Experimental and Computational Studies of the Diastereoselective Alkylations of 3‑Substituted γ‑Sultams

We report that chiral 3-substituted γ-sultam α-carbanions undergo diastereoselective alkylation reactions with alkyl halides to predominantly produce <i>trans</i>-3,5-disubstituted γ-sultam products. Quantum mechanical calculations provided a stereoelectronic rationale for the observed diastereoselectivity

Comparative ecophysiology of a critically endangered (CR) ectotherm: Implications for conservation management

<div><p>Captive breeding is a vital conservation tool for many endangered species programs. It is often a last resort when wild animal population numbers drop to below critical minimums for natural reproduction. However, critical ecophysiological information of wild counterparts may not be well documented or understood, leading to years of minimal breeding successes. We collected endocrine and associated ecological data on a critically endangered ectotherm concurrently in the wild and in captivity over several years. We tracked plasma concentrations of steroid stress and reproductive hormones, body condition, activity, and environmental parameters in three populations (one wild and two geographically distinct captive) of ploughshare tortoise (<i>Astrochelys yniphora</i>). Hormone profiles along with environmental and behavioral data are presented and compared. We show that animals have particular seasonal environmental requirements that can affect annual reproduction, captivity affects reproductive state, and sociality may be required at certain times of the year for breeding to be successful. Our data suggest that changes in climatic conditions experienced by individuals, either due to decades-long shifts or hemispheric differences when translocated from their native range, can stifle breeding success for several years while the animals physiologically acclimatize. We also found that captivity affects stress (plasma corticosterone) and body condition of adults and juveniles differently and seasonally. Our results indicate that phenotypic plasticity in reproduction and behavior is related to environmental cues in long-lived ectotherms, and detailed ecophysiological data should be used when establishing and improving captive husbandry conditions for conservation breeding programs. Further, considering the recent revelation of this tortoises’ possible extirpation from the wild, these data are critically opportune and may be key to the survival of this species.</p></div

Monthly body condition scores for <i>Astrochelys yniphora</i> populations.

<p>Mean monthly body condition score (BCS; weight/length residuals) changes by month of adult male and female <i>A</i>. <i>yniphora</i> from three populations (wild, Madagascar captive, and U.S. captive). Error bars represent 1 SE.</p

Hormone concentrations in sub-adult <i>Astrochelys yniphora</i> populations.

<p>Mean monthly steroid hormone concentrations in sub-adult <i>A</i>. <i>yniphora</i> from all sample populations combined. Smoothing lines included for ease of interpretation, however, no differences between months were significant. Number of samples collected is listed with the number of individuals represented in parentheticals. Error bars represent 1 SE.</p

Hormone concentrations in female <i>Astrochelys yniphora</i> populations.

<p>Mean monthly steroid hormone concentrations in adult female <i>A</i>. <i>yniphora</i> from three sample populations (wild, Madagascar captive, and U.S. captive), collected in 2013 through 2015. Number of samples collected from each population is listed with the number of individuals represented in parentheticals. Error bars represent 1 SE.</p

Hormone, morphometric, and environmental data relating to <i>Astrochelys yniphora</i>.

<p>Hormone, morphometric, and environmental data relating to <i>Astrochelys yniphora</i>.</p

Observed activity of <i>Astrochelys yniphora</i> populations.

<p>Percent of total observed activity of <i>A</i>. <i>yniphora</i> from three populations (wild, Madagascar Captive, and U.S. Captive).</p

Stress hormones in <i>Astrochelys yniphora</i> populations.

<p>Summary of mean circulating corticosterone concentrations in male (M), female (F), and sub-adult (SA) <i>A</i>. <i>yniphora</i> from the wild, a captive population near native range (Madagascar Captive), and a small outgroup, captive population in the U.S from 2013–2015. Error bars = 1SE.</p

Environmental factors associated with <i>Astrochelys yniphora</i>.

<p>Mean air temperature, ground temperature, and ground humidity by month and sex at <i>A</i>. <i>yniphora</i> locations between the two Madagascar populations from 2012–2015.</p

Wild <i>Astrochelys yniphora</i> in its native habitats.

<p>This “golden tortoise” is near extinct in the wild (EW) due to wildlife smugglers.</p