Maya Kummrow

Vertebrate reproduction is controlled by 2 pituitary gonadotropin hormones (GtHs), FSH and LH, binding to gonadotropin hormone receptors (GtHRs) in gonadal tissues. All gnathostome vertebrates have been confirmed to possess at least 1 receptor for each GtH [LH receptor (LHR) and FSH receptor (FSHR)], except for species of the reptilian (nonavian sauropsidan) orders, such as lepidosauria, testudines, and crocodylia, which showed inexplicable reactions to heterologous amphibian, avian, and mammalian GtHs in early endocrinological studies. This study investigated the number and function of reptilian GtHRs. Genomic and transcriptomic analyses of selected tetrapod species now strongly suggest the inactivation of the LHR in all nonavian sauropsidans. This gene inactivation likely occurred independently in 3 branches of the sauropdisan clade, sparing only the avian class. Bioassays served to investigate the binding specificity of squamate, chelonian, crocodilian, avian, and mammalian GtHRs with their homologous and heterologous GtHs. The FSHR of a squamate lizard proved completely promiscuous to both its homologous GtHs, while the chelonian FSHR responded slightly stronger to the homologous LH than FSH, and the crocodylian FSHR was only stimulated by the homologous LH but not FSH. We therefore propose a modified paradigm with a neuroendocrine control of nonavian reptilian reproduction by a single GtHR and either 1 GtH in crocodylians or 2 GtHs in chelonians and squamate reptiles. Finally, we discuss hypotheses of tightly regulated temporal and spatial expression of the remaining FSHR in different gonadal somatic cells and temperature-dependent functions of the single nonavian reptilian GtHR.

Failure of oviposition in reptiles is either based on a pre- or postovulatory condition. Although postovulatory dystocia is easier to diagnose and treat, and undoubtedly pathological, the pathophysiology of failure of ovulation is poorly understood. The common perception is that of a static condition, a “follicular stasis,” and ovariectomy is the commonly recommended treatment. Unovulated follicles undergo a resorptive process. It is important to distinguish between follicular atresia (FA) and follicular regression (FR). FA is the selecting force on individual follicles during follicular development, a common and physiological process in all vertebrate species for limiting clutch and litter size. FR is the process of “follicular stasis,” the elimination of entire batches of late mature follicles in nonmammalian species. The etiology of FR is likely multifactorial, but there is evidence for a physiological, adaptive process to environmental or social conditions, observed not only in captivity but also in natural habitats. Although the complete resorption may take several months and some forms (in particular, cystic atresia) may be mistaken for a pathological condition, FR is neither a static nor a pathological process per se. It is, however, undisputed that some affected reptiles suffer from the consequences of accumulated unovulated follicles, including yolk coelomitis, metabolic derangements, and mechanical impacts of the coelomic mass effect. In addition, the endocrinological impact of corpora atretica (whitening bodies) on the ovulation of future batches of follicles and the welfare of affected animals remain unknown. Although ovariectomy may in fact be the best option for a companion pet reptile, premature interventions and loss of reproductive potential are detrimental for the sustainability of conservation breeding programs. Acknowledging the continuous resorptive and physiological nature of FR, monitoring and allowing enough time for follicular resorption, and performing partial ovariectomy are recommended for female reptiles in breeding situations.

Two influential concepts in tissue patterning are Wolpert’s positional information and Turing’s self-organized reaction–diffusion (RD). The latter establishes the patterning of hair and feathers. Here, our morphological, genetic, and functional—by CRISPR-Cas9–mediated gene disruption—characterization of wild-type versus “scaleless” snakes reveals that the near-perfect hexagonal pattern of snake scales is established through interactions between RD in the skin and somitic positional information. First, we show that ventral scale development is guided by hypaxial somites and, second, that ventral scales and epaxial somites guide the sequential RD patterning of the dorsolateral scales. The RD intrinsic length scale evolved to match somite periodicity, ensuring the alignment of ribs and scales, both of which play a critical role in snake locomotion.

Aldabra giant tortoises (Aldabrachelys gigantea) are currently listed as Vulnerable on the IUCN Red List of Threatened Species. However, negative impacts of sea-level rise are predicted to result in an overall population decline of 40-65 % over the next 100 years, rendering the species Endangered. Captive propagation is an important tool for in- and ex-situ species conservation, but breeding success outside the tortoises’ native island habitats has been very limited. Until now, the reproductive cycle of Aldabra tortoises has only been described in anatomic and behavioural studies. During a one-year period, plasma of four female and four male wild tortoises on Aldabra Atoll were examined monthly for levels of gonadal steroid hormones (oestradiol, testosterone, progesterone). Plasma oestradiol and testosterone values as well as meteorological data of the sampling period corresponded to previously published reports on seasonal changes in anatomy, behaviour and climate on the Aldabra Atoll. Seasonal changes in plasma testosterone were evident in males, with high values from January through April, reflecting previously described testicular growth and breeding season, followed by a nadir in August and September. In females, plasma oestradiol levels displayed seasonal changes, coinciding with reported ovarian growth from January to May. The obtained data provide prerequisite knowledge for endocrinological monitoring of reproductive processes and management of breeding programs, both ex-situ as in-situ, to establish reserve- and rewilded populations.

Despite the growing knowledge and literature on primate medicine, assessment and treatment of behavioral abnormalities in nonhuman primates (NHPs) is an underdeveloped field. There is ample evidence for similarity between humans and great apes, including basic neurologic physiology and emotional processes, and no substantial argument exists against a concept of continuity for abnormal conditions in NHPs that emerge in response to adverse experiences, akin to human psychopathology. NHPs have served as models for human psychopathologies for many decades, but the acquired knowledge has only hesitantly been applied to primates themselves. This review aims to raise awareness among the veterinary community of the wealth of literature on NHP psychopathologies in human medicine and anthropology literature and calls for the necessity to include mental health assessments and professionally structured treatment approaches in NHP medicine. Growing understanding about causes and pathogenesis of abnormal beh...

In 2015, we identified an avian hepatitis B virus associated with hepatitis in a group of captive elegant-crested tinamous (Eudromia elegans) in Germany. The virus’ full-length genome shares <76% sequence identity with other avihepadnaviruses. The virus may therefore be considered a new extant avian hepadnavirus.

In order to develop a long-term anesthesia for flighty antelope species in field situations, two different protocols for induction and maintenance with an intravenous infusion were evaluated in wild-caught impala (Aepyceros melampus). Ten adult female impala were induced with two induction protocols: one consisted of 0.2 mg/kg medetomidine, 4 mg/kg ketamine, and 0.15 mg/kg butorphanol (MKB) and one consisted of 0.375 mg/kg etorphine, 0.2 mg/kg medetomidine, and 0.2 mg/kg midazolam (EMM). In both treatments, anesthesia was maintained with a continuous intravenous infusion (CII) at an initial dose rate of 1.2 μg/kg per hr medetomidine, 2.4 mg/kg per hr ketaminen and 36 μg/kg per hr midazolam. Partial reversal was achieved with naltrexone (2 : 1 mg butorphanol; 20 : 1 mg etorphine) and atipamezole (5 : 1 mg medetomidine). Evaluation of anesthesia included respiratory rate, heart rate, rectal temperature, arterial blood pressure, oxygen saturation, end tidal carbon dioxide tension, and tidal volume a...