A draft genome sequence of the common, or spectacled caiman Caiman crocodilus

The common, or spectacled, caiman Caiman crocodilus is an abundant, widely distributed Neotropical crocodilian exhibiting notable morphological and molecular diversification. The species also accounts by far for the largest share of crocodilian hides on the global market, with the C. crocodilus hide trade alone valued at about US$86.5 million per year. We obtained 239,911,946 paired-end reads comprising approximately 72 G bases using IlluminaTM sequencing of tissue sampled from a single Caiman crocodilus individual. These reads were de-novo assembled and progressively aligned against the genomes of increasingly related crocodilians; liftoff was used to annotate the draft C. crocodilus genome assembly based on an Alligator mississipiensis (a confamilial species) annotation. The draft assembly has been submitted to the National Center for Biotechnology Information and both assembly and annotation are currently available for review at doi.org/10.5281/zenodo.4755063

Ventricular Septation and Outflow Tract Development in Crocodilians Result in Two Aortas With Bicuspid Semilunar Valves

The outflow tract of crocodilians resembles that of birds and mammals as ventricular septation is complete. The arterial anatomy however, presents with a pulmonary trunk originating from the right ventricular cavum, and two aortae originating from either the right or left ventricular cavum. Mixing of blood in crocodilians cannot occur at ventricular level as in other reptiles, but instead takes place at aortic root level by a shunt, the Foramen of Panizza, the opening of which is guarded by two facing semilunar leaflets of both bicuspid aortic valves. Methods. Developmental stages of Alligator mississipiensis, Crocodilus niloticus and Caiman latirostris, have been studied. Results and Conclusions. The outflow tract septation complex can be divided into 2 components. The aorto-pulmonary septum divides the pulmonary trunk from both aortae, whereas the interaortic septum divides the systemic from the visceral aorta. Neural crest cells are most likely involved in the formation of both components. Remodeling of the endocardial cushions and both septa results in the formation of bicuspid valves in all three arterial trunks. The foramen of Panizza originates intracardially as a channel in the septal endocardial cushion.

Short-term capture stress and its effects on corticosterone levels and heat shock proteins in captive American alligators (Alligator mississippiensis)

Heat shock proteins (HSPs) are important mediators of the normal cellular function and the cellular stress response. As such, HSPs are often utilized to measure the effects of stressors on organisms in vivo. However, multiple variables can influence their expression, including time or season, confounding results. To investigate the utility of HSPs in measuring effects of stressors in a top trophic carnivore, we captured 20 American alligators, Alligator mississipiensis (Daudin, 1802), placed them in burlap sacks for 2 hours and collected blood samples over four time points (baseline, 1 and 2 hours after placement into burlap sacks, and 24 hours after initial capture) to measure plasma corticosterone (the main crocodilian glucocorticoid) and levels of HSP60, HSP70, and HSP90. Time point significantly affected plasma corticosterone levels in alligators (p < 0.0001), with levels significantly elevated at 1, 2, and 24 hours, relative to baseline (all p < 0.05). However, capture stress did not affect HSP60, HSP70, or HSP90 in red blood cells (all p > 0.05). Our results suggest HSPs may be important biomarkers for investigating the impacts of stressors on captive and wild crocodilians, since they are not acutely elevated by capture or handling stress.

Living with Alligators: A Florida Reality

Living in Florida, we have to share our space with a very large reptile, the American alligator (Alligator mississipiensis). Because of Florida's booming population growth, people and alligators are constantly forced to cross paths, increasing the chances of conflict. Knowing where alligators live, how they behave, and what you can do to avoid conflict with alligators is key to sharing space safely (Figure 1). This document is WEC 203, one of a series of the Department of Wildlife Ecology and Conservation, UF/IFAS Extension. Original publication date September 2005. WEC203/UW230: Living with Alligators: A Florida Reality (ufl.edu)

Anestesia em Jacaré-americano (Alligator mississipiensis) para Amputação de Membro

Background: The knowledge of secure anesthetic protocols for reptiles is very important, especially because they are aggressive species and they have peculiar physiology, unpredictable reactions to the same drug in different environmental conditions and different physiological responses can be observed. The anesthetic protocol aims immobilization, analgesia and muscle relaxation for adequate, safe and easily reversible anesthesia. Few reports have been described on anesthesia in animals and, before that, the objective of this study is to report the anesthetic protocol that was used and vital parameters monitoring in an Alligator mississipiensis that was submitted to surgery for limb amputation.Case: A female American alligator was attended, with about 8-year-old, 2 m long and 268,964 pounds, with fight history with other animal six months ago, resulting in a wound in the right toracic limb. When the lesion occurred, it was the breeding season of the species, so we chose not to perform the treatment at that time. An X-ray of the member was performed, which showed, among other changes, osteomyelitis and septic arthritis. Thus, the limb amputation was indicated. Ketamine association (10 mg/kg) and medetomidine (0.1 mg/kg) were used as anestesic premedication, both administered intramuscularly. For anesthetic induction, propofol (4 mg/kg) intravenously was used. The animal was intubated using an endotracheal tube number 11 without inflating the cuffing, and for the maintenance it was employed isoflurane. The heart rate was measured using Doppler and the respiratory rate by visual and balloon observation in the oxygen circular system. The other parameters were measured using a multiparameter monitor sensor connected to the tongue. The local anesthetic block was made close to the incision line, the medium third humerus with 2 mg/kg of 2% lidocaine without vasoconstrictor, diluted in 0.9% NaCl until the volume of 10 mL is completed to assist in analgesia. The parameters recorded during the procedure, which lasted 80 min, remained within the normal pattern of species (three breaths per minute, 30 heart beats per min and 80.6°F temperature). After surgery meloxicam (0.2 mg/kg) and atipamezole reverser (0.5 mg/kg) were administered, both intramuscularly. The animal took about seven hours to fully return from anesthesia.Discussion: Different anesthetics protocols may be employed to crocodilians using both local anesthetic techniques and general, in order to promote analgesia, muscle relaxation and adequate anesthesia. Still, it is very important to monitor the patient during the procedure, in order to be a different physiology kind of species. Cardiac auscultation is quite difficult in these animals, so it is recommended to use non-invasive electronic equipment as the Doppler, the multiparameter monitor, the pulse oximeter and esophageal stethoscope for assistance in monitoring heart and respiratory rate, providing important trans-operative information. The realization of amputations in crocodilians is common, however there are few reports in the literature about their anesthesia, this way, this article has a significant contribution to a better anesthetic protocol clarification to be used in these animals. Therefore, it is concluded that the anesthetic protocol based on premedication with ketamine and medetomindina, propofol induction and maintenance with isoflurane, besides local anesthesia with lidocaine was effective and safe for thoracic limb amputation surgery in an American alligator.

Quantitative RT-PCR analyses of five evolutionary conserved genes in Alligator brains during development

Gene expression was investigated in the major brain subdivisions (telencephalon, diencephalon, midbrain and hindbrain) in a representative reptile, Alligator mississipiensis, during the later stages of embryonic development. The following genes were examined: voltage-gated sodium channel isoforms: NaV1.1 and NaV1.2; synaptic vesicle 2a (SV2a); synaptophysin; and calbindin 2. With the exception of synaptophysin, which was only expressed in the telencephalon, all genes were expressed in all brain regions sampled at the time periods examined. For NaV1.1, gene expression varied according to brain area sampled. When compared with NaV1.1, the pattern of NaV1.2 gene expression differed appreciably. The gene expression of SV2a was the most robust of any of the genes examined. Of the other genes examined, although differences were noted, no statistically significant changes were found either between brain part or time interval. Although limited, the present analysis is the first quantitative mRNA gene expression study in any reptile during development. Together with future experiments of a similar nature, the present gene expression results should determine which genes are expressed in major brain areas at which times during development in Alligator. When compared with other amniotes, these results will prove useful for determining how gene expression during development influences adult brain structure.