Chronic wounds are a major health problem that cause millions of dollars in expenses every year. Among all the treatments used, active wound treatments such as enzymatic treatments represent a cheaper and specific option with a fast growth category in the market. In particular, bacterial and plant proteases have been employed due to their homology to human proteases, which drive the normal wound healing process. However, the use of these proteases has demonstrated results with low reproducibility. Therefore, alternative sources of proteases such as snake venom have been proposed. Here, we performed a functional mining of proteases from rattlesnakes (Crotalus ornatus, C. molossus nigrescens, C. scutulatus, and C. atrox) due to their high protease predominance and similarity to native proteases. To characterize Crotalus spp. Proteases, we performed different protease assays to measure and confirm the presence of metalloproteases and serine proteases, such as the universal protease assay and zymography, using several substrates such as gelatin, casein, hemoglobin, L-TAME, fibrinogen, and fibrin. We found that all our venom extracts degraded casein, gelatin, L-TAME, fibrinogen, and fibrin, but not hemoglobin. Crotalus ornatus and C. m. nigrescens extracts were the most proteolytic venoms among the samples. Particularly, C. ornatus predominantly possessed low molecular weight proteases (P-I metalloproteases). Our results demonstrated the presence of metalloproteases capable of degrading gelatin (a collagen derivative) and fibrin clots, whereas serine proteases were capable of degrading fibrinogen-generating fibrin clots, mimicking thrombin activity. Moreover, we demonstrated that Crotalus spp. are a valuable source of proteases that can aid chronic wound-healing treatments.

BackgroundGlobally, snake envenomation is a well-known cause of death and morbidity. In many cases of snakebite, myonecrosis, dermonecrosis, hemorrhage and neurotoxicity are present. Some of these symptoms may be provoked by the envenomation itself, but others are secondary effects of the produced oxidative stress that enhances the damage produced by the venom toxins. The only oxidative stress effect known in blood is the change in oxidation number of Fe (from ferrous to ferric) in hemoglobin, generating methemoglobin but not in other macromolecules. Currently, the effects of the overproduction of methemoglobin derived from snake venom are not extensively recorded. Therefore, the present study aims to describe the oxidative stress induced by Crotalus molossus nigrescens venom using erythrocytes.MethodsHuman erythrocytes were washed and incubated with different Crotalus molossus nigrescens venom concentrations (0–640 μg/mL). After 24 h, the hemolytic activity was measured followed by attenuated total reflectance-Fourier transform infrared spectroscopy, non-denaturing PAGE, conjugated diene and thiobarbituric acid reactive substances determination.ResultsLow concentrations of venom (<10 μg/mL) generates oxyhemoglobin release by hemolysis, whereas higher concentrations produced a hemoglobin shift of valence, producing methemoglobin (>40 μg/mL). This substance is not degraded by proteases present in the venom. By infrared spectroscopy, starting in 80 μg/mL, we observed changes in bands that are associated with protein damage (1660 and 1540 cm−1) and lipid peroxidation (2960, 2920 and 1740 cm−1). Lipid peroxidation was confirmed by conjugated diene and thiobarbituric acid reactive substance determination, in which differences were observed between the control and erythrocytes treated with venom.Conclusions Crotalus molossus nigrescens venom provokes hemolysis and oxidative stress, which induces methemoglobin formation, loss of protein structure and lipid peroxidation.

Variación estacional del contenido proteico y actividad de la PLA 2 del veneno de Crotalus molossus molossus entre especímenes de origen silvestre y en cautiverio Seasonal variation in protein content and PLA 2 activity of Crotalus molossus molossus venom from captive and wild specimens Palabras clave: Veneno; serpiente; Crotalus molossus molossus.

The desert pocket gopher (Geomys arenarius) is a fossorial herbivorous rodent of the family Geomyidae.  Its distribution range is restricted to New Mexico and Texas, in the United States of America, and northern Chihuahua, in México.  The Médanos de Samalayuca Flora and Fauna Protection Area (MSFFPA) is located in northern Chihuahua.  Different economic activities are carried out in this region, mainly irrigated crops of pecans (Carya illinoinensis).  Populations of G. arenarius have been recorded within these areas.  Therefore, the objective of this work was to define the extent of the trophic niche and the changes in the physical condition of G. arenarius in a ranch within the MSFFPA over three contrasting seasons (dry, wet, and post-wet).  Forty G. arenarius specimens were collected from Arantxa Ranch.  Morphometric measurements and the weight of collected individuals were recorded, and the digestive tract was removed to prepare histological slides.  Seven 25 m²-quadrants were established, and the species of the vegetation cover were recorded and collected for reference.  The Seasonal Fitness Index (IK) and Levin’s Niche Breadth Index were calculated.  Males had higher average measurements and weight than females.  The IK was 2.82 ± 0.47 in males and 2.64 ± 0.61 in females. Significant differences in the IK between seasons were only found in females.  The correlation between IK and plant cover was strong for males and females.  The diet mainly comprised Physalis hederifolia, Dimorphocarpa wislizeni, and Cenchrus incertus.  Levin’s index showed that G. arenarius is a specialist rodent.  Sexual dimorphism was evident, with males larger than females.  The physical condition index of gophers is influenced by resource availability. In other studies, this parameter has been related to changes in food availability.  It has been reported that gophers tend to feed mainly on crops; however, pecan cultivation was not a major element in the diet of the desert pocket gopher, as it feeds on the vegetation associated with crops.  Gophers are considered generalists; nonetheless, the present study showed that G. arenarius is a specialist, although this may be a consequence of anthropogenic activities.

Environmental temperatures often regulate the activity and physiological processes of ectotherms. Because environmental temperatures can vary significantly among seasons, lizards exposed to different thermal conditions in different months could differ in how they thermoregulate or behave. Here, we present a combination of field, laboratory, and modeling approaches to examine thermoregulation, habitat thermal quality, and hours of thermal restriction on activity in a saxicolous population of Urosaurus ornatus in two thermally contrasting months (June and October) in a micro-insular mountain system in the northern Chihuahuan Desert in Mexico. Both active and preferred body temperatures did not vary between months. In this population, U. ornatus is an active thermoregulator with highly accurate and efficient thermoregulation despite the thermal quality in both months. However, during the breeding season (June) activity is restricted (i.e., high number of hours of restriction) compared to the non-breeding season (October). Therefore, our results suggest that this saxicolous population of U. ornatus could be threatened by global climate change and it is essential to determine a conservation strategy for this population.