Comparison of Vegetation and CO2 Dynamics Between a Restored Cut‐Away Peatland and a Pristine Fen: Evaluation of the Restoration Success

We studied the restoration success of a cut‐away peatland 10 years after restoration by comparing the vegetation and CO₂ dynamics with those of a pristine peatland of similar nutrition level and climate. Vegetation and CO₂ dynamics were monitored during one growing season. We used DCA (detrended correspondence analysis) and diversity indices to study the vegetation composition within and between the sites, and non‐linear regression models to estimate the seasonal CO₂ fluxes and balances of the sites. Based on both DCA and diversity indices, the study plots in the restored site differed more in the vegetation composition than the study plots in the pristine site. The variation in the CO₂ fluxes and balance was greater in the restored than in the pristine site, resulting from the heterogeneous vegetation in the restored site. The seasonal net CO₂ balance was positive (sink) at both sites, the restored site binding on average 500 ± 410 g CO₂/m² and the pristine site 390 ± 265 g CO₂/m² (statistically not different, p = 0.575). The results indicate that the restoration of the vegetation composition is still incomplete but the vegetation coverage is sufficient for the restored site to function as a sink of atmospheric CO₂.     

Genetic Characteristics of Restored Elk Populations in Kentucky

Translocations are a common management practice to restore or augment populations. Understanding the genetic consequences of translocation efforts is important for the long-term health of restored populations. The restoration of elk (Cervus canadensis) to Kentucky, USA, included source stocks from 6 western states, which were released at 8 sites in southeastern Kentucky during 1997–2002. We assessed genetic diversity in restored herds and compared genetic similarity to source stocks based on 15 microsatellite DNA loci. Genetic variation in the restored populations was comparable to source stocks ( allelic richness = 3.52 and 3.50; expected heterozygosity = 0.665 and 0.661 for restored and source, respectively). Genetic differentiation among all source and restored populations ranged from 0.000 to 0.065 for pairwise F_ST and 0.034 to 0.161 for pairwise Nei's D_A. Pairwise genetic differentiation and Bayesian clustering revealed that stocks from Utah and North Dakota, USA, contributed most to restored populations. Other western stocks appeared less successful and were not detected with our data, though our sampling was not exhaustive. We also inferred natural movements of elk among release sites by the presence of multiple genetic stocks. The success of the elk restoration effort in Kentucky may be due, in part, to the large number of elk (n = 1,548), repeated releases, and use of diverse source stocks. Future restoration efforts for elk in the eastern United States should consider the use of multiple stock sources and a large number of individuals. In addition, preservation of genetic samples of founder stock will enable detailed monitoring in the future. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

Postrelease Dispersal of Reintroduced Elk (Cervus elaphus) in Ontario,Canada

We studied 2 years of postrelease telemetry data of elk (Cervus elaphus) translocated to their historic range limit in Ontario, Canada and sought to determine if postrelease movements were related to behavior, demography of released animals, or site–specific attributes such as length of holding period. During 1998–2004 we radio‐tracked 341 elk in 10 release groups via ground and aerial telemetry and monitored movement patterns relative to gender, age, and pre‐release holding period (4–112 days). We found that elk that were held for short periods prior to release (4–11 days) moved longer distances than those subject to extended conditioning (17–112 days), suggesting that an extended conditioning period is beneficial from the standpoint of promoting philopatry. When all elk were pooled by sex and age class, male calves remained in closer proximity (8.0 ± 13.2 km) to release sites than adult females (19.1 ± 20.6 km), adult males (19.7 ± 15.1 km), and female calves (14.4 ± 20.4 km). Most calves dispersed in a southeasterly direction whereas adults tended to travel southwest. Our results reveal that elk movement characteristics are influenced by factors such as release protocol and group demographics; these findings provide further insight regarding appropriate release methods for restoring natural populations near their historical range limit.     

Restoring the endangered oyster mussel (Epioblasma capsaeformis) to the upper Clinch River,Virginia: an evaluation of population restoration techniques

From 2005 to 2011, the federally endangered freshwater mussel Epioblasma capsaeformis (oyster mussel) was reintroduced at three sites in the upper Clinch River, Virginia, using four release techniques. These release techniques were (1) translocation of adults (site 1, n = 1418), (2) release of laboratory‐propagated sub‐adults (site 1, n = 2851), (3) release of 8‐week‐old laboratory‐propagated juveniles (site 2, n = 9501), and (4) release of artificially infested host fishes (site 3, n = 1116 host fishes). These restoration efforts provided a unique research opportunity to compare the effectiveness of techniques used to reestablish populations of extirpated and declining species. We evaluated the relative success of these four population restoration approaches via monitoring at each release site (2011–2012) using systematic 0.25‐m² quadrat sampling to estimate abundance and post‐release survival. Abundances of translocated adult and laboratory‐propagated sub‐adult E. capsaeformis at site 1 ranged 577–645 and 1678–1700 individuals, respectively, signifying successful settlement and high post‐release survival. Two untagged individuals (29.1 and 27.3 mm) were observed, indicating that recruitment is occurring at site 1. No E. capsaeformis were found at sites where 8‐week‐old laboratory‐propagated juveniles (site 2) and artificially infested host fishes (site 3) were released. Our results indicate that translocations of adults and releases of laboratory‐propagated sub‐adults were the most effective population restoration techniques for E. capsaeformis. We recommend that restoration efforts focus on the release of larger (>20 mm) individuals to accelerate augmenting and reintroducing populations and increase the probability for recovery of imperiled mussels.     

D2 receptor-mediated inhibition of dopamine release in the rat striatum in vitro is modulated by CB1 receptors: studies using fast cyclic voltammetry

Cannabinoid CB₁ receptors are highly expressed in the striatum where they are known to be co‐localized with dopamine D₂ receptors. There is now strong evidence that cannabinoids modulate dopamine release in the brain. Using fast cyclic voltammetry, single pulse stimulation (0.1 ms; 10 V) was applied every 5 min and peak dopamine release was measured with a carbon fibre microelectrode. Application of the D₂ receptor agonist, quinpirole, inhibited single pulse dopamine overflow in a concentration‐dependent manner (IC₅₀: 3.25 × 10^?8 M). The CB₁ receptor agonist WIN55212‐2 (WIN; 1 μM) had no effect on single pulse dopamine release (93.9 ± 6.6% at 60 min, n = 5) but attenuated the inhibitory effect of quinpirole (30 nM; quinpirole 39.0 ± 4.2% vs. quinpirole + WIN, 48.2 ± 3.7%, n = 5, p < 0.05). This affect was antagonized by the CB₁ receptor anatgonist [N‐(Piperidin‐1‐yl)‐5‐(4‐iodophenyl)‐1‐(2,4‐dichlorophenyl)‐4‐methyl‐1H‐pyrazole‐3‐carboxamide] (AM‐251, 1 μM). Dopamine release evoked by four pulses delivered at 1 Hz (4P1Hz) and 10 pulses delivered at 5 Hz (10P5Hz) was significantly inhibited by WIN [72.3 ± 7.9% control (peak 4 to 1 ratio measurement) and 66.9 ± 3.8% control (area under the curve measurement), respectively, p < 0.05; n = 6 for both]. Prior perfusion of WIN significantly attenuated the effects of quinpirole on multiple pulse‐evoked dopamine release (4P1Hz: quinpirole, 28.4 ± 4.8% vs. WIN + quinpirole, 52.3 ± 1.2%; 10P5Hz: quinpirole, 29.5 ± 1.3% vs. WIN + quinpirole, 59.4 ±7.1%; p < 0.05 for both; n = 6). These effects were also antagonized by AM‐251 (1 μM). This is the first report demonstrating a functional, antagonistic interaction between CB₁ receptors and D₂ autoreceptors in regulating rat striatal dopamine release.     

Home range, movement, and site fidelity of translocated northern bobwhite (Colinus virginianus) in southwest Georgia, USA

During 1997 and 1998, we compared home range, movement, and site fidelity characteristics of translocated wild northern bobwhite (Colinus virginianus) to resident birds using radiotelemetry. We captured wild bobwhites (n=74) in southwest Georgia, USA just before the breeding season and relocated them (>1.6 km from capture sites) to sites nearby where previous density estimates revealed that populations were low compared to surrounding areas. Translocated birds were equipped with radiotransmitters and released in groups of 8 to 12. Resident birds (n=166) were also captured and simultaneously monitored via radiotelemetry. We found no difference in home range size (F ₁=0.08, P=0.78), mean daily movements (F ₁=0.04, P=0.84), or distance moved from trap or release sites to arithmetic centers of home ranges (F ₁=1.58, P=0.21) between translocated and resident bobwhites. These results suggest that translocating wild bobwhites over relatively short distances into suitable habitat does not negatively influence bobwhite movement and renders site fidelity as reasonable. Therefore, translocation of wild bobwhites before breeding season can result in enhanced numbers of adult breeders in a target location and potentially augments fall populations via reproductive yield.     

Population genetic structure and comparative diversity of smallmouth bass Micropterus dolomieu: congruent patterns from two genomes

Genetic diversity and divergence patterns of smallmouth bass Micropterus dolomieu spawning groups are analysed across its northern native range with mtDNA cytochrome b gene sequences and eight unlinked nuclear DNA microsatellite loci. Results reveal high levels of genetic variability and significant differences in allelic representation among populations (mtDNA: mean ± s.e ., H_D = 0·50 ± 0·06, mean ± s.e ., θ_ST = 0·41 ± 0·02 and microsatellites: mean ± s.e . H_O = 0·46 ± 0·03, mean ± s.e . θ_ST = 0·25 ± 0·01). The distributions of 28 variant mtDNA haplotypes, which differ by an average of 3·94 nucleotides (range = 1–8), denote divergent representation among geographic areas. Microsatellite data support nine primary population groups, whose high self‐assignment probabilities likewise display marked divergence. Genetic patterns demonstrate: (1) high genetic diversity in both genomes, (2) significant divergence among populations, probably resulting from natal site homing and low lifetime migration, (3) support for three post‐glacial refugia that variously contributed to the current northern populations, which remain evident today despite waterway connectivity and (4) a weak yet significant genetic isolation by geographic distance pattern, indicating that other processes affect the differences among populations, such as territoriality and site fidelity.     

Genetic structure of California's elk: a legacy of extirpations,reintroductions, population expansions,and admixture

California, USA, is home to 3 subspecies of North American elk (Cervus canadensis): Roosevelt (C. c. roosevelti), Rocky Mountain (C. c. nelsoni), and tule (C. c. nannodes). Effective management requires a baseline understanding of each subspecies' range, admixture zones, and geographic patterns of genetic diversity. To address these questions, we genotyped 1,271 individual elk from California (n = 1,204) and reference populations of Rocky Mountain and Roosevelt elk from Nevada (n = 32) and Oregon (n = 35), USA. Using 19 polymorphic microsatellite loci, we detected admixture between Roosevelt and Rocky Mountain elk at a contact zone in northern California, and between Roosevelt and tule elk in north-coastal California and central-coastal California. We identified a genetically distinct population of Roosevelt elk in northwestern California, likely reflecting the remnant population that survived a large demographic decline from overhunting during the 1800s. Tule elk exhibited lower levels of heterozygosity (0.44 ± 0.03 [SD]) and allelic richness (2.9 ± 0.2) than Rocky Mountain (0.58 ± 0.05, 4.9 ± 0.4, respectively) and Roosevelt (0.50 ± 0.06, 4.4 ± 0.6, respectively) elk. Among tule elk populations, heterozygosity varied, with the lowest heterozygosity (0.23 ± 0.05) corresponding to the oldest enclosed herd used over the past century as a source of translocations. Among tule elk populations, genetic structure revealed several cases of successful and unsuccessful reintroduction or augmentation attempts. Results provide an essential baseline for future monitoring and decisions about harvest management, translocations to preserve genetic diversity, and landscape-level conservation planning to maintain, enhance, or obstruct connectivity of elk populations. Genome-wide sequencing and analyses are needed to quantify inbreeding absolutely and assess genetic load and the age of admixture where subspecies currently exchange genes.     

Ecological Correlates of Roost Fidelity in the Tent-Making Bat Artibeus watsoni

Roost switching is a common occurrence in bats, yet the causes and consequences of such behavior are poorly understood. In this study we explore the ecological correlates of roost fidelity in the tent‐making bat Artibeus watsoni, particularly focusing on the effect of sex, reproductive status, and roost availability using a three‐factor general linear model (GLM). We estimated roost fidelity of radio‐tracked individuals and found that the GLM was significant (R² = 0.72, F_10,34 = 8.91, p < 0.001). Significant interaction terms were observed for relative roost availability and sex (F_4,34 = 16.96, p < 0.001), and relative roost availability and reproductive status (F_6,34 = 7.62, p < 0.001), indicating that variation in roost fidelity among males and females, and among individuals under different breeding conditions, depended on relative roost availability at the site where they were radio‐tracked. Individuals in areas of high roost availability exhibited lower roost fidelity than those sampled in areas of lower roost availability. Females exhibited less roost fidelity than males for all roost availability categories, but the difference between males and females was only significant at high roost availability. The general pattern of decreased roost fidelity as roost availability increased was also prevalent among individuals in different breeding conditions. Additionally, satellite males exhibited higher roost fidelity than resident males in areas of low roost availability, and lactating females had higher roost fidelity than non‐breeding females in areas of medium roost availability. Our study thus demonstrates that sex, reproductive status, and roost availability all affect roost fidelity in the tent‐making bat A. watsoni, and also suggests that roost availability is the most important factor influencing roost fidelity in this bat, providing the first quantitative evidence that roost fidelity is correlated with roost abundance in a single species.     

Resilience of arboreal folivores to habitat damage by a severe tropical cyclone

Abstract Severe tropical cyclones greatly modify habitat of arboreal folivores by destroying forest canopy, reducing structure and complexity and defoliating remaining trees. We hypothesized that forest modification following severe Cyclone Larry would stress arboreal folivores of the Family Pseudocheiridae and be reflected in increased home ranges and a decrease in body condition. We conducted 19 pre‐cyclone and 24 post‐cyclone spotlighting surveys at a site with severe cyclone damage, and 18 post‐cyclone surveys at a site with minor damage. We detected a greater number of lemuroid, Hemibelideus lemuroides and green, Pseudochirops archeri, ringtail possums as these possums remained in the severely damaged canopy and forest edge. In contrast, Herbert River ringtail possums, Pseudochirulus herbertensis, were detected in smaller numbers. We radio‐tracked eight P. herbertensis before the cyclone, following two of these and nine new animals after the category 4 cyclone. No significant post‐cyclone alteration in home range area or span was recorded in data pooled across the two sites or in limited post‐cyclone data at the severely disturbed site, but a greater variability in home range was observed after cyclone (pooled across sites: 1.72 ± 0.77 ha; 197 ± 47 m) than before the cyclone (1.35 ± 0.30 ha; 196 ± 23 m). In contrast, pooled pre‐ and post‐cyclone home range areas and spans were larger at the severely‐disturbed site (2.08 ± 0.56 ha; 231 ± 32 m) than at the site with minor damage (0.68 ± 0.11 ha; 114 ± 25 m), suggesting resources were more widely spread at the former site. Post‐cyclone home ranges were also larger at the severely damaged site (severe: 3.33 ± 1.36 ha, n = 3; minor: 0.52 ± 0.07 ha, n = 4). Condition of P. herbertensis (mass/tail length) did not differ significantly pre‐ and post‐cyclone or between less and severely disturbed sites. These results and observations of breeding after cyclone suggest that possum populations may be resilient to severe cyclone damage under the relatively wet conditions experienced post‐Cyclone Larry.     

Site fidelity in temporally correlated environments enhances population persistence

Site fidelity, the phenomenon of remaining faithful to sites, often where an individual has bred successfully in the past, has important consequences for population dynamics. Previous results have shown that site fidelity results in a positive correlation between population density and fitness. Here, I build on this theme by incorporating site fidelity using the win‐stay : lose‐switch rule often seen among birds, i.e. individuals return to sites were they bred successfully in the past and vacate those where they have not. Results demonstrate that the combination of site fidelity and temporal autocorrelation in site quality can enhance the persistence of population networks, whereas either factor acting alone has little or no influence. Moreover, there is an abrupt threshold at moderate levels of temporal autocorrelation, ρ_time > 0.35–0.4, beyond which persistence time and the probability of surviving >500 years is greatly accelerated. These results suggest that temporal autocorrelation combined with appropriate behavioural responses may enhance population persistence.     

Field of Dreams: Restitution of Pollinator Services in Restored Bird‐Pollinated Plant Populations

Ecosystem functionality is an increasingly important objective of ecological restoration. Despite this, a few studies have rigorously assessed reproductive functionality within restored plant populations, and it is largely assumed that pollinators follow restoration of plant communities—“build it and they will come.” Here, we applied an ecological genetic approach to determine the impact of spatial separation on mating in Banksia menziesii (Proteaceae), a dominant bird‐pollinated species of Banksia woodlands of Western Australia. All plants at three post‐mining restored sites (n = 72 [13 years old], n = 21 [8 years old], and n = 20 [9 years old]), as well as a sample from an adjacent natural reference site (n = 42), were genotyped at nine microsatellite loci. Seed set, mating system parameters, realized pollen dispersal through the assignment of paternity to seed, and avian pollinator species composition, abundance and behavior, were assessed. All patches displayed equivalent heterozygosity (H_e = 0.53–0.59) and very weak genetic divergence (F_ST ≤ 0.01). Seed of plants within restored sites showed complete outcrossing and relatively high seed set, 26% of which were sired by pollen donors located beyond the local patch. Similar abundance and movement of nectar‐feeding birds was observed in restored and natural sites, despite lower bird species diversity in the restored site, where a smaller, less aggressive species was dominant. Our results demonstrate the restitution of wide outcrossing in these restored Banksia patches within an active mine‐site, and suggest that restored bird‐pollinated Banksia populations are resilient to human impacts, due largely to their generalist pollinator requirements and highly‐mobile avian pollinators.     

Low‐temperature physiology of climatically distinct south African populations of the biological control agent Neochetina eichhorniae

1. Neochetina eichhorniae is the most widely established biocontrol agent on water hyacinth populations around South Africa. However, some N. eichhorniae populations have failed to adequately control their host population, specifically those exposed to cold conditions.
2. The aim of this study was to determine whether two climatically distinct populations of N. eichhorniae in South Africa differ in their low‐temperature physiology, which tests whether local‐climate adaptation has occurred.
3. We estimated weevil CT_min, LLT₅₀, SCP, and SCP mortality using standard approaches. Contrary to expectation based on climatic thermal profiles at the two sites, weevils from the warm locality ((mean ± SE) CT_min = 5.0 °C ± 0.2, LLT₅₀ = ?11.3 °C ± 0.03, SCP = ?15.8 °C ± 0.6) were able to maintain activity and tolerate colder temperatures than the weevils from the colder site (CT_min = 6.0 °C ± 0.5, LLT₅₀ = ?10.1 °C ± 0.1, SCP = ?12.9 °C ± 0.8).
4. These contradictory outcomes are likely explained by the poor nutrient quality of the plants at the cold site, driving low‐temperature performance variation that overrode any macroclimate variation among sites. The cold site weevils may also have adapted to survive wide‐temperature variability, rather than perform well under very cold conditions. In contrast, the mass‐reared population of insects from the warm site has likely adapted to the consistent conditions that they experience over many years in confinement.

     

Spontaneous Return of Biodiversity in Restored Subtropical Thicket: Portulacaria afra as an Ecosystem Engineer

An accepted criterion for measuring the success of ecosystem restoration is the return of biodiversity relative to intact reference ecosystems. The emerging global carbon economy has made landscape‐scale restoration of severely degraded Portulacaria afra (spekboom)‐dominated subtropical thicket, by planting multiple rows of spekboom truncheons, a viable land‐use option. Although large amounts of carbon are sequestered when planting a monoculture of spekboom, it is unknown whether this is associated with the return of other thicket biodiversity components. We used available carbon stock data from degraded, restored, and intact stands at one site, and sampled carbon stocks at restored stands at another site in the same plant community. We also sampled plant community composition at both sites. The total carbon stock of the oldest (50 years) post‐restoration stand (250.8 ± 14 t C ha^?1) approximated that of intact stands (245 t C ha^?1) and we observed a general increase in carbon content with restoration age (71.4 ± 24 t C ha^?1 after 35 and 167.9 ± 20 t C ha^?1 after 50 years). A multiple correspondence analysis separated degraded stands from stands under restoration based on ground cover, floristic composition, and total carbon stock. Older post‐restoration and intact stands were clustered according to woody canopy recruit abundance. Our results suggest that spekboom is an ecosystem engineer that promotes spontaneous return of canopy species and other components of thicket biodiversity. The spekboom canopy creates a cooler micro‐climate and a dense litter layer, both likely to favor the recruitment of other canopy species.     

Habitat conditions at beaver settlement sites: implications for beaver restoration projects

Recognition that beavers are integral components of stream ecosystems has resulted in an increase in beaver‐mediated habitat restoration projects. Beaver restoration projects are frequently implemented in degraded stream systems with little or no beaver activity. However, selection of restoration sites is often based on habitat suitability research comparing well‐established beaver colonies to unoccupied stream sections or abandoned colonies. Because beavers dramatically alter areas they occupy, assessing habitat conditions at active colonies may over‐emphasize habitat characteristics that are modified by beaver activity. During 2015–2017, we conducted beaver activity surveys on streams in the upper Missouri River watershed in southwest Montana, United States, to investigate habitat selection by beavers starting new colonies in novel areas. We compared new colony locations in unmodified stream segments to unsettled segments to evaluate conditions that promoted colonization. Newly settled stream segments had relatively low gradients (β ± SE = ?0.72 ± 0.27), narrow channels (β = ?1.31 ± 0.46), high channel complexity (β = 0.76 ± 0.42), high canopy cover of woody riparian vegetation (β = 0.56 ± 0.21), and low‐lying areas directly adjacent to the stream (β = 0.36 ± 0.24), where β denotes covariate effect sizes. Habitat selection patterns differed between our new settlement site analysis and an analysis of occupied versus unoccupied stream segments, suggesting that assessing habitat suitability based on active colonies may result in misidentification of suitable site conditions for beaver restoration. Our research provides recommendations for beaver restoration practitioners to select restoration sites that will have the highest probability of successful colony establishment.     

Nest‐site fidelity in parental male bluegill Lepomis macrochirus: spatial patterns and the influence of prior mating success

A 4 year mark–recapture study examined the pattern of nesting site fidelity of parental‐type male bluegill Lepomis macrochirus. The study results indicated that iteroparous male L. macrochirus choose new nest sites near their own previously used sites. The scale of site fidelity varied, but generally males choose to renest within shoreline areas rather than specific or exact nest locations (94% within‐year, 86% among‐years). Iteroparous males also displayed no preference to nest in proximity to neighbouring males from previous colonies to suggest social fidelity. Contrary to expectation, manipulating males' reproductive success had no significant effect on the pattern or scale of male reproductive site fidelity.     

Within‐year movements and site fidelity of Purple Sandpipers during the nonbreeding season

ABSTRACT Although within‐year site fidelity to specific wintering sites allows shorebirds to use prior knowledge of resources and microhabitats, such fidelity may also make populations more vulnerable to extirpation in the event of increased predation pressure, habitat loss, or disturbance. In the eastern Atlantic, Purple Sandpipers (Calidris maritima) have been found to be highly faithful to specific sites in wintering areas. However, little is known about the use of wintering areas by these sandpipers along the coast of Maine. We quantified movements of 60 radio‐marked Purple Sandpipers in a bay near the mainland and on an offshore cluster of islands along the mid‐coast of Maine during two winters (2005–2006 and 2006–2007). Birds marked in early‐ and mid‐December remained until spring migration, with no evidence of onward migration. Mean maximum distances moved did not differ significantly between either males (8.6 ± 1.0 [SE] km; N= 30) and females (7.4 ± 0.8 km; N= 30) or juveniles (9.9 ± 1.6 km; N= 9) and adults (7.8 ± 1.1 km; N= 26). We also detected no monthly (January–May) differences in maximum distances moved. Sixty percent of marked individuals moved ≤5 km between the two most distant relocations and no birds moved >25 km during the 2‐ to 4‐month tracking period. We attribute the high site fidelity primarily to the plentiful prey base in the study area. During a 2‐d period with severe cold, feeding areas at locations protected from wave action became encased in ice and birds at these locations moved up to 10 km offshore to sites with less ice. Species with strong site fidelity, like wintering Purple Sandpipers, may be at higher risk in the event of large‐scale changes in their food base, increased predation pressure, habitat loss, or disturbance. However, the short‐distance movements made when intertidal feeding areas became encased in ice suggest that Purple Sandpipers could potentially move greater distances in response to changing conditions in their wintering areas.     

[125I]RTI-55 Binding to Cocaine-Sensitive Dopaminergic and Serotonergic Uptake Sites in the Human Brain

[¹²⁵I]RTI-55 is a newly synthesized cocaine congener that may offer advantages over other ligands previously used to examine cocaine binding sites. However, the in vitro pharmacological and anatomical characterization of [¹²⁵I]RTI-55 binding sites has not been previously performed in human brain. To determine the specificity, stability, and feasibility of [¹²⁵I]RTI-55 for use in radioligand binding assays in postmortem human tissue, a series of experiments were performed characterizing [¹²⁵I]RTI-55 binding sites in human brain using homogenized membrane preparations and quantitative autoradtography. Analysis of the association, dissociation, and saturation data favored two-phase processes. A curve-fitting analysis of the data derived in saturation experiments found a high-affinity site with K_D= 66 ± 35 pM and S_max= 13.2 ± 10.1 pmol/g of tissue and a low-affinity site with K_D= 1.52 ± 0.55 nM and B_max of 47.5 ± 11-2 pmol/g of tissue. Competition by ligands known to bind to the dopamine transporter showed a rank order of RTI-55 > GBR-12909 > mazindol > WIN 35428 > = methylphenidate > (?)-cocaine > buproprion > (±)-amphetamine. Binding to serotonergic sites was evaluated in the midbrain. Results of the saturation experiment performed autoradiographically in the midbrain showed a single site with K_D= 370 ± 84 pM. It appears that [¹²⁵I]RTI-55 should be useful in further studies of the regulation of cocaine binding sites using postmortem human specimens.     

Reproductive biology of albacore Thunnus alalunga

Reproductive variables in albacore Thunnus alalunga were evaluated by gonad histology in samples of 132 males (58–118 cm fork length, L_F) and 112 females (59–101 cm L_F) that were collected from the western North Pacific Ocean from 2001 to 2006. In the sex ratio examination, males greatly outnumbered females in large adult fish (L_F > 100 cm). Thunnus alalunga exhibited a protracted spawning period from March to September in the waters off eastern Taiwan and the Philippines, and the peak spawning activity occurred in March and April. Minimum sizes associated with the classification of mature fish were 78 and 83 cm L_F for males and females, respectively. In addition, the largest L_F of immature fish were 93 cm for males and 94 cm for females. The spawning frequency estimate in April was 1·7 days. Batch‐fecundity estimates of 21 females (89–99 cm L_F) ranged between 0·17 and 1·66 million eggs (mean ±s.d . = 0·94 ± 0·43). The relative fecundity estimates of the 21 females ranged between 9·2 and 92·4 oocytes g^?1 body mass (mean ±s.d . = 50·5 ± 22·8). The results presented in this study provide increased information regarding this species' reproductive‐related characteristics than are currently available in stock status determinations.     

Eddy covariance captures four‐phase crassulacean acid metabolism (CAM) gas exchange signature in Agave

Mass and energy fluxes were measured over a field of Agave tequilana in Mexico using eddy covariance (EC) methodology. Data were gathered over 252 d, including the transition from wet to dry periods. Net ecosystem exchanges (F_N,EC) displayed a crassulacean acid metabolism (CAM) rhythm that alternated from CO₂ sink at night to CO₂ source during the day, and partitioned canopy fluxes (F_A,EC) showed a characteristic four‐phase CO₂ exchange pattern. Results were cross‐validated against diel changes in titratable acidity, leaf‐unfurling rates, energy exchange fluxes and reported biomass yields. Projected carbon balance (g C m^?2 year^?1, mean ± 95% confidence interval) indicated the site was a net sink of ?333 ± 24, of which contributions from soil respiration were +692 ± 7, and F_A,EC was ?1025 ± 25. EC estimated biomass yield was 20.1 Mg (dry) ha^?1 year^?1. Average integrated daily F_A,EC was ?234 ± 5 mmol CO₂ m^?2 d^?1 and persisted almost unchanged after 70 d of drought conditions. Regression analyses were performed on the EC data to identify the best environmental predictors of F_A. Results suggest that the carbon acquisition strategy of Agave offers productivity and drought resilience advantages over conventional semi‐arid C3 and C4 bioenergy candidates.