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1.
Understanding wildlife movements and habitat selection are critical to drafting conservation and management plans. We studied a population of eastern Hermann’s tortoise (Testudo hermanni boettgeri) in a traditionally managed rural landscape in Romania, near the northern edge of the species geographic distribution. We used telemetry to radio-track 24 individuals between 2005 and 2008 and performed a Euclidian distance-based habitat selection analysis to investigate habitats preferred by tortoises at both landscapes (second-order order selection) and individual (third-order selection) home range scales. The home range size for tortoises in our study area was 3.79?±?0.62 ha and did not differ by gender or season (pre- and post-nesting seasons). Their movement ecology was characterized by short-distance movements (daily mean?=?31.18?±?1.59 m), apparently unaffected by habitat type. In contrast to other studies, movements of males and females were of similar magnitude. At the landscape (population home range) scale, grasslands and shrubs were preferred, but tortoises also showed affinity to forest edges. At the individual home range scale, tortoises selected grassland and shrub habitats, avoided forests, and used forest edges randomly. Creeks were avoided at both spatial scales. Our results suggest that tortoise home ranges contain well-defined associations of habitats despite a higher selection for grasslands. As such, avoiding land conversion to other uses and maintaining habitat heterogeneity through traditional practices (e.g., manual mowing of grasslands, livestock grazing) are critical for the persistence of tortoise populations.  相似文献   

2.
In mammalian oocytes, fertilization-associated calcium [Ca2+]i oscillations are responsible for the activation of development. The mechanism(s) by which the sperm triggers the initial [Ca2+]i rise and supports long-lasting oscillations is not resolved. It has been proposed that the sperm may interact with receptors in the oocyte's plasma membrane and engage intracellular signaling pathways that result in Ca2+ release. A different line of investigation suggests that upon sperm-oocyte fusion, a sperm cytosolic factor is released into the oocyte which interacts with unknown cytosolic targets, and generates [Ca2+]i oscillations. We will discuss the most recent evidence for both lines of thought and demonstrate that injections of sperm crude extracts (SF) into mammalian oocytes trigger [Ca2+]i oscillations that support in vitro parthenogenetic development to the blastocyst stage.  相似文献   

3.

Purpose

To promote eco-efficient sugarcane products, there is a need for life cycle assessment (LCA) methods that enable rapid assessment of the environmental implications of alternative agricultural practices. In response, a customised LCA method for sugarcane growing was developed and operationalized in the CaneLCA tool. The aim of the paper was to describe the CaneLCA method in detail and to test the effectiveness of the tool’s parameterisation for evaluating the environmental implications of cane growing practice alternatives.

Methods

CaneLCA (Version 1.03) was developed over 6 years (2011–2017) in conjunction with the Australian sugarcane sector. The LCA process was customised for sugarcane growing by focusing on ‘cradle to farm gate’ operations and relevant impact categories, and by parameterising practice variables. To evaluate the effectiveness of the tool, we used it to assess a case study of actual practice changes in the Wet Tropics region of Australia, in terms of the scope of practice variables and environmental implications that can be accounted for.

Results and discussion

The case study results generated by CaneLCA were consistent with those generated by past studies using LCA software. The parameterisation of practice variables allowed for all the practice changes represented in the case study to be assessed. It is suitable for evaluating such known practice alternatives, but less suited to evaluating very innovative practice alternatives, as it is constrained by the underlying algorithms and factors. Most of the environmental implications could be considered, except for effects on soil quality. This will be an area for future tool development to understand the full implications of agricultural practice change, along with the introduction of dynamic models to better estimate emissions.

Conclusions

CaneLCA makes the LCA process more rapid for evaluating alternative sugarcane growing practices, thereby speeding up progress towards devising more eco-efficient sugarcane products. It provides a model that could be adapted for other sugarcane growing regions, and for other perennial cropping systems. The novelty of the method is the detailed parameterisation of practice variables so that a wide range of alternative practices can be evaluated.
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4.
 We report the cloning and characterization of the gene ABNORMAL FLORAL ORGANS (AFO), which is required for normal flower development in Arabidopsis. afo mutant flowers show defects in all four floral whorls. The number of organs in each whorl varies. Most flowers consist of reduced numbers of petals and stamens, even though supernumerary sepals and carpels may be observed. Abnormal organ structure is evident from an early stage. Mosaic first whorl organs are common, with some sepals taking on petaloid or staminoid characteristics. Stamens are often deformed, having thin filaments and reduced anthers, yet occasionally producing viable pollen. Partial fertility is indicated by some seed setting. The afo-1 mutation is caused by insertion of a gene trap Ds transposable element. The AFO gene was cloned and is predicted to encode a novel protein of 229 amino acids. The expression of AFO mRNA by northern blot analysis in combination with mutant phenotype suggests that the AFO gene product plays an important role in Arabidopsis flower development. We also report that antherless, a previously described male-sterile mutation, is allelic to afo-1. Received: 3 September 1998 / Revision accepted: 15 December 1998  相似文献   

5.
The Tamm–Horsfall glycoprotein prepared by salt precipitation from urine was found to comprise a heterogeneous collection of aggregates. These could be disaggregated with 8m-urea, following which chromatography on a column of Bio-Gel A.15m yielded a homogeneous glycoprotein of mol.wt. 73000 together with several unidentified impurities. Gel filtration of normal plasma showed the glycoprotein to exist predominantly in a form that is eluted identically with the purified preparation. In one case, material of higher molecular weight was also detected. The purified glycoprotein was used to develop a rapid specific radioimmunoassay for its measurement in human serum or plasma by the use of the Tamm–Horsfall glycoprotein, labelled with 125I by the chloramine-t method as the tracer, an antiserum raised in rabbits, and separation of the bound and free fractions by a second antibody covalently linked to magnetizable particles. Parallelism was demonstrated between the standard preparation and samples. Recovery of added standard to serum varied between 99 and 109%. Total assay time was less than 4h with an intra-assay and inter-assay coefficient of variation of less than 10%. There were no significant differences in the ranges covered with regard to either age or sex, and no circadian rhythm was observed in normal subjects. A physiological range of 70–540ng/ml was established based on serum samples from 95 subjects with normal renal function, as defined by their serum creatinine and urea concentrations. No Tamm–Horsfall glycoprotein was detected in the serum of six anephric patients.  相似文献   

6.
Folates have a key role in metabolism, and the folate-dependent generation of DNA precursors in the form of deoxythymidine 5'-phosphate is particularly important for the replication of malaria parasites. Although Plasmodium falciparum can synthesize folate derivatives de novo, a long-standing mystery has been the apparent absence of a key enzyme, dihydroneopterin aldolase, in the classical folate biosynthetic pathway of this organism. The discovery that a different enzyme, pyruvoyltetrahydropterin synthase, can produce the necessary substrate for the subsequent step in folate synthesis raises the question of whether this solution is unique to P. falciparum. Bioinformatic analyses suggest otherwise and indicate that an alternative route to folate could be widespread among diverse microorganisms and could be a target for novel drugs.  相似文献   

7.
8.
Following the Tocquevillian tradition and driven by a neoliberal concern, many China scholars interpret the rise of philanthropy in contemporary China as a sign of the growing “civil society” that will help to democratize the country and improve its citizens’ social well-being. However, this paper shows that philanthropy in the Chinese context works to reproduce social inequalities between philanthropists and the subjects they claim to help. My ethnography focuses on philanthropic activities in a state-run orphanage in southeastern China. In these activities, characterized primarily by donations and volunteer work, middle- and upper-class philanthropists label orphans as “the unfortunate” or even “the abnormal unfortunate” to create a clear-cut “they/unfortunate–we/fortunate” dichotomy that stigmatizes these children. Furthermore, they utilize this dichotomy as a tool to transmit class consciousness to their own children, “touristify” the orphanage, and even exploit the orphans for marketing or commercial purposes. The pragmatic rationale reflected in these representations and practices also provides an alternative to the current anthropological studies on humanitarianism, which have mostly focused on religious, ethical and moral motivations among philanthropic agencies.  相似文献   

9.
Gentle A  McBrien NA 《Cytokine》2002,18(6):344-348
AIMS: Studies in avian models of myopia have shown that refractive error development can be influenced by exogenously delivered fibroblast growth factor (FGF)-2. The present study sought to determine whether endogenous FGF-2 was associated with retinoscleral signalling or scleral remodelling during changes in refractive error in a mammalian model of myopia. METHODS: Myopia was induced in tree shrews over a 5-day period. One group of animals was then allowed 3 days of recovery from the induced myopia. Endogenous levels of FGF-2 were measured in scleral and retinal homogenates using ELISA. Real-time PCR was used to investigate scleral FGF-2 and FGF receptor (FGFR)-1 mRNA expression. RESULTS: No difference in FGF-2 content was found in posterior scleral or retinal extracts of myopic eyes (scleral -4+/-9%, retinal +23+/-17%) or recovering eyes (scleral -10+/-18%, retinal +1+/-13%), when compared with contralateral control eyes. In addition, no significant changes were found in scleral FGF-2 mRNA expression in myopic or recovering eyes (+106+/-56% and +14+/-12% respectively, P=0.21). However, FGF-2 concentration was significantly higher in anterior, relative to posterior, scleral regions in all animals (1602+/-105 vs 1030+/-50pg/mg respectively P<0.001). Expression of scleral FGFR-1 mRNA was upregulated in myopic eyes (+186+/-32%, P=0.01) but returned to control eye levels during recovery (+63+/-20%). CONCLUSIONS: The findings indicate that alterations in endogenous retinal or scleral FGF-2 levels are not associated with changes in scleral remodelling in this mammalian model of myopia. However, the reversible changes found in FGFR-1 expression in the sclera of myopic eyes mean that an indirect role for FGF-2 in the control of scleral remodelling is implicated. The anteroposterior difference found in scleral FGF-2 concentration indicates a role for this cytokine in the control of normal scleral growth and development and, presumably, eye size.  相似文献   

10.
University–industry collaboration is an important factor in the bio-industrialization of developing countries: it is a considerable force in catalysing the development of novel bio-based industries that provide for human sustenance, and improvement of the quality of life.  相似文献   

11.
12.
Male dimorphism has been reported across different taxa and is usually expressed as the coexistence of a larger morph with exaggerated male traits and a smaller one with reduced traits. The evolution and maintenance of male dimorphism are still poorly understood for several of the species in which it has been observed. Here, we analyse male dimorphism in several species of reptile parasitic nematodes of the genus Spauligodon, in which a major male morph (exaggerated morph), which presents the traditional male morphological traits reported for this taxon, coexists with a minor morph with reduced morphological traits (i.e. reduced genital papillae) resembling more closely the males of the sister genus Skrjabinodon than Spauligodon major males. Because of the level of uncertainty in the results of ancestral state reconstruction, it is unclear if the existence of male dimorphism in this group represents independent instances of convergent evolution or an ancestral trait lost multiple times. Also, although the number of major males per host was positively correlated with the number of females, the same did not hold true for minor males, whose presence was not associated with any other ecological factor. Nevertheless, the existence of male dimorphism in Spauligodon nematodes is tentatively interpreted as resulting from alternative reproductive tactics, with differences in presence and number of individuals as indicators of differences in fitness, with the lower numbers of minor males per host likely maintained by negative frequency‐dependent selection.  相似文献   

13.
Converting cellulosic biomass to ethanol involves the enzymatic hydrolysis of cellulose and the fermentation of the resulting glucose. The yeast Saccharomyces cerevisiae is naturally ethanologenic, but lacks the enzymes necessary to degrade cellulose to glucose. Towards the goal of engineering S. cerevisiae for hydrolysis of and ethanol production from cellulose, 35 fungal β-glucosidases (BGL) from the BGL1 and BGL5 families were screened for their ability to be functionally expressed and displayed on the cell surface. Activity assays revealed that the BGL families had different substrate specificities, with only the BGL1s displaying activity on their natural substrate, cellobiose. However, growth on cellobiose showed no correlation between the specific growth rates, the final cell titer, and the level of BGL1 activity that was expressed. One of the BGLs that expressed the highest levels of cellobiase activity, Aspergillus niger BGL1 (Anig-Bgl101), was then used for further studies directed at developing an efficient cellobiose-fermenting strain. Expressing Anig-Bgl101 from a plasmid yielded higher ethanol levels when secreted into the medium rather than anchored to the cell surface. In contrast, ethanol yields from anchored and secreted Anig-Bgl101 were comparable when integrated on the chromosome. Flow cytometry analysis revealed that chromosomal integration of Anig-Bgl101 resulted in a higher percentage of the cell population that displayed the enzyme but with overall lower expression levels.  相似文献   

14.
One of the most frequently advanced explanations of the Maoists’ popularity in rural Nepal links dissatisfaction with the State to forms of consciousness and changes in expectations that are products and processes of development. Such theories often attribute popular support for the insurrection to frustrated desires stemming from “failed” or “incomplete” development. Against this, others suggest that it was the very “success” of empowerment programs which aimed to raise participants’ consciousness of oppression and its roots that inspired villagers to embrace revolutionary action. This paper argues that, despite their differences, both hypotheses reflect assumptions about gendered selfhood and political action that limit their recognition of what motivates Maoist sympathies. Extended research with women in Gorkha—a district where female support for the rebels is said to be especially strong—reveals that Gorkhali women’s support for the rebels is not inspired primarily by the desire for greater autonomy, choice or absolute liberation from social constraints, all of which ideals valorize a culturally specific vision of individual agency. Rather, women there report a sense of self that defines itself through social relations and commitments and which values the common good over individual self-interest, which they associate with an unjust state. The disjuncture between Gorkhali women’s own understandings of self and society and prevailing theories of what motivates people to rebel highlights the modernist assumptions that underlie—and potentially distort—otherwise diverse scholarly perspectives. Likewise, it implies that rebellions may be less about consciousness and more about morality than either “failed” or “successful” theories presume.  相似文献   

15.
16.
Parent-offspring conflict may arise because the lifetime reproductive success of the parent is more influenced by its life span than by reproductive success during a particular reproductive event, while the fitness of an offspring depends firstly on its own survival as a juvenile and only subsequently on its own reproductive success. The naive immune system of young animals may allow offspring to be much more affected by parasites than their parents, and thus cause an initial asymmetry in a potential parent-offspring conflict. We investigated this type of conflict by assessing the health status and the immune response of parent and offspring sand martins Riparia riparia infested with manipulated loads of ticks Ixodes lividus (nests either treated with pyrethrin, water, or just visited). The prevalence and the intensity of tick infestations differed among treatments, with low tick loads in nests with the pyrethrin treatment. Ticks reduced the reproductive success of the host and increased offspring wing length. Broods with ticks had higher leukocyte concentrations and concentrations of immunoglobulins. The concentration of immunoglobulins in nestlings was negatively related to brood size and nestling tarsus length. Nestlings receiving the control treatments had a positive association between wing length and the concentration of immunoglobulins and a negative association between tarsus length and immunoglobulins. In contrast, adult sand martins did not respond to the parasite treatment in terms of immune response. Hence, the naive immune system of nestlings may be the crucial factor causing the parent-offspring conflict over costs of parasitism to be resolved to the advantage of parents that may sacrifice nestlings in heavily parasitized nests. Received: 30 March 1998 / Accepted: 5 December 1998  相似文献   

17.
The human–animal bond is a relational theory which describes the dynamic between humans and nonhuman animals that satisfies needs in each for companionship and emotional support, framing companion animals as valued family members. Social workers have historically ignored the central role companion animals play in the lives of their clients, adopting an anthropocentric view underpinned by human rights and social justice. However, the need for companion animal-inclusive practice features in recent social work literature. As companion animals are intricately woven into the lives of their guardians, it follows that their inevitable death brings a profound sense of loss and thus an opportunity for social work intervention. The aim of this research was to see if there was a role for social work practitioners to support grieving animal companion guardians. Qualitative thematic analysis was performed on 218 candid online responses to an article on the topic of losing a companion animal, from which four major themes were identified: strength of the bond, anthropocentrically disenfranchised grief, anticipatory grief in the context of euthanasia, and the need for professional support. This analysis demonstrates the strength of the human– animal bond, illustrates how the dominant anthropocentric hegemony disenfranchises this variety of grief and loss, describes the experience of anticipatory grief in the context of euthanasia, and identifies the need for professional support. Implications for social work practice are identified, with opportunities for social workers to exchange their anthropocentric approach for a biocentric view, provide support to veterinarians and other professionals, and to work toward challenging the social constructs, which disenfranchise companion animal loss.  相似文献   

18.
Male sand lizards (Lacerta agilis) with a specific restriction fragment length polymorphism fragment in their major histocompatibility complex (MHC) genotype ('O-males') are more resistant to ectoparasites (a tick, Ixodes ricinus) than are males that lack this fragment ('NO-males'). However, emerging evidence suggests that such adaptive immune responses are costly, here manifested by reduced body condition and a compromised defence against secondary infections by haemoprotid parasites that use the ticks as vectors. Subsequent to tick encounter, O-males suffer from a higher leucocyte-erythrocyte ratio, and higher haemoprotid parasitaemia, in particular in relation to vector encounter rate. Furthermore, O-males (i.e. successful tick defenders) with more haemoprotid parasites remaining in their blood stream were in better body condition, whereas this did not apply in NO-males, demonstrating that the adaptive immunoreaction can--in the short term--be energetically even more costly than being moderately parasitized. In agreement with Zahavian handicap theory, O-males had a (marginally) higher reproductive success than males that lacked this fragment.  相似文献   

19.
Direct social contact and social interaction affect speech development in human infants and are required in order to maintain perceptual abilities; however the processes involved are still poorly known. In the present study, we tested the hypothesis that social segregation during development would prevent the proper development of a central auditory area, using a "classical" animal model of vocal development, a songbird. Based on our knowledge of European starling, we raised young female starlings with peers and only adult male tutors. This ensured that female would show neither social bond with nor vocal copying from males. Electrophysiological recordings performed when these females were adult revealed perceptual abnormalities: they presented a larger auditory area, a lower proportion of specialized neurons and a larger proportion of generalist sites than wild-caught females, whereas these characteristics were similar to those observed in socially deprived (physically separated) females. These results confirmed and added to earlier results for males, suggesting that the degree of perceptual deficiency reflects the degree of social separation. To our knowledge, this report constitutes the first evidence that social segregation can, as much as physical separation, alter the development of a central auditory area.  相似文献   

20.
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