Latitudinal Variation in Seasonal Activity and Mortality in Ratsnakes (Elaphe obsoleta)

The ecology of ectotherms should be particularly affected by latitude because so much of their biology is temperature dependent. Current latitudinal patterns should also be informative about how ectotherms will have to modify their behavior in response to climate change. We used data from a total of 175 adult black ratsnakes (Elaphe obsoleta) radio tracked in Ontario, Illinois, and Texas, a latitudinal distance of \u3e 1500 km, to test predictions about how seasonal patterns of activity and mortality should vary with latitude. Despite pronounced differences in temperatures among study locations, and despite ratsnakes in Texas not hibernating and switching from diurnal to nocturnal activity in the summer, seasonal patterns of snake activity were remarkably similar during the months that snakes in all populations were active. Rather than being a function of temperature, activity may be driven by the timing of reproduction, which appears similar among populations. Contrary to the prediction that mortality should be highest in the most active population, overall mortality did not follow a clinal pattern. Winter mortality did increase with latitude, however, consistent with temperature limiting the northern distribution of ratsnakes. This result was opposite that found in the only previous study of latitudinal variation in winter mortality in reptiles, which may be a consequence of whether or not the animals exhibit true hibernation. Collectively, these results suggest that, at least in the northern part of their range, ratsnakes should be able to adjust easily to, and may benefit from, a warmer climate, although climate-based changes to the snakes\u27 prey or habitat, for example, could alter that prediction

USE OF INHALANT ANESTHETICS IN THREE SNAKE SPECIES

Different snake species respond differently to various anesthetic agents. Hence, an anesthetic procedure developed for one species cannot necessarily be safely transferred to another species. The goal of this paper is to summarize our experience using inhalant anesthetics on three snake species, including both procedures that were successful and those we found to be less satisfactory. We found isoflurane delivered with a precision vaporizer to be the best agent to anesthetize black rat snakes (Elaphe o. obsoleta). Sex and mass did not seem to affect induction times in black rat snakes, but larger female rat snakes recovered faster from anesthesia than smaller females. Halothane delivered in the open method provided consistent anesthesia in northern water snakes (Nerodia s. sipedon), although it caused some mortality and should not be used on debilitated patients. Halothane delivered with a precision vaporizer may be used to anesthetize eastern massasauga rattlesnakes (Sistrurus c. catenatus). However, care must be taken to prevent mortality resulting from anesthetic overdose. Sex and mass had no effect on induction and recovery times in the rattlesnakes, but stressed animals require longer induction and recovery times

libcov: A C++ bioinformatic library to manipulate protein structures, sequence alignments and phylogeny

BACKGROUND: An increasing number of bioinformatics methods are considering the phylogenetic relationships between biological sequences. Implementing new methodologies using the maximum likelihood phylogenetic framework can be a time consuming task. RESULTS: The bioinformatics library libcov is a collection of C++ classes that provides a high and low-level interface to maximum likelihood phylogenetics, sequence analysis and a data structure for structural biological methods. libcov can be used to compute likelihoods, search tree topologies, estimate site rates, cluster sequences, manipulate tree structures and compare phylogenies for a broad selection of applications. CONCLUSION: Using this library, it is possible to rapidly prototype applications that use the sophistication of phylogenetic likelihoods without getting involved in a major software engineering project. libcov is thus a potentially valuable building block to develop in-house methodologies in the field of protein phylogenetics

The Q Branch Cooling Anomaly Can Be Explained by Mergers of White Dwarfs and Subgiant Stars

Gaia's exquisite parallax measurements allowed for the discovery and characterization of the Q branch in the Hertzsprung-Russell diagram, where massive C/O white dwarfs (WDs) pause their dimming due to energy released during crystallization. Interestingly, the fraction of old stars on the Q branch is significantly higher than in the population of WDs that will become Q branch stars or that were Q branch stars in the past. From this, Cheng et al. inferred that ~6% of WDs passing through the Q branch experience a much longer cooling delay than that of standard crystallizing WDs. Previous attempts to explain this cooling anomaly have invoked mechanisms involving super-solar initial metallicities. In this paper, we describe a novel scenario in which a standard composition WD merges with a subgiant star. The evolution of the resulting merger remnant leads to the creation of a large amount of 26Mg, which, along with the existing 22Ne, undergoes a distillation process that can release enough energy to explain the Q branch cooling problem without the need for atypical initial abundances. The anomalously high number of old stars on the Q branch may thus be evidence that mass transfer from subgiants to WDs leads to unstable mergers.Comment: Accepted for publication in ApJL. Added text and a figure to better motivate the initial conditions of the merger remnant evolution. Also amended text regarding the estimated numbers of WD + subgiant merger

Reduced mammary gland carcinogenesis in transgenic mice expressing a growth hormone antagonist

Several reports have provided evidence that body size early in life is positively correlated with risk of subsequent breast cancer, but the biological basis for this relationship is unclear. We examined tumour incidence in transgenic mice expressing a growth hormone (GH) antagonist and in non-transgenic littermates following exposure to dimethylbenz[a]anthracene (DMBA), a well characterized murine mammary gland carcinogen. The transgenic animals had lower IGF-I levels, were smaller in terms of body size and weight, and exhibited decreased tumour incidence relative to controls. The demonstration that both body size early in life and breast cancer incidence are influenced by experimental perturbation of the GH–IGF-I axis in a transgenic model provides evidence that variability between individuals with respect to these hormones underlies the relationship between body size early in life and breast cancer risk observed in epidemiological studies. © 2001 Cancer Research Campaign http://www.bjcancer.co

Human hypocretin and melanin-concentrating hormone levels are linked to emotion and social interaction.

The neurochemical changes underlying human emotions and social behaviour are largely unknown. Here we report on the changes in the levels of two hypothalamic neuropeptides, hypocretin-1 and melanin-concentrating hormone, measured in the human amygdala. We show that hypocretin-1 levels are maximal during positive emotion, social interaction and anger, behaviours that induce cataplexy in human narcoleptics. In contrast, melanin-concentrating hormone levels are minimal during social interaction, but are increased after eating. Both peptides are at minimal levels during periods of postoperative pain despite high levels of arousal. Melanin-concentrating hormone levels increase at sleep onset, consistent with a role in sleep induction, whereas hypocretin-1 levels increase at wake onset, consistent with a role in wake induction. Levels of these two peptides in humans are not simply linked to arousal, but rather to specific emotions and state transitions. Other arousal systems may be similarly emotionally specialized

Balance task and head orientation dependency of vestibular reflexes in neck muscles

Human upright posture of both the head and body is facilitated by the CNS’s ability to integrate multiple sensory feedback signals, as well as its discernibility of the motor commands that maintain this stabilization. The vestibular organ in particular detects motion of the head-in-space, which is transformed according to on-going head and body orientation into appropriate motor responses. However, when motor commands do not contribute to the control of standing posture, and are incongruent with their expected sensory consequences, vestibulomuscular responses in the lower limb undergo unconscious suppression. In this study, we investigated whether vestibular response suppression occurs in neck muscles under conditions where the muscles are active but not engaged in a task to balance the head. In addition, we examined the effects of head orientation to identify spatial transformation of vestibular reflex responses. Eight subjects were exposed to stochastic vestibular stimulation (0-75 Hz) in a seated condition while their head was either free or fixed, and rotated at either 0 or 60°. In head-free conditions, subjects were asked to rotate their head 60° to the left in order to activate agonist neck muscle pairs (sternocleidomastoid - SCM and splenius capitis - SPL). In head-fixed conditions, subjects performed isometric neck muscle contractions in yaw at orientations of 0° and 60°, as well as flexion, extension and co-contraction at an orientation of 0°. Intramuscular EMG was collected bilaterally in SCM and SPL muscles. Muscle responses correlated to the input stimuli were significant (P < 0.05) for all conditions provided the muscle was used in contraction. Neither muscle underwent the expected vestibulomuscular suppression when not engaged in the balance task (i.e. head-fixed). Nevertheless, the magnitude of the SPL responses decreased by 22% when the head was fixed whereas SCM responses were unaffected. The effect of head fixation only in SPL suggests differences in neural pathways across muscles, possibly via alternative pathways known to exist in the SPL from the well-established monosynaptic vestibulospinal inputs in SCM and SPL. For both muscles, the effect of orientation and force direction had no effect on muscles responses. Since the stimulation is fixed relative to the head, the same muscles are activated to respond to the input stimulus at both orientations and all force directions. These results indicate that the vestibular pathways connecting neck muscles are less susceptible to suppression than lower limb muscles, most likely because the monosynaptic inputs innervating them are subject to less central control