Three decades of stranding data reveal insights into endangered hawksbill sea turtles in Hawai‘i&dagger

Hawksbill sea turtles Eretmochelys imbricata inhabiting the Hawaiian Islands are extremely rare and listed as endangered under the US Endangered Species Act. The paucity of data on basic hawksbill ecology continues to hinder effective management of the species. We analyzed stranding data collected between 1984 and 2018 to gain insights into the distribution, demography, and conservation challenges facing hawksbills in Hawai‘i. In doing so, we present a comprehensive description of the population across developmental stages and rank threats that may be impeding their successful recovery. Over the >30 yr data set, we recorded a total of only 111 juvenile and adult hawksbill stranding events. Interactions with nearshore recreational fishing gear were documented for a large proportion (48.6%) of stranding events in the Hawaiian Islands, identifying this as the primary management challenge for the species. Stranding events were biased towards females (female to male sex ratio of 4.8:1.0), which may be indicative of the population as a whole. Even though the majority of hawksbills nest on the islands of Hawai‘i Moloka‘i, and Maui, the greatest number of juvenile to adult strandings was found to be on the island of Oahu (n = 47). Temporal distribution of the majority of adult hawksbill strandings (72.2%) occurred during a 4 mo period between June and September. We discuss these and other findings that help identify future research and conservation efforts to mitigate anthropogenic threats in Hawai‘i for this enigmatic population.

Ensemble Random Forests as a tool for modeling rare occurrences

Relative to target species, priority conservation species occur rarely in fishery interactions, resulting in imbalanced, overdispersed data. We present Ensemble Random Forests (ERFs) as an intuitive extension of the Random Forest algorithm to handle rare event bias. Each Random Forest receives individual stratified randomly sampled training/test sets, then down-samples the majority class for each decision tree. Results are averaged across Random Forests to generate an ensemble prediction. Through simulation, we show that ERFs outperform Random Forest with and without down-sampling, as well as with the synthetic minority over-sampling technique, for highly class imbalanced to balanced datasets. Spatial covariance greatly impacts ERFs’ perceived performance, as shown through simulation and case studies. In case studies from the Hawaii deep-set longline fishery, giant manta ray Mobula birostris syn. Manta birostris and scalloped hammerhead Sphyrna lewini presence had high spatial covariance and high model test performance, while false killer whale Pseudorca crassidens had low spatial covariance and low model test performance. Overall, we find ERFs have 4 advantages: (1) reduced successive partitioning effects; (2) prediction uncertainty propagation; (3) better accounting for interacting covariates through balancing; and (4) minimization of false positives, as the majority of Random Forests within the ensemble vote correctly. As ERFs can readily mitigate rare event bias without requiring large presence sample sizes or imparting considerable balancing bias, they are likely to be a valuable tool in bycatch and species distribution modeling, as well as spatial conservation planning, especially for protected species where presence can be rare.

Compromised Metabolic Reprogramming Is an Early Indicator of CD8+ T Cell Dysfunction during Chronic Mycobacterium tuberculosis Infection

The immunometabolic mechanisms underlying suboptimal T cell immunity in tuberculosis remain undefined. Here, we examine how chronic Mycobacterium tuberculosis (Mtb) and M. bovis BCG infections rewire metabolic circuits and alter effector functions in lung CD8⁺ T cells. As Mtb infection progresses, mitochondrial metabolism deteriorates in CD8⁺ T cells, resulting in an increased dependency on glycolysis that potentiates inflammatory cytokine production. Over time, these cells develop bioenergetic deficiencies that reflect metabolic “quiescence.” This bioenergetic signature coincides with increased mitochondrial dysfunction and inhibitory receptor expression and was not observed in BCG infection. Remarkably, the Mtb-triggered decline in T cell bioenergetics can be reinvigorated by metformin, giving rise to an Mtb-specific CD8⁺ T cell population with improved metabolism. These findings provide insights into Mtb pathogenesis whereby glycolytic reprogramming and compromised mitochondrial function contribute to the breakdown of CD8⁺ T cell immunity during chronic disease, highlighting opportunities to reinvigorate immunity with metabolically targeted pharmacologic agents.

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T cells from Mtb and BCG infections have unique metabolic and functional signatures

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Mitochondrial metabolism deteriorates in effector T cells as Mtb infection persists

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Metformin rejuvenates mitochondrial metabolism in T cells from Mtb-infected mice

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The breakdown of Mtb immunity during chronic disease is linked to immunometabolism

Higher respiratory rates and improved creatine stimulation in brain mitochondria isolated with anti-oxidants

We tested the effect of an anti-oxidant mixture on respiration in isolated rat brain mitochondria. Mitochondria were isolated in mannitol/sucrose/EGTA/BSA +/- SCAVEGR anti-oxidants (SOD, catalase, vitamin E, vitamin E acetate, and glutathione reduced). TBARS were reduced by greater than 40% with SCAVEGR. Respiration driven by ADP showed a two-fold higher V(max) and a 15% higher respiratory control ratio when mitochondria were prepared with SCAVEGR. SCAVEGR also stabilized the octameric state of mitochondrial creatine kinase and thus improved creatine-stimulated respiration. These results suggest that significant improvements in brain mitochondrial function are obtained by isolation in the presence of an anti-oxidants mixture.

The benefits of clomipramine-fluoxetine combination in obsessive compulsive disorder

We report the benefits of clomipramine-fluoxetine combination in four cases of severe obsessive compulsive disorder. In two cases, the combination was effective when either drug used singly was ineffective. In the other two cases, fluoxetine adjunct produced benefits with no additional side effects.