burial mounds (kurgans) of Eurasian steppes are man-made habitat islands that have the potential to harbour rich plant diversity due to micro-habitats associated with their topography.

Aims: We assessed whether kurgan micro-habitats harboured different species pools and functional groups from those found on the surrounding steppes. In addition, we asked if these mounds were affected by different grazing intensities from those on the surrounding vegetation.

Methods: We surveyed kurgan micro-habitats (northern and southern slopes, surrounding ditch) and adjacent steppe plains in non-grazed, moderately grazed and heavily grazed sites in northern Kazakhstan. We analysed differences in species composition of four habitats under three grazing regimes using Generalised Linear Mixed Models, PCA ordination and indicator species analysis.

Results: Kurgan micro-habitats had diverse vegetation and supported the co-existence of plant species with different environmental needs. We identified 16 steppe specialists confined to kurgan micro-habitats. Steppe vegetation was well-adapted to extensive grazing, although heavy grazing supported ruderals and a decline in steppe specialists. There was a significant interaction between grazing intensity and habitat type: heavy grazing supported ruderals and suppressed steppe specialists especially on the slopes.

Conclusions: We highlighted that kurgans play an important role as maintaining high plant diversity locally in extensive steppe plains in Central-Asia by increasing environmental heterogeneity and supporting specialist species confined to these micro-habitats.  相似文献   

15.
The most common European gastropod species, Arion vulgaris, is one of the most troublesome pests for private garden owners and commercial agriculturists. The sticky and hard to remove secretion produced by these animals allows them to overcome most artificial and natural barriers. However, this highly adherent biopolymer has recently shown great potential for novel wound-healing applications in medicine. Nevertheless, our knowledge of the underlying gland system is still limited and few studies on the ventral gland system are available. We studied the lateral and ventral pedal glands in Arion vulgaris to determine their secretory content histochemically and through lectin assays. Using these histological and histochemical methods we differentiate five gland types with different mucus composition in the lateral pedal region of the foot of Arion vulgaris. These contain sulphated and carboxylated mucosubstances (positive Alcian blue staining) but lack hexose-containing mucosubstances (negative PAS staining). In the ventral pedal region, four gland types can be differentiated producing sulphated and carboxylated mucosubstances. Within the ventral mucus, a high affinity for the lectins PNA and WGA is observed. While the lateral glands are histochemically negative for PAS, a positive staining with the lectin JAC is observed. Arion vulgaris shows clear morphological differences from other arionid species. This raises the question whether the variation in the chemistry of the secretory material and mucus composition is the result of different functions and/or is related to the animals' different environmental conditions. A comparison of some glands of Arion vulgaris with those of the helicid species Helix pomatia and Cepaea hortensis indicates morphological similarities.  相似文献   

16.
Comparative studies on the distribution of archaeal versus bacterial communities associated with the surface mucus layer of corals have rarely taken place. It has therefore remained enigmatic whether mucus-associated archaeal and bacterial communities exhibit a similar specificity towards coral hosts and whether they vary in the same fashion over spatial gradients and between reef locations. We used microbial community profiling (terminal-restriction fragment length polymorphism, T-RFLP) and clone library sequencing of the 16S rRNA gene to compare the diversity and community structure of dominant archaeal and bacterial communities associating with the mucus of three common reef-building coral species (Porites astreoides, Siderastrea siderea and Orbicella annularis) over different spatial scales on a Caribbean fringing reef. Sampling locations included three reef sites, three reef patches within each site and two depths. Reference sediment samples and ambient water were also taken for each of the 18 sampling locations resulting in a total of 239 samples. While only 41% of the bacterial operational taxonomic units (OTUs) characterized by T-RFLP were shared between mucus and the ambient water or sediment, for archaeal OTUs this percentage was 2-fold higher (78%). About half of the mucus-associated OTUs (44% and 58% of bacterial and archaeal OTUs, respectively) were shared between the three coral species. Our multivariate statistical analysis (ANOSIM, PERMANOVA and CCA) showed that while the bacterial community composition was determined by habitat (mucus, sediment or seawater), host coral species, location and spatial distance, the archaeal community composition was solely determined by the habitat. This study highlights that mucus-associated archaeal and bacterial communities differ in their degree of community turnover over reefs and in their host-specificity.  相似文献   

17.
《Plant Ecology & Diversity》2013,6(2-3):251-264
Background: Rock outcrops have been shown to provide specific conditions for bryophyte communities, but no studies have focused on the importance of microhabitats on such communities.

Aim: To analyse the distribution pattern of bryophyte species from granite and schist outcrops in three microhabitats (rock surfaces, fissures and cavities) in Portugal.

Methods: Sample plots were established in fissures, cavities and on rock surfaces of rock outcrops in north and central Portugal. Micro-scale variables, such as exposure and slope were assessed for each microhabitat.

Results: The microhabitats most different in species composition were surfaces versus cavities and surfaces versus fissures, both on granite and schist. Short-lived shuttle species tended to be associated with surfaces, and perennial species were more frequent in cavities and fissures. Both on granite and schist, the number of species found in each microhabitat was highest in cavities, followed by fissures and rock surfaces. The most relevant predictors of bryophyte richness were microhabitat type, exposure and rock type.

Conclusions: This investigation confirmed that rock microhabitats play an important role in bryophyte diversity by promoting habitat heterogeneity. In addition, our results clearly suggest local explanations for variation in bryophyte species richness and communities.  相似文献   

18.
Background: Most studies on tropical bryophytes deal with epiphytic species. This is the first ecological study of tropical forests that focuses specifically on terrestrial bryophytes.

Aim: To investigate the differences between slope and ridge environments in upper montane forests of southern Ecuador in terms of species diversity (richness, abundance), species composition and life forms of terrestrial bryophytes.

Methods: We used Non-metric Multidimensional Scaling (NMDS) to group bryophyte relevés by study location, habitat type and exposure class. Species indicator values were calculated and compared for different habitats.

Results: In total, 140 species were recorded, the majority being liverworts. NMDS analyses and Mantel correlations clearly separated between slope and ridge relevés, and between sunny and shaded microhabitats on ridges. Bryophyte life forms also showed different distribution patterns in slope and in ridge habitats. Mosses were more prominent in sunny than in shaded microhabitats.

Conclusions: Environmental differentiation between ridges and slopes, and small-scale variation in microclimatic conditions caused by differences in exposure, were stronger predictors of species richness and composition than geographical distance between study sites.  相似文献   

19.
In this study, the traditional culture-based technique and the 16S rDNA sequencing method were used to investigate the characterization of bacterial community in the stomach contents and mucus of yellow catfish (Pelteobagrus fulvidraco). The culture-based technique disclosed that the average bacterial numbers in the gastric contents and mucus were 5.79 × 107 cfu/g (cfu: colony forming unit) and 1.89 × 105 cfu/g, respectively. Several different bacteria were obtained from gastric contents, including species from genera Bradyrhizobium, Phyllobacterium, Plesiomonas, Hafnia, Edwardsiella, Pseudomonas, and Bacillus. However, only two species were isolated from the gastric mucus, including species from genera Plesiomonas and Aeromonas. Forty-five phylotypes were observed from the 65 positive clones from the stomach contents (library SC); nineteen phylotypes were detected from the 45 clones from the stomach mucus (library SM). Further analyses revealed that the fish stomach harbored characteristic microbiota, where Firmicutes was dominant, followed by Proteobacteria and Bacteroidetes and Fusobacteria. This characterization of bacterial community is markedly different from that of the fish intestine, where Proteobacteria is predominant, followed by Fusobacteria and Firmicutes. Chloroflexi (1.5%) was only found in the library SC, while Actinobacteria (4.4%) was only found in the library SM, suggesting that microbiota of GI contents was quite different from that of GI mucus. In addition, several species of bacteria found in the stomach may be potentially opportunistic pathogens, indicating that fish digestive tract is a reservoir for many nosocomial pathogens.  相似文献   

20.
《Plant Ecology & Diversity》2013,6(2-3):217-229
Background: Urbanisation filters species in communities depending on their adaptability to conditions in built-up areas, especially in semi-natural habitats. Roadside vegetation is widespread along urban-rural gradients and is therefore a good place to study landscape-scale factors influencing plant community composition.

Aim: Our study aimed to assess how plant species distributions vary between urban and rural landscape contexts and to identify biological traits favoured in urban areas.

Methods: Presence/absence data for 63 indigenous common species were collected in 296 road verge patches distributed along the urban–rural gradient in three French cities. We investigated the effects of landscape composition on species assemblages and related individual species responses to urbanisation to functional traits associated with dispersal and persistence capacity.

Results: Many grassland species were negatively affected by increasing proportion of built-up areas in the landscape. Insect-pollination and high seed production appeared to be key traits favoured in grassland communities in urban areas, whereas dispersal modes were less related to plant distribution.

Conclusions: This study has demonstrated that urban filters affect common species of widespread, managed road verges. Better knowledge of the flora of these herbaceous roadsides may contribute to the conservation of common biodiversity within other grassland habitats found in urban areas.  相似文献   

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