Cold Anesthesia Research Articles

Effect of brief exposures of anesthesia on thermotolerance and metabolic rate of the spotted-wing fly, Drosophila suzukii: Differences between sexes?

The spotted-wing fly, Drosophila suzukii, is a world-wide pest insect for which there is increasing interest in its physiological traits including metabolism and thermotolerance. Most studies focus only on survival to different time exposures to extreme temperatures, mainly in female flies. In addition, it has not been tested yet how anesthesia affects these measurements. We analyzed the effects of anesthesia by brief exposures to cold, anoxia by CO2 or N2 on three standard thermotolerance assays, as well as the aerobic metabolic rate in both sexes. For heat tolerance we measured CTmax by thermolimit respirometry, and CTmin and chill-coma recovery time for cold tolerance. Aerobic metabolism was calculated by CO2 production of individual flies in real time by open flow respirometry. Results showed that females have a significantly higher V̇CO2 for inactive (at 25 °C) and maximum metabolic rate than males. This difference is mainly explained by body mass and disappears after mass correction. Males had a more sensitive MR to temperature than females showed by a significantly higher Q10 (2.19 vs. 1.98, for males and females, respectively). We observed a significantly lower CTmin (X2 = 4.27, P = 0.03) in females (3.68 ± 0.38 °C) than males (4.56 ± 0.39 °C), although we did not find significant effects of anesthesia. In contrast, anesthesia significantly modifies CTmax for both sexes (F3,62 = 7.86, P < 0.001) with a decrease of the CTmax in cold-anesthetized flies. Finally, we found a significantly higher CTmax in females (37.87 ± 0.07 °C) than males (37.36 ± 0.09 °C). We conclude that cold anesthesia seems to have detrimental effects on heat tolerance, and females have broader thermotolerance range than males, which could help them to establish in invaded temperate regions with more variable environmental temperatures.

Erratum: Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs.

Erratum: Eyestalk Ablation to Increase Ovarian Maturation in Mud Crabs.

Cold Shock Disrupts Massed Training-Elicited Memory in Drosophila.

Memory consolidation is a time-dependent process occurring over hours, days, or longer in different species and requires protein synthesis. An apparent exception is a memory type in Drosophila elicited by a single olfactory conditioning episode, which ostensibly consolidates quickly, rendering it resistant to disruption by cold anesthesia a few hours post-training. This anesthesia-resistant memory (ARM), is independent of protein synthesis. Protein synthesis independent memory can also be elicited in Drosophila by multiple massed cycles of olfactory conditioning, and this led to the prevailing notion that both of these operationally distinct training regimes yield ARM. Significantly, we show that, unlike bona fide ARM, massed conditioning-elicited memory remains sensitive to the amnestic treatment two hours post-training and hence it is not ARM. Therefore, there are two protein synthesis-independent memory types in Drosophila.

TRPA1s act as chemosensors but not as cold sensors or mechanosensors to trigger the swallowing reflex in rats

We examined the role of TRPA1s in triggering the swallowing reflex. TRPA1s predominantly localized on thin nerve fibers and fibroblast-like cells in swallowing-related regions and on small to medium-sized superior laryngeal nerve-afferents in the nodose–petrosal–jugular ganglionic complex. Topical application of a TRPA1 agonist, allyl isothiocyanate (AITC), dose-dependently triggered swallowing reflexes. Prior topical application of a TRPA1 antagonist significantly attenuated the AITC-induced reflexes. Application of cold AITC (4 °C) very briefly reduced the on-site temperature to < 17 °C (temperature at which TRPA1s can be activated), but had no effect on triggering of the reflex. By contrast, reducing the on-site temperature to < 17 °C for a longer time by continuous flow of cold AITC or by application of iced AITC paradoxically delayed/prevented the triggering of AITC-induced reflexes. Prior application of the TRPA1 antagonist had no effect on the threshold for the punctate mechanical stimuli-induced reflex or the number of low-force or high-force continuous mechanical pressure stimuli-induced reflexes. TRPA1s are functional and act as chemosensors, but not as cold sensors or mechanosensors, for triggering of the swallowing reflex. A brief cold stimulus has no effect on triggering of the reflex. However, a longer cold stimulus delays/prevents triggering of the reflex because of cold anesthesia.

A double-blinded randomized clinical trial for pain perception: The efficacy and safety of topical cold saline solution anesthesia in phacoemulsification.

Purpose:To compare the efficacy and safety of cold saline solution (0.9% NaCl) with topical ophthalmic proparacaine for maintaining topical anesthesia of patients undergoing phacoemulsification surgery.Methods:The prospective, double-blinded, and randomized clinical study was randomly assigned to two groups that underwent phacoemulsification surgery due to cataracts. The cold saline group included 86 eyes of 86 patients with topical anesthesia of cold saline solution alone. The proparacaine group included 84 eyes of 84 patients with topical ophthalmic proparacaine (room temperature) anesthesia alone. The patients were scored according to a pain survey questionnaire of Visual Analog Scale (VAS) ranked between 0 and 10. The surgeon scored surgical experience by a Surgeon Questionnaire Scale (SQS) in three parameters, each of which was ranked from 1 to 3 based on questions regarding ease and comfort during the surgery.Results:The mean VAS scores were 1.29 ± 0.65 and 1.22 ± 0.66 for the cold saline and proparacaine groups, respectively (P = 0.182). The mean scores of SQS (lower values represented favorable results) were 4.11 ± 0.76 and 3.97 ± 0.74 in the cold saline and proparacaine groups, respectively (P = 0.163). Ten patients in the proparacaine group experienced corneal epitheliopathy in the postoperative period.Conclusion:As an easily accessible and cost-effective method, cold saline solution alone might be an alternative to topical ophthalmic proparacaine alone with comparable safe and effective results. The absence of allergic or toxic effects also provided a significant advantage in the cold saline application.

James Darsie Morrison and Cold Anesthesia: A Technique of Antiquity and Modernity

James Darsie Morrison and Cold Anesthesia: A Technique of Antiquity and Modernity

Tumescence Anesthesia Solution–Assisted Laser Ablation Treatment of Lower Limb Varicose Veins: The Effect of Temperature of the Tumescence Anesthesia Solution on Intraoperative and Postoperative Pain, Clinical Observations, and Comprehensive Nursing Care

To investigate the effect of cold and room temperature tumescence anesthesia solution (TAS) on the treatment of lower limb varicose veins via endovenous laser ablation. On the basis of the TAS temperature, patients were divided into two groups: group A (n = 26) received room temperature (24°C) TAS, and group B (n = 25) received cold (4°C) TAS. A numerical rating scale was used to evaluate pain. Perioperative and intraoperative nursing care and clinical observations were performed following a generalized standard. Percentages of patients who felt pain in groups A and B were 69.2% and 36.0%. Average numerical rating scale scores of patients in the two groups (A and B) on the day of surgery and on postoperative days 1, 2, and 3 were 4.3 versus 2.1, 3.5 versus 1.0, 3.0 versus 0.8, and 1.6 versus 0.3, respectively. Cold TAS reduces intraoperative and postoperative pain more effectively than room temperature.

Factors affecting sequential sex allocation in the parasitoid wasp Gryon japonicum

AbstractFemale wasps of the solitary egg parasitoid Gryon japonicum (Hymenoptera: Platygastridae) allocate male and female offspring in a particular sequence to successive hosts. Male eggs are typically laid in the second host, and the sex allocation sequence is reset after a certain period of time. The present study aimed to examine the underlying mechanism to hold information and reset the sequence by using eggs of Riptortus pedestris (Heteroptera: Alydidae) as hosts. After completion of initial oviposition, a female wasp was treated by cold anesthesia for 1 h, exposure to a parasitized host for 3 h, or being kept at 15°C in darkness for 24 h, and then presented with three host eggs. Cold‐anesthetized females did not reset the sex allocation sequence, indicating that cold anesthesia did not block the mechanism of holding information about oviposition order. Frequent encounters with parasitized hosts were also insufficient to reset the sequence. However, being kept in cool, dark conditions significantly affected resetting, suggesting that low temperature lengthened the time required to reset the sequence. This implies that it is probable that the mechanism to hold information and reset sex allocation sequence in G. japonicum involves metabolism.

Who is the boss? Individual recognition memory and social hierarchy formation in crayfish.

Under laboratory conditions, crayfish establish hierarchical orders through agonistic encounters whose outcome defines the dominant one and one, or more, submissive animals. These agonistic encounters are ritualistic, based on threats, pushes, attacks, grabs, and avoidance behaviors that include retreats and escape responses. Agonistic behavior in a triad of unfamiliar, size-matched animals is intense on the first day of social interaction and the intensity fades on daily repetitions. The dominant animal keeps its status for long periods, and the submissive ones seem to remember 'who the boss is'. It has been assumed that animals remember and recognize their hierarchical status by urine signals, but the putative substance mediating this recognition has not been reported. The aim of this work was to characterize this hierarchical recognition memory. Triads of unfamiliar crayfish (male animals, size and weight-matched) were faced during standardized agonistic protocols for five consecutive days to analyze memory acquisition dynamics (Experiment 1). In Experiment 2, dominant crayfish were shifted among triads to disclose whether hierarchy depended upon individual recognition memory or recognition of status. The maintenance of the hierarchical structure without behavioral reinforcement was assessed by immobilizing the dominant animal during eleven daily agonistic encounters, and considering any shift in the dominance order (Experiment 3). Standard amnesic treatments (anisomycin, scopolamine or cold-anesthesia) were given to all members of the triads immediately after the first interaction session to prevent individual recognition memory consolidation and evaluate its effect on the hierarchical order (Experiment 4). Acquisition of hierarchical recognition occurs at the first agonistic encounter and agonistic behavior gradually diminishes in the following days; animals keep their hierarchical order despite the inability of the dominant crayfish to attack the submissive ones. Finally, blocking of protein synthesis or muscarinic receptors and cold anesthesia impair memory consolidation. These findings suggest that agonistic encounters induces the acquisition of a robust and lasting social recognition memory in crayfish.

Testing the habituation assumption underlying models of parasitoid foraging behavior.

BackgroundHabituation, a form of non-associative learning, has several well-defined characteristics that apply to a wide range of physiological and behavioral responses in many organisms. In classic patch time allocation models, habituation is considered to be a major mechanistic component of parasitoid behavioral strategies. However, parasitoid behavioral responses to host cues have not previously been tested for the known, specific characteristics of habituation.MethodsIn the laboratory, we tested whether the foraging behavior of the egg parasitoid Trissolcus basalis shows specific characteristics of habituation in response to consecutive encounters with patches of host (Nezara viridula) chemical contact cues (footprints), in particular: (i) a training interval-dependent decline in response intensity, and (ii) a training interval-dependent recovery of the response.ResultsAs would be expected of a habituated response, wasps trained at higher frequencies decreased their behavioral response to host footprints more quickly and to a greater degree than those trained at low frequencies, and subsequently showed a more rapid, although partial, recovery of their behavioral response to host footprints. This putative habituation learning could not be blocked by cold anesthesia, ingestion of an ATPase inhibitor, or ingestion of a protein synthesis inhibitor.DiscussionOur study provides support for the assumption that diminishing responses of parasitoids to chemical indicators of host presence constitutes habituation as opposed to sensory fatigue, and provides a preliminary basis for exploring the underlying mechanisms.

Adenosine monophosphate-activated protein kinase from the mud crab, Scylla paramamosain: cDNA cloning and profiles under cold stress.

Adenosine monophosphate-activated protein kinase (AMPK), an important energy sensor, is crucial for organism survival under adverse conditions. In this study, the roles of this gene under cold stress in a warm-water mud crab, Scylla paramamosain was investigated. The full-length cDNA (SpAMPK) was 1884 bp and its open reading frame of 1566 bp was isolated and characterized. The expressions of SpAMPK detected by quantitative real-time PCR (qRT-PCR) in various tissues revealed that the highest expression was in the hepatopancreas. The profiles of SpAMPK gene in the hepatopancreas, chela muscle and gill were detected when the subadult crabs were exposed to the four temperature conditions of 10, 15, 20 and 25°C. The results showed that the expression patterns of SpAMPK mRNA in the three tissues were significantly higher when crabs were exposed to 15°C than the other three temperature treatments, while at 10°C treatment, the SpAMPK mRNA was lowest among the four temperature treatments. These findings suggested that the high expression of SpAMPK mRNA might initiate ATP-producing pathways to generate energy to cope with cold stress at 15°C treatment, which was slightly below the range of optimum temperatures; while treatment at 10°C, far lower than optima, the low expression of SpAMPK mRNA could reduce the energy expenditure and thus induce the crabs into cold anesthesia. The results of SpAMPK in this study might contribute to the understanding of the molecular mechanism of acclimation to cold hardiness in S. paramamosain.

Transfer of optogenetic vectors into the brain of neonatal animals to study neuron functions during subsequent periods of development

Optogenetics, that is, the control of cell activity using light-sensitive ion channels opsins with light of a specific wavelength, is increasingly being used to study activities and functions of neurons. Expression of opsins in the cell membrane, followed by the acquisition by the cell of the sensitivity to light is achieved by means of viral vectors, often created on the basis of lentiviral or adeno-associated (AAV) viruses bearing the nucleotide sequence encoding the photo-channel proteins. Inclusion of the cell-specific promoter of interest into the transgene-expression cassette allows opsin to be produced only in the target cells. The aim of this work was to briefly describe the optogenetic method, as well as to analyze the possibility to use administration of viral vectors into the brain of neonatal animals to study the function of neurons in vivo during subsequent periods of development. In this analysis, 3-day-old rat pups received intracerebroventricular injections of optovector (pAAV-CAMKIIa-ChR2h134-YFP), coding for a photo channel, which activates neurons, and the yellow fluorescent marker protein under the CAMKIIa promoter specific for glutamatergic neurons under cold anesthesia. The peak expression of the transferred gene is usually achieved at week 3–5 after the transfer of the vector, which is what was also observed in our experiments. Stimulation of the hippocampal neurons with blue light in the 20-day-old animals, to which opto-vector was transferred at the 3rd day of life, increased the discharge activity of these neurons. This light stimulation increased expression of the recognized marker of neuronal activation protein c-Fos in these photosensitive cells too. The same experiments with older animals, 60 days after the neonatal opto-channel gene transfer, revealed no noticeable expression of this channel or photoactivation of target neurons of the hippocampus. Thus, neonatal administration of a viral vector carrying an opto-channel gene is suitable for the study of brain neurons in rats of juvenile age, and requires additional control for gene expression during subsequent periods of development.

ТЕМПЕРАТУРНАЯ ЗАВИСИМОСТЬ ИЗМЕНЕНИЯ МАССЫ ТЕЛА И СОДЕРЖАНИЯ В НЕМ ВОДЫ У ПЧЕЛ (Apis mellifera L.) ПРИ АНЕСТЕЗИИ ДИОКСИДОМ УГЛЕРОДА

In bees Apis mellifera L., similar to other insects, the respiration depends directly on temperature, being suppressed as the temperature approaches the upper limit of viability. High hypoxia tolerance is known to be a characteristic feature of honey bees. In winter, bees are influenced by the high СО 2 level when the law temperatures stimulate their aggregation in a limited zone of the nest space. In adaptation of bees to a wide range of outer temperature, the effect of hypoand hyperthermia under hypoxia are still not studied. Because the high СО 2 concentrations act as anesthetics, we examined in dynamics a physiological effect of temperature (0 °С, 25 °С, and 35 °С), particularly body weight and water losses, when the systems regulating metabolism and respiration activity in insects are out of active use. The worker bees of spring and summer generations from the same families were investigated. СО 2 was shown to influence the body weight losses, due to the water losses mainly. If the temperature changes from the parameter registered inside a hive to that causing a cold numb, the weigh of and the water content in bees’ head, thorax and abdomen decreased slowly. Because of repressed respiration under cold numb and anesthesia, the transpiration occurs through an integument.

A high-throughput method of hemolymph extraction from adult Drosophila without anesthesia

A rapid and cost-effective method of sampling hemolymph from the model insect Drosophila melanogaster is needed for studies in several fields, including ionoregulatory physiology, metabolism, immunology and toxicology. Here, we describe the construction and use of a device that uses airflow and pressure to manipulate adult flies and extract high-volume hemolymph samples. This method is rapid and inexpensive, and does not require cold or CO2 anesthesia at any point in the sampling process, thus avoiding the possible confounding effects of these treatments on the biochemical properties of the hemolymph sampled. To demonstrate one use for this method, we measure active concentrations of Na+ and K+ in isolated hemolymph droplets from individual adult D. melanogaster using an ion-selective microelectrode technique.

Comparing cold and warm tumescent anesthesia for pain perception during and after the endovenous laser ablation procedure with 1470 nm diode laser

The aim of this study was to compare the pain perception and side effects during and after endovenous laser ablation with a 1470 nm diode laser using cold or room temperature tumescence anesthesia. One hundred and one patients were randomly assigned in two groups. Group A received room temperature (+24℃) and Group B received cold (+4℃) tumescence fluid, which was used for local anesthesia in the track of great saphenous vein. A visual analog score was recorded immediately after the procedure. Patients were asked to register pain scores and the amount of pain medication consumed during the week. There was no significant difference concerning gender, age, Clinical Etiological Anatomical Pathological Classification, body mass index, or diameter of the treated vein. In Group A, the mean linear endovenous energy density was 59.5 J/cm and in Group B, it was 60.4 J/cm. The average visual analog score after the endovenous laser ablation procedure in Group A was 5 and in Group B was 2. Third day after the procedure, the average visual analog score in Group A was 3 and in Group B was 1. Patients in Group B needed significantly less analgesics compared with patients in Group A (p<0.05). The most frequent side effects in both groups were ecchymosis, induration, and minor paraesthesia, all of which were more common in Group A (p < 0.001). To date, most published endovenous laser ablation series describe the use of room temperature tumescence fluid infiltration of the perivenous stroma for tumescent analgesia and protection against thermal injury to the nearby structures. We describe an alternative technique using cold tumescence fluid infiltration, which is equally effective as, but safer than, room temperature tumescence fluid infiltration, and which yields better visual analog scores.

FlyNap (Triethylamine) Increases the Heart Rate of Mosquitoes and Eliminates the Cardioacceleratory Effect of the Neuropeptide CCAP

FlyNap (triethylamine) is commonly used to anesthetize Drosophila melanogaster fruit flies. The purpose of this study was to determine whether triethylamine is a suitable anesthetic agent for research into circulatory physiology and immune competence in the mosquito, Anopheles gambiae (Diptera: Culicidae). Recovery experiments showed that mosquitoes awaken from traditional cold anesthesia in less than 7 minutes, but that recovery from FlyNap anesthesia does not begin for several hours. Relative to cold anesthesia, moderate exposures to FlyNap induce an increase in the heart rate, a decrease in the percentage of the time the heart contracts in the anterograde direction, and a decrease in the frequency of heartbeat directional reversals. Experiments employing various combinations of cold and FlyNap anesthesia then showed that cold exposure does not affect basal heart physiology, and that the differences seen between the cold and the FlyNap groups are due to a FlyNap-induced alteration of heart physiology. Furthermore, exposure to FlyNap eliminated the cardioacceleratory effect of crustacean cardioactive peptide (CCAP), and reduced a mosquito’s ability to survive a bacterial infection. Together, these data show that FlyNap is not a suitable substitute to cold anesthesia in experiments assessing mosquito heart function or immune competence. Moreover, these data also illustrate the intricate biology of the insect heart. Specifically, they confirm that the neurohormone CCAP modulates heart rhythms and that it serves as an anterograde pacemaker.

Mild hypothermia facilitates the expression of cold-inducible RNA-binding protein and heat shock protein 70.1 in mouse brain

An appropriate thermal control system is essential for maintaining brain homeostasis. Hypothermia is a decrease in core body temperature that occurs when the thermoregulatory responses of homeothermic animals are impaired by environmental and situational influences, such as cold ambience and anesthesia. In recent years, hypothermia has been used for medical treatment, i.e., therapeutic hypothermia, for patients with stroke, traumatic brain injury, and heart surgery. However, the target molecules acting during hypothermia have not been identified. To understand the molecular mechanisms, we generated a mouse model of mild hypothermia (1°C–2°C below normal), and analyzed the expression of several genes. After mice were exposed to cold for 24 and 48h, their rectal temperature reached 33°C–35°C. Then, using real-time quantitative PCR, we analyzed the mRNA expression levels of c-fos, cold-inducible RNA-binding protein (CIRP), heat shock protein (hsp) 70.1, oxytocin, and representative inflammatory cytokines, i.e., tumor necrosis factor (TNF)-α and interleukin (IL)-6 in target organs. Importantly, we found that the expression levels of CIRP and hsp70.1 were elevated in the olfactory bulb within 48h. In the hypothalamus, CIRP expression levels increased and were followed by an increase in hsp70.1 expression. Meanwhile, TNF-α and IL-6 expression decreased gradually over 24 and 48h in the olfactory bulb and hypothalamus. These specific expression profiles, i.e., enhanced CIRP and hsp70.1 expression and depressed cytokine expression, suggest that they could regulate apoptosis related to the cytokine signaling.

Characterization of neural network reorganized by peripheral deafferentation in SI cortex and VPL thalamus of anesthetized rats

Partial blocking of a sensorγ transmission from the periphery to the central nervous system by amputation. cold block and local anesthesia induces immediate somatotopical reorganization at multiple levels of the somatosensorγ system of adult mammals. The emergence of new receptive field (RF) or expansion of RF to RF boundary (RFB) after temporary deafferentation (TD) by local anesthesia has been suggested to be mediated with synaptic correlation among neurons. In this study, we characterized the alteration of neural network among neurons in each area during TD. TD induced the suppression of excitatorγ postsynaptic activities triggered by RF center (RFC) neurons，while those by RFB and RF outside (RFO) neurons in both SI cortex and VPL thalamus increased during TD. The quantification of neuronal activities changed during TD strongly suggests that the reorganization in SI cortex is more conspicuous than that in VPL thalamus. This means that TD-induced suppression of RFC activities may primarily lead the facilitation of RFB and RFO neurons, functionally disinhibiting the lateral inhibition among neurons.

Chill out: cooling promotes aggressive behavior in the ant Formica xerophila

Studies of insect behavior often involve cooling individuals prior to performing experiments or making observations. For such studies, it is important to know how cooling might affect subsequent behavior. Here I investigate how anesthetization by cooling (relative to anesthetization by carbon dioxide or control individuals) affects the aggressive behaviors of two closely related ant species, Formica xerophila and F. integroides. These species regularly compete for resources, and individuals of both species regularly experience nighttime temperatures similar to those of cold-induced anesthetization. I show that cooling increases aggression (toward both interspecific competitors as well as nestmates) for F. xerophila, but has no effect on F. integroides behavior. Although previously cooled F. xerophila are more aggressive during both intraspecific and interspecific interactions, intraspecific fights are much shorter in length than interspecific fights. Furthermore, aggression by F. xerophila decreases as time since being cooled increases. These data suggest that cooling produces a short-term reduction in the ants’ discriminatory abilities, which leads to mistaken identities during encounters. The difference in species’ behaviors after cooling can be attributed to their differences in strategies when encountering potential competitors. Results here confirm that cold anesthesia can affect subsequent behavior, and needs to be tested in behavioral studies with insects.

Spinal cord injury in neonate rats alters respiratory neural output via supraspinal mechanisms

The primary cause of mortality in spinal cord injured patients is respiratory insufficiency. Upper cervical spinal cord injury (SCI) interrupts descending respiratory motor drive, altering ventilation. Alterations in breathing patterns after SCI are dependent on peripheral feedback mechanisms; however, it is not clear whether supraspinal plasticity also occurs. Alterations in respiratory frequency after SCI could suggest supraspinal plasticity since respiratory frequency is controlled at the brainstem level. We hypothesized that SCI may induce supraspinal respiratory plasticity in rats. Therefore, we examined the effect of C2 hemisection in neonate rats on the respiratory-like motor output of brainstem-spinal cord preparations. On postnatal day (P)0 or 1, a C2 hemisection surgery was performed under ketamine/xylazine and cold anesthesia. On P3, P4, or P5, rats (hemisected and littermate controls) were deeply anesthetized with halothane and brainstem-spinal cords removed. Respiratory-related activity was recorded from C4 ventral roots while the pH of the superfusate was changed (pH 7.2, 7.4 and 7.8). Respiratory-like frequency was significantly increased as pH was decreased in both hemisected (n=6) and controls (n=6) (p<0.001). The frequency of respiratory-like neural discharge was significantly reduced in hemisected rats compared to controls at all pH values (p=0.015). These data suggest that SCI does not alter the sensitivity to pH, but that supraspinal plasticity of the respiratory system occurs in neonate rats since the frequency of the in-vitro preparation was significantly altered. The mechanisms underlying this supraspinal respiratory plasticity after SCI remain unknown. This research was supported by NIH grant HD 31550