A combined transmission electron microscopy (TEM) and Fourier transform analysis has been performed on the secretory granules storing active peptides/proteins in serous cutaneous glands of n?=?12 anuran species. Previous TEM investigation showed that the granules are provided with remarkable repeating substructures based on discrete subunits, arranged into a consistent framework. Furthermore, TEM findings revealed that this recurrent arrangement is acquired during a prolonged post-Golgian (or maturational) processing that affects the secretory product. Maturation leads to a variety of patterns depending on the degree of subunit clustering. This variety of recurrent patterns has been plotted into a range of frequency spectra. Through this quantitative approach, we found that the varying granule substructure can be reduced to a single mechanism of peptide/protein aggregation. 相似文献
Sociality in mole rats has been suggested to have evolved as a response to the widely dispersed food resources and the limited burrowing opportunities that result from sporadic rainfall events. In the most arid regions, individual foraging efficiency is reduced, and energetic constraints increase. In this study, we investigate seasonal differences in burrow architecture of the social Cryptomys hottentotus hottentotus in a mesic region. We describe burrow geometry in response to seasonal weather conditions for two seasons (wet and dry). Interactions occurred between seasons and colony size for the size of the burrow systems, but not the shape of the burrow systems. The fractal dimension values of the burrow systems did not differ between seasons. Thus, the burrow complexity was dependent upon the number of mole rats present in the social group. 相似文献
Pathogens exert a strong selection pressure on organisms to evolve effective immune defences. In addition to individual immunity, social organisms can act cooperatively to produce collective defences. In many ant species, queens have the option to found a colony alone or in groups with other, often unrelated, conspecifics. These associations are transient, usually lasting only as long as each queen benefits from the presence of others. In fact, once the first workers emerge, queens fight to the death for dominance. One potential advantage of co-founding may be that queens benefit from collective disease defences, such as mutual grooming, that act against common soil pathogens. We test this hypothesis by exposing single and co-founding queens to a fungal parasite, in order to assess whether queens in co-founding associations have improved survival. Surprisingly, co-foundresses exposed to the entomopathogenic fungus Metarhizium did not engage in cooperative disease defences, and consequently, we find no direct benefit of multiple queens on survival. However, an indirect benefit was observed, with parasite-exposed queens producing more brood when they co-founded, than when they were alone. We suggest this is due to a trade-off between reproduction and immunity. Additionally, we report an extraordinary ability of the queens to tolerate an infection for long periods after parasite exposure. Our study suggests that there are no social immunity benefits for co-founding ant queens, but that in parasite-rich environments, the presence of additional queens may nevertheless improve the chances of colony founding success. 相似文献
Several social mammals, including elephants and some primates, whales and bats, live in multilevel societies that form temporary subgroups. Despite these fission–fusion dynamics, group members often maintain long-term bonds. However, it is unclear whether such individual links and the resulting stable social subunits continue to exist after a complete reorganisation of a society, e.g. following a population crash. Here, we employed a weighted network analysis on 7,109 individual roosting records collected over 4 years in a wild Bechstein’s bat colony. We show that, in response to a strong population decline, the colony’s two stable social subunits fused into a non-modular social network. Nevertheless, in the first year after the crash, long-term bonds were still detectable, suggesting that the bats remembered previous individual relationships. Our findings are important for understanding the flexibility of animal societies in the face of dramatic changes and for the conservation of social mammals with declining populations.
Algae biomass is an attractive biofuel feedstock when grown with high productivity on marginal land. Hydrothermal liquefaction (HTL) produces more oil from algae than lipid extraction (LE) does because protein and carbohydrates are converted, in part, to oil. Since nitrogen in the algae biomass is incorporated into the HTL oil, and since lipid extracted algae for generating heat and electricity are not co-produced by HTL, there are questions regarding implications for emissions and energy use. We studied the HTL and LE pathways for renewable diesel (RD) production by modeling all essential operations from nutrient manufacturing through fuel use. Our objective was to identify the key relationships affecting HTL energy consumption and emissions. LE, with identical upstream growth model and consistent hydroprocessing model, served as reference. HTL used 1.8 fold less algae than did LE but required 5.2 times more ammonia when nitrogen incorporated in the HTL oil was treated as lost. HTL RD had life cycle emissions of 31,000 gCO2 equivalent (gCO2e) compared to 21,500 gCO2e for LE based RD per million BTU of RD produced. Greenhouse gas (GHG) emissions increased when yields exceeded 0.4 g HTL oil/g algae because insufficient carbon was left for biogas generation. Key variables in the analysis were the HTL oil yield, the hydrogen demand during upgrading, and the nitrogen content of the HTL oil. Future work requires better data for upgrading renewable oils to RD and requires consideration of nitrogen recycling during upgrading. 相似文献
Torque teno virus (TTV) was surveyed in tap water collected in schools from three municipalities located in the south of Brazil. TTV genomes were found in 11.7 % (4/34) of the samples. TTV DNA was detected in 10.5 % (2/19) of the samples collected at the city of Caxias do Sul and in 25 % (2/8) of the samples from Pelotas. Those cities have a low rate of sewage treatment. All samples from Santa Cruz do Sul, which has nearly 92 % of its sewage treated, were negative. These results suggest that the amount of sewage treated may have an effect on the detection rates of TTV DNA in drinking water in a given urban area, showing a mild negative correlation (r = ?0.76), when comparing the percentage of sewage treatment to the detection of TTV genomes. The detection rate of TTV was also compared with Escherichia coli, showing a strong correlation (r = 0.97), indicating that TTV may be a suitable marker of fecal contamination. 相似文献
We explored the possible future impacts of increased coastal flooding due to sea level rise and the potential adaptation responses
of two urban, environmental justice communities in the metropolitan Boston area of Massachusetts. East Boston is predominantly
a residential area with some industrial and commercial activities, particularly along the coastal fringe. Everett, a city
to the north of Boston, has a diversified industrial and commercial base. While these two communities have similar socioeconomic
characteristics, they differ substantially in the extent to which residents would be impacted by increased coastal flooding.
In East Boston, a large portion of residents would be flooded, while in Everett, it is the commercial/industrial districts
that are primarily vulnerable. Through a series of workshops with residents in each community, we found that the target populations
do not have an adaptation perspective or knowledge of any resources that could assist them in this challenge. Furthermore,
they do not feel included in the planning processes within their communities. However, a common incentive for both communities
was an intense commitment to their communities and an eagerness to learn more and become actively engaged in decisions regarding
climate change adaptation. The lessons that can be applied to other studies include 1) images are powerful tools in communicating
concepts, 2) understanding existing cultural knowledge and values in adaptation planning is essential to the planning process
and 3) engaging local residents at the beginning of the process can create important educational opportunities and develop
trust and consensus that is necessary for moving from concept to implementation. 相似文献
Indentifying common priorities in shared natural resource systems constitutes an important platform for implementing adaptation
and a major step in sharing a common responsibility in addressing climate change. Predominated by discourses on REDD + (Reduced
Emissions from Deforestation and Forest Degradation and conservation, sustainable management of forests and enhancement of
forest carbon stocks in developing countries) with little emphasis on adaptation there is a risk of lack of policy measures
in addressing climate change in the Congo Basin. Forest products and ecosystem services provide security portfolios for the
predominantly rural communities, and play major roles in national development programmes in both revenue and employment opportunities.
Thus, raising the profile of forests in the policy arena especially in the twin roles of addressing climate change in mitigation
and adaptation and achieving resilient development is crucial. Within the framework of the Congo Basin Forests and Climate
Change Adaptation project (COFCCA) project, science policy dialogue was conducted to identify and prioritize forest based
sectors vulnerable to climate change but important to household livelihoods and national development. The goal of the prioritization
process was for the development of intervention in forest as measures for climate change adaptation in Central Africa. Participants
constituted a wide range of stakeholders (government, Non Governmental Organizations, research institutions, universities,
community leaders, private sectors etc.) as representatives from three countries directly involved in the project: Cameroon,
Central African Republic and Democratic Republic of Congo. Building on national priorities, four forest related sectors were
identified as common priorities at the regional level for focus on climate change adaptation. These sectors included: (1)
energy with emphasis on fuel wood and Charcoal; (2) Water principally quality, quantity, accessibility, etc.; (3) Food with emphasis on Non Timber Forest Products, and (4) Health linked to healthcare products (medicinal plants). Using these prioritized sectors, the project focused on addressing the impacts of climate change on local communities and the development of adaptation strategies in the three pilot countries
of the Congo Basin region. The four sectors constitute the key for development in the region and equally considered as priority sectors in the poverty
reduction papers. Focused research on these sectors can help to inject the role of forests in national and local development
and their potentials contributions to climate change adaptation in national and public discourses. Mainstreaming forest for
climate change adaptation into national development planning is the key to improve policy coherence and effectiveness in forest
management in the region. 相似文献
Myrmecophily provides various examples of how social structures can be overcome to exploit vast and well-protected resources.
Ant nest beetles (Paussinae) are particularly well suited for ecological and evolutionary considerations in the context of
association with ants because life habits within the subfamily range from free-living and predatory in basal taxa to obligatory
myrmecophily in derived Paussini. Adult Paussini are accepted in the ant society, although parasitising the colony by preying
on ant brood. Host species mainly belong to the ant families Myrmicinae and Formicinae, but at least several paussine genera
are not host-specific. Morphological adaptations, such as special glands and associated tufts of hair (trichomes), characterise
Paussini as typical myrmecophiles and lead to two different strategical types of body shape: while certain Paussini rely on
the protective type with less exposed extremities, other genera access ant colonies using glandular secretions and trichomes
(symphile type). We compare these adaptations with other taxonomic groups of insects by joining contemporary research and
early sources and discuss the possibility of an attracting or appeasing effect of the secretion. Species that are ignored
by their host ants might use chemical mimicry instead. Furthermore, vibrational signals may contribute to ant–beetle communication,
and chemical signals have proven to play a role in host finding. The powerful defense chemistry of paussines as “bombardier
beetles” is not used in contact with host ants. We attempt to trace the evolution of myrmecophily in paussines by reviewing
important aspects of the association between paussine beetles and ants, i.e. morphological and potential chemical adaptations,
life cycle, host specificity, alimentation, parasitism and sound production.
(E)-6,10-dimethyl-5,9-undecadien-2-ol (geranyl acetol), termed here fuscol, was identified as a male-produced pheromone emitted
by Tetropium fuscum (F.) and Tetropium cinnamopterum Kirby. In field experiments, traps baited with synthetic fuscol alone were not significantly attractive, but the combination
of fuscol plus host volatiles (a synthetic blend of monoterpenes plus ethanol) attracted significantly more male and female
T. fuscum and female T. cinnamopterum than did host volatiles alone. This is the first homoterpenoid alcohol to be described in the Cerambycidae, and the first
pheromone reported from the sub-family Spondylidinae. 相似文献