Extracellular superoxide production, viability and redox poise in response to desiccation in recalcitrant Castanea sativa seeds

Reactive oxygen species (ROS) are implicated in seed death following dehydration in desiccation-intolerant 'recalcitrant' seeds. However, it is unknown if and how ROS are produced in the apoplast and if they play a role in stress signalling during desiccation. We studied intracellular damage and extracellular superoxide (O₂^·−) production upon desiccation in Castanea sativa seeds, mechanisms of O₂^·− production and the effect of exogenously supplied ROS. A transient increase in extracellular O₂^·− production by the embryonic axes preceded significant desiccation-induced viability loss. Thereafter, progressively more oxidizing intracellular conditions, as indicated by a significant shift in glutathione half-cell reduction potential, accompanied cell and axis death, coinciding with the disruption of nuclear membranes. Most hydrogen peroxide (H₂O₂)-dependent O₂^·− production was found in a cell wall fraction that contained extracellular peroxidases (ECPOX) with molecular masses of ∼50 kDa. Cinnamic acid was identified as a potential reductant required for ECPOX-mediated O₂^·− production. H₂O₂, applied exogenously to mimic the transient ROS burst at the onset of desiccation, counteracted viability loss of sub-lethally desiccation-stressed seeds and of excised embryonic axes grown in tissue culture. Hence, extracellular ROS produced by embryonic axes appear to be important signalling components involved in wound response, regeneration and growth.     

Hypomania: a transcultural perspective

This study examined the transcultural robustness of a screening instrument for hypomania, the Hypomania Checklist-32, first revised version (HCL-32 R1). It was carried out in 2606 patients from twelve countries in five geographic regions (Northern, Southern and Eastern Europe, South America and East Asia). In addition, GAMIAN Europe contributed data from its members. Exploratory and confirmatory factor analyses were used to examine the transregional stability of the measurement properties of the HCL-32 R1, including the influence of sex and age as covariates. Across cultures, a two-factor structure was confirmed: the first factor (F1) reflected the more positive aspects of hypomania (being more active, elated, self-confident, and cogni-tively enhanced); the second factor (F2) reflected the more negative aspects (being irritable, impulsive, careless, more substance use). The measurement properties of the HCL-32 R1 were largely invariant across cultures. Only few items showed transcultural differences in their relation to hypomania as measured by the test. F2 was higher among men and in more severe manic syndromes; F1 was highest in North and East Europe and lowest in South America. The scores decreased slightly with age. The frequency of the 32 items showed remarkable similarities across geographic areas, with two excep-tions: South Europeans had lower symptom frequencies in general and East Europeans higher rates of substance use. These findings support the interna-tional applicability of the HCL-32 R1 as a screening instrument for hypomania.     

Miscanthus×giganteus plant regeneration: effect of callus types,ages and culture methods on regeneration competence

The perennial rhizomatous grass, Miscanthus×giganteus is an ideal biomass crop due to its rapid vegetative growth and high biomass yield potential. As a naturally occurring sterile hybrid, M. ×giganteus must be propagated vegetatively by mechanically divided rhizomes or from micropropagated plantlets. Plant regeneration through somatic embryogenesis is a viable approach to achieve large‐scale production of plantlets in tissue culture. Effect of the callus types, ages and culture methods on the regeneration competence was studied to improve regeneration efficiency and shorten the period of tissue culture in M. ×giganteus. Shoot‐forming calli having a yellow or white compact callus with light‐green shoot‐like structures showed the highest regeneration frequency. Percentage of shoot‐forming callus induction from immature inflorescence explants was 41% on callus induction medium containing 13.6 μM 2,4‐d and 0.44 μM benzyladenine (BA). The use of a regeneration medium containing 1.3 μM NAA and 22 μM BA was effective at shortening the incubation period required for plantlet regeneration, with 69% of total regenerated plantlets obtained within 1 month of incubation on regeneration medium. Embryogenic‐like callus morphotype could maintain regeneration competency for up to 1 year as suspension cultures. Field grown regenerated plants showed normal phenotypic development with DNA content and plant heights comparable to rhizome propagated plants. Winter survival rates of the regenerated plants planted in 2006 and 2007 at the University of Illinois South Farm, Urbana‐Champaign, Illinois, were 78% and 56%, respectively.     

Survival of Colonizing Wolves in the Northern Rocky Mountains of the United States, 1982–2004

Abstract: After roughly a 60-year absence, wolves (Canis lupus) immigrated (1979) and were reintroduced (1995-1996) into the northern Rocky Mountains (NRM), USA, where wolves are protected under the Endangered Species Act. The wolf recovery goal is to restore an equitably distributed metapopulation of ≥30 breeding pairs and 300 wolves in Montana, Idaho, and Wyoming, while minimizing damage to livestock; ultimately, the objective is to establish state-managed conservation programs for wolf populations in NRM. Previously, wolves were eradicated from the NRM because of excessive human killing. We used Andersen–Gill hazard models to assess biological, habitat, and anthropogenic factors contributing to current wolf mortality risk and whether federal protection was adequate to provide acceptably low hazards. We radiocollared 711 wolves in Idaho, Montana, and Wyoming (e.g., NRM region of the United States) from 1982 to 2004 and recorded 363 mortalities. Overall, annual survival rate of wolves in the recovery areas was 0.750 (95% CI = 0.728-0.772), which is generally considered adequate for wolf population sustainability and thereby allowed the NRM wolf population to increase. Contrary to our prediction, wolf mortality risk was higher in the northwest Montana (NWMT) recovery area, likely due to less abundant public land being secure wolf habitat compared to other recovery areas. In contrast, lower hazards in the Greater Yellowstone Area (GYA) and central Idaho (CID) likely were due to larger core areas that offered stronger wolf protection. We also found that wolves collared for damage management purposes (targeted sample) had substantially lower survival than those collared for monitoring purposes (representative sample) because most mortality was due to human factors (e.g., illegal take, control). This difference in survival underscores the importance of human-caused mortality in this recovering NRM population. Other factors contributing to increased mortality risk were pup and yearling age class, or dispersing status, which was related to younger age cohorts. When we included habitat variables in our analysis, we found that wolves having abundant agricultural and private land as well as livestock in their territory had higher mortality risk. Wolf survival was higher in areas with increased wolf density, implying that secure core habitat, particularly in GYA and CID, is important for wolf protection. We failed to detect changes in wolf hazards according to either gender or season. Maintaining wolves in NWMT will require greater attention to human harvest, conflict resolution, and illegal mortality than in either CID or GYA; however, if human access increases in the future in either of the latter 2 areas hazards to wolves also may increase. Indeed, because overall suitable habitat is more fragmented and the NRM has higher human access than many places where wolves roam freely and are subject to harvest (e.g., Canada and AK), monitoring of wolf vital rates, along with concomitant conservation and management strategies directed at wolves, their habitat, and humans, will be important for ensuring long-term viability of wolves in the region.     

Land Use and Small Mammal Predation Effects on Shortgrass Prairie Birds

ABSTRACT Grassland birds endemic to the central shortgrass prairie ecoregion of the United States have experienced steep and widespread declines over the last 3 decades, and factors influencing reproductive success have been implicated. Nest predation is the major cause of nest failure in passerines, and nesting success for some shortgrass prairie birds is exceptionally low. The 3 primary land uses in the central shortgrass prairie ecoregion are native shortgrass prairie rangeland (62%), irrigated and nonirrigated cropland (29%), and Conservation Reserve Program (CRP, 8%). Because shortgrass–cropland edges and CRP may alter the community of small mammal predators of grassland bird nests, I sampled multiple sites on and near the Pawnee National Grasslands in northeast Colorado, USA, to evaluate 1) whether small mammal species richness and densities were greater in CRP fields and shortgrass prairie–cropland edges compared to shortgrass prairie habitats, and 2) whether daily survival probabilities of ground-nesting grassland bird nests were negatively correlated with densities of small mammals. Small mammal species richness and densities, estimated using trapping webs, were generally greater along edges and on CRP sites compared to shortgrass sites. Vegetation did not differ among edges and shortgrass sites but did differ among CRP and shortgrass sites. Daily survival probabilities of artificial nests at edge and CRP sites and natural nests at edge sites did not differ from shortgrass sites, and for natural nests small mammal densities did not affect nest survival. However, estimated daily survival probability of artificial nests was inversely proportional to thirteen-lined ground squirrel (Spermophilus tridecemlineatus) densities. In conclusion, these data suggest that although land-use patterns on the shortgrass prairie area in my study have substantial effects on the small mammal community, insufficient data existed to determine whether land-use patterns or small mammal density were affecting grassland bird nest survival. These findings will be useful to managers for predicting the effects of land-use changes in the shortgrass prairie on small mammal communities and avian nest success.     

Science and Values Influencing Predator Control for Alaska Moose Management

ABSTRACT We encourage informed and transparent decision-making processes concerning the recently expanded programs in Alaska, USA, to reduce predation on moose (Alces alces). The decision whether to implement predator control ultimately concerns what society should value; therefore, policymakers, not objective biologists, play a leadership role. From a management and scientific standpoint, biological support for these predator-control programs requires convincing evidence that 1) predators kill substantial numbers of moose that would otherwise mostly live and be available for harvest, 2) low predation can facilitate reliably higher harvests of moose, 3) given less predation, habitats can sustain more moose and be protected from too many moose, and 4) sustainable populations of Alaska's brown bears (Ursus arctos), black bears (Ursus americanus), and wolves (Canis lupus) will exist in and out of control areas. We reviewed 10 moose mortality studies, 36 case histories, 10 manipulative studies, 15 moose nutrition studies, and 3 recent successful uses of nutrition-based management to harvest excess female moose. Results of these studies support application of long-term, substantial predator control for increasing yield of moose in these simple systems where moose are a primary prey of 3 effective predators. We found no substantive, contradictory results in these systems. However, to identify and administer feasible moose population objectives, recently established moose nutritional indices must be monitored, and regulatory bodies must accept nutrition-based management. In addition, the efficacy of techniques to reduce bear predation requires further study. Predicting precise results of predator control on subsequent harvest of moose will continue to be problematic because of a diversity of changing interactions among biological, environmental, and practical factors. In Alaska, the governor has the prerogative to influence regulations on predator control by appointing members to the Board of Game. At least annually, the Board of Game hears a wide spectrum of public opinions opposing and favoring predator control. We summarized these opinions as well as the societal and cultural values and expectations that are often the primary basis for debates. Advocates on both sides of the debate suggest they hold the higher conservation ethic, and both sides provide biased science. We recommend a more constructive and credible dialogue that focuses openly on values rather than on biased science and fabricated conspiracies. To be credible and to add substance in this divisive political arena, biologists must be well informed and provide complete information in an unbiased and respectful manner without exaggeration.     

Strong genetic cohesiveness between Italy and North Africa in four butterfly species

The sea acts as an effective dispersal barrier for most terrestrial animal species. Narrow sea straits, therefore, often represent areas where species are able to disperse from one land mass to another. In the Mediterranean Sea, the narrowest connecting points between North Africa and Europe are the Strait of Gibraltar and the Strait of Sicily. In the past, climatic oscillations caused changing sea levels and thus influenced the permeability of these sea straits. We analysed the genetic structure of four butterfly species that all occur on both sides of the Strait of Sicily. In all four species, we observed a lack of genetic differentiation between the populations of North Africa and those of Italy. Species distribution models support the strong cohesiveness in that they show a largely continuous glacial distribution over Italy and North Africa. The data obtained reveal that there was a large exchange of individuals between Italy and the eastern Maghreb during the last ice age. This might not only be the case for the species under investigation in the present study, but also might represent a more general pattern for mobile thermophilic western Palearctic species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 818–830.     

Mandibular biomechanics of Crocuta crocuta,Canis lupus,and the late Miocene Dinocrocuta gigantea (Carnivora,Mammalia)

The relative simplicity of the mandible and its functional integration with the upper dentition in carnivorans makes it an ideal subject for functional morphological studies. To compare the mandibular biomechanics of two convergently evolved bone‐cracking ecomorphologies, we used finite element modelling to analyse mandibular corpus stress. The bone‐cracking spotted hyena Crocuta crocuta was used as a living analogue to the late Miocene percrocutid Dinocrocuta gigantea, using the grey wolf Canis lupus as a molar bone‐crushing outgroup. Mandibular stress values during p3, p4, and m1 tooth biting are found to be lowest in Cr. crocuta, and elevated in both Ca. lupus and D. gigantea. However, the stress‐dissipation patterns of the pre‐m1 corpus are similar between Cr. crocuta and D. gigantea. Lastly, D. gigantea has a relatively weaker corpus at the post‐m1 position than either Cr. crocuta or Ca. lupus. These findings suggest that even though stress patterns are similar amongst the bone‐cracking ecomorphs, the extinct D. gigantea had a weaker mandibular structure when performing a comparable bone‐cracking task as in Cr. crocuta because of its slender post‐m1 corpus. Ontogeny could potentially play an important role in strengthening the post‐m1 corpus by growth in the dorsoventral axis, and continuous increase in biting performance through adulthood in living Cr. crocuta suggests the possibility of a relatively more delayed development to full bone‐cracking capability in D. gigantea. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 158 , 683–696.     

Inter‐regional comparison of land‐use effects on stream metabolism

1. Rates of whole‐system metabolism (production and respiration) are fundamental indicators of ecosystem structure and function. Although first‐order, proximal controls are well understood, assessments of the interactions between proximal controls and distal controls, such as land use and geographic region, are lacking. Thus, the influence of land use on stream metabolism across geographic regions is unknown. Further, there is limited understanding of how land use may alter variability in ecosystem metabolism across regions. 2. Stream metabolism was measured in nine streams in each of eight regions (n = 72) across the United States and Puerto Rico. In each region, three streams were selected from a range of three land uses: agriculturally influenced, urban‐influenced, and reference streams. Stream metabolism was estimated from diel changes in dissolved oxygen concentrations in each stream reach with correction for reaeration and groundwater input. 3. Gross primary production (GPP) was highest in regions with little riparian vegetation (sagebrush steppe in Wyoming, desert shrub in Arizona/New Mexico) and lowest in forested regions (North Carolina, Oregon). In contrast, ecosystem respiration (ER) varied both within and among regions. Reference streams had significantly lower rates of GPP than urban or agriculturally influenced streams. 4. GPP was positively correlated with photosynthetically active radiation and autotrophic biomass. Multiple regression models compared using Akaike’s information criterion (AIC) indicated GPP increased with water column ammonium and the fraction of the catchment in urban and reference land‐use categories. Multiple regression models also identified velocity, temperature, nitrate, ammonium, dissolved organic carbon, GPP, coarse benthic organic matter, fine benthic organic matter and the fraction of all land‐use categories in the catchment as regulators of ER. 5. Structural equation modelling indicated significant distal as well as proximal control pathways including a direct effect of land‐use on GPP as well as SRP, DIN, and PAR effects on GPP; GPP effects on autotrophic biomass, organic matter, and ER; and organic matter effects on ER. 6. Overall, consideration of the data separated by land‐use categories showed reduced inter‐regional variability in rates of metabolism, indicating that the influence of agricultural and urban land use can obscure regional differences in stream metabolism.     

Invalidation of Hyperamoeba by Transferring its Species to Other Genera of Myxogastria

ABSTRACT. The genus Hyperamoeba Alexeieff, 1923 was established to accommodate an aerobic amoeba exhibiting three life stages—amoeba, flagellate, and cyst. As more species/strains were isolated, it became increasingly evident from small subunit (SSU) gene phylogenies and ultrastructure that Hyperamoeba is polyphyletic and its species occupy different positions within the class Myxogastria. To pinpoint Hyperamoeba strains within other myxogastrid genera we aligned numerous myxogastrid sequences: whole small subunit ribosomal (SSU or 18S rRNA) gene for 50 dark‐spored (i.e. Stemonitida and Physarida) Myxogastria (including a new “Hyperamoeba”/Didymium sequence) and a ～400‐bp SSU fragment for 147 isolates assigned to 10 genera of the order Physarida. Phylogenetic analyses show unambiguously that the type species Hyperamoeba flagellata is a Physarum (Physarum flagellatum comb. nov.) as it nests among other Physarum species as robust sister to Physarum didermoides. Our trees also allow the following allocations: five Hyperamoeba strains to the genus Stemonitis; Hyperamoeba dachnaya, Pseudodidymium cryptomastigophorum, and three other Hyperamoeba strains to the genus Didymium; and two further Hyperamoeba strains to the family Physaridae. We therefore abandon the polyphyletic and redundant genus Hyperamoeba. We discuss the implications for the ecology and evolution of Myxogastria, whose amoeboflagellates are more widespread than previous inventories supposed, being now found in freshwater and even marine environments.