Insights into torpor and behavioural thermoregulation of the endangered Juliana's golden mole

The cryptic, subterranean ways of golden moles (Chrysochloridae) hamper studies of their biology in the field. Ten species appear on the IUCN red list, but the dearth of information available for most inhibits effective conservation planning. New techniques are consequently required to further our understanding and facilitate informed conservation management decisions. We studied the endangered Juliana's golden mole Neamblysomus julianae and aimed to evaluate the feasibility of using implantable temperature sensing transmitters to remotely acquire physiological and behavioural data. We also aimed to assess potential body temperature ( T _b) fluctuations in relation to ambient soil temperature ( T _a) in order to assess the potential use of torpor. Hourly observations revealed that T _b was remarkably changeable, ranging from 27 to 33 °C. In several instances T _b declined during periods of low T _a. Such 'shallow torpor' may result in a daily energy saving of c . 20%. Behavioural thermoregulation was used during periods of high T _a by selecting cooler microclimates, while passive heating was used to raise T _b early morning when T _a was increasing. In contrast to anecdotal reports of nocturnal patterns of activity, our results suggest that activity is flexible, being primarily dependent on T _a. These results exemplify how behavioural patterns and microclimatic conditions can be examined in this and other subterranean mammal species, the results of which can be used in the urgently required conservation planning of endangered Chrysochlorid species.     

Reproductive investment in the Silurus meridionalis

A comparison of pre- and postspawning Silurus meridionalis showed that 20·7% of body stored energy was utilized during spawning for a standard male (74·5 cm) and 23·8% for a standard female (85·3 cm). About one-third of the loss of the stored energy was released as eggs by females, and almost all of the energy loss for males and about two-thirds for females were expended in metabolism. Stored lipid as fuel for metabolism supplied 90·0% of energy in males and 95·2% in females, and protein supplied the rest of the energy. Models for predicting energy in released gametes ( G _g), deposited in the body as somatic growth ( G _s), utilized in spawning activity ( S _a), expended in maintenance ( M , including metabolism, faeces and excretion), and food energy ( C ) were developed, and annual energy budgets were compiled. The balanced budget for a male aged 4 was: 100 C =0·06 G _g+11·17 S _a+19·5 G _s+69·2 M , and for a female aged 5: 100 C =5·48 G _g+8·51 S _a+15·8 G _s+70·2 M .     

Roles of endothermy in niche differentiation for ball-rolling dung beetles (Coleoptera: Scarabaeidae) along an altitudinal gradient

Abstract.  1. An analysis of whether niche differentiation in ball-rolling dung beetles can be explained by the way in which they regulate their body temperature was conducted.
2.  A priori assumptions were: (i) if thermoregulation affects niche partitioning, sympatric species must have different endothermic strategies that minimise encounters; or, alternatively (ii) if two co-occurring species show the same thermoregulation pattern and their flight periods overlap, they might be avoiding competition by exhibiting different resource preferences or different food relocation behaviour.
3. The ball-rolling dung beetles studied showed a hierarchical structure based on the species' endothermic capacity, measured as temperature excess [ T _ex= difference between body temperature ( T _b) and ambient temperature ( T _a)]. Those with a high T _ex (10–15 °C) were located exclusively at altitudes >1000 m a.s.l. On the coastal plains, species with a high T _ex were restricted to flying at night when the T _a was lower. Species with a lower T _ex (less than 10 °C higher than T _a) were found in the coastal plains zone.
4. Where there was sympatry with similar trophic habits, the species involved showed very different thermal niches, and where there was significant overlap of thermal niches between sympatric species, trophic habits of species were very different.
5. The results suggest that it is possible to use the concept of the thermal niche as a tool to explain interspecific interactions and the spatial distribution of species.     

Responses of a Specialized Insectivorous Mammal (Myrmecophaga tridactyla) to Variation in Ambient Temperature1

This study reports the effect of daily mean ambient temperature on daily activity and habitat use by the giant anteater (Myrmecophaga tridactyla) in the Pantanal wetlands of Brazil. We equipped 11 giant anteaters with a global position system collar programmed to acquire a location every 10 min for 15 d. A temperature data logger left in the meteorological station at the study site registered data on ambient temperature. Giant anteaters were mainly active in open fields except during the coldest days, when they sought protection inside forests. Giant anteaters also used open habitats for resting but during the hottest or chilliest days they sheltered in forests. In the Pantanal, where temperatures are usually high, giant anteaters were active all night long, but as daily average ambient temperature decreased anteaters began and finished activity progressively earlier and reduced total activity. As a consequence, time spent active at daylight increased progressively and time spent active during the night decreased progressively, probably to allow the anteaters to expose themselves to solar radiation and to avoid heat loss during the night.     

Competition between anoxygenic phototrophic bacteria and colorless sulfur bacteria in a microbial mat

Abstract The populations of chemolithoautotrophic (colorless) sulfur bacteria and anoxygenic phototrophic bacteria were enumerated in a marine microbial mat. The highest population densities were found in the 0–5 mm layer of the mat: 2.0 × 10⁹ cells cm⁻³ sediment, and 4.0 × 10⁷ cells cm⁻³ sediment for the colorless sulfur bacteria and phototrophs, respectively. Kinetic parameters for thiosulfate-limited growth were assessed for Thiobacillus thioparus T5 and Thiocapsa roseopersicina M1, both isolated from microbial mats. For Thiobacillus T5, growing at a constant oxygen concentration of 43 μmol l⁻¹, μ_max was 0.336 h⁻¹ and K _s 0.8 μmol l⁻¹. Phototrophically grown Thiocapsa strain M1 displayed a μ_max of 0.080 h⁻¹ and a K _s of 8 μmol l⁻¹ when anoxically grown under thiosulfate limitation. In a competition experiment with thiosulfate as electron donor, Thiocapsa became dominant during a 10-h oxic/14-h anoxic regimen at continuous illumination, despite the higher affinity for thiosulfate of Thiobacillus .     

Influence of ambient and thoracic temperatures upon sexual behaviour of the gypsy moth, Lymantria dispar

ABSTRACT. In an ambient temperature ( T _a) range of 18–28°C, thoracic temperatures ( T _th) of individual male Lymantria dispar (L.), caught at flight in the field, ranged from 21 to 36.5°C, with a correlation coefficient of 0.63 between T _th and ambient temperature ( T _a). Ambient temperature (and insolation) altered the insect's body temperature and the probabilities, latencies, and durations of preflight responses to pheromone. In a wind tunnel at 16 and 20°C, quiescent males exposed to pheromone raised their T _th by sustained wing fanning from 17 and 21°C, respectively, to c. 24°C before takeoff. At 24 and 28°C ambient, T _th rose by takeoff to 28 and 31°C, respectively. The latencies of male wing fanning in response to pheromone decreased from 1.44 min at 16°C ambient, to 0.58 min at 20°C, to 0.26 min at 24°C, and to 0.16min at 28°C. The components of behaviour (antennal twitch, body jerk, step and wing tremor) that occurred between quiescence and wing fanning were more frequent at ambients of 16 and 20°C than at 24 and 28°C.     

Prolonged and daily torpor in the feathertail glider, Acrobates pygmaeus (Marsupialia: Acrobatidae)

Deep and prolonged torpor in marsupials is only known from the pygmy possums, family Burramyidae. We investigated the pattern of torpor in the feathertail glider Acrobates pygmaeus (Acrobatidae) to determine whether members of other marsupial families also possess the ability of remaining torpid for several days with body temperatures (T_b) approaching 0°C. At high air temperatures (T_a) of 15 and 20°C, A. pygmaeus usually exhibited daily torpor. Torpor bouts at T_a 12°C usually lasted for about 2˙5 days and at T_a 8°C up to 5˙5 days. The metabolic rate during torpor was reduced to about 1% of that in normothermic, resting individuals. The T_b during torpor was regulated at about 2°C when T_a fell below about 0˙8 °C. Arousal from torpor was rapid and the mean fastest rewarming rate was 0˙88°C/min. While A. pygmaeus exhibited deep and prolonged torpor, its pattern differed somewhat from deep hibernation. Acrobates pygmaeus did not show prehibernation fattening and a subsequent prolonged hibernation period and it appears that prolonged torpor is used only in emergency situations.     

Thermoregulation, energy metabolism, and torpor in blossom-bats, Syconycteris australis (Megachiroptera)

Since little information is available on torpor in bats of the suborder Megachiroptera, we investigated whether the small (18 g) blossom-bat Syconycteris australis displays torpor in the laboratory. Bats entered daily torpor when food and water were withheld for one night and the air temperature (T_a) was below about 26°. Torpor began shortly after lights went on in the morning and lasted for a maximum of 12 hours. During torpor at T_a18°, metabolic rates fell to a minimum of about 15% of that in resting individuals at the same T_a, and to about 40% of the basal metabolic rate. The body temperature (T_b) during torpor was metabolically defended at or above about T_b 18°. Individuals that did not enter torpor in the morning reduced their T_b from about 34.5°, observed in resting individuals that had been fed during the previous night, to values between 30.2 and 32.8°, and the resting metabolic rate fell by about 25%. The ability to undergo short periods of torpor may explain why the distribution range of S. australis extends much further south than that of other small Australian megachiropteran bats.     

Human Lymphocyte Proliferation: Dna Synthesis Time

Abstract. The DNA synthesis time ( T _s) of lymphocytes from spleens and lymph nodes of patients with Hodgkin's disease was determined by the double labeling method. ³H-TdR was administered in vivo and removed tissues minced in ¹⁴C-TdR in vitro. Lymphocytes from patients with lymphosarcoma and reticulum cell sarcoma were studied in a similar manner. Lymphocytes were divided into A cells, small with non-basophilic cytoplasm, B cells, small with basophilic cytoplasm, C cells, large with non-basophilic cytoplasm, and D cells, large with basophilic cytoplasm.
The T _s of splenic lymphocytes, in four samples not containing Reed-Sternberg cells, in hours, was: B 11.3; C , 7.9; D , 8.4; combined, 8.8. the T _s of B lymphocytes was significantly longer than that of C and D lymphocytes. A lymphocytes did not label sufficiently to measure T _s. C and D lymph node lymphocytes and lymphocytes in tissues containing Reed-Sternberg cells had a longer T _s than splenic C and D cells. the former was: B , 12.7; C , 11.7; D , 11.0; combined, 11.8. the latter was: B , 12.2; C , 11.3; D , 11.2; combined, 11.6. the T _s of Reed-Sternberg cells in one specimen of a splenic Hodgkin's tumor was 13.1 hr. Macrophage T _s was 10.7 and 15.1 hr. Lymphosarcoma cell T _s was 14.2 and 14.6 hr. Reticulum cell sarcoma cell T _s was 7.5 and 7.7 hr.
The following minimum times were calculated from observation of ³H-TdR only labeled mitotic figures: S to prophase, 71 min; S to metaphase, 75 min; S to telophase, 100 min.     

Proliferation kinetics of plasma cells and of normal haemopoietic cells in multiple myeloma

Abstract. DNA synthesis time ( T _s) and ³H thymidine (TdR) labelling index (LI) of bone marrow (BM) myelomatous plasma cells (PC) and of the residual haemopoietic cell population (RHCP) were measured by in vitro quantitative ¹⁴C-TdR autoradiography in five patients with multiple myeloma (MM) in different phases of disease (three at presentation and two at relapse) and in one patient with solitary extra-osseous myeloma. One other patient with plasma cell leukaemia (PCL) was studied during an initial relapse phase and later during the leukaemic terminal phase. PC T _s was 18.8 ± 3.7 (from 13.3 to 25.0) hr and PC LI was 2.5 ± 1.8%; (from 1.0 to 6.3%). In the case of PCL, circulating PC had a T _s of 14.4 hr and a LI of 3.1. From these experimental measurements, the fractional turnover rate (FTR—percentage of cells produced per unit time) and the potential doubling time ( T _d) of BMPC were calculated assuming that all BMPC were in a steady-state at the time of the study. BMPC FTR was 3.53 ± 2.3% cells per day (from 1.2 to 6.72) and BMPC T _d was 46.8 ± 27.5 days (from 15.0 to 75.4). Comparison with results obtained in BM blasts of children with acute lymphoblastic leukaemia (ALL) indicated that BMPC had a lower proliferative activity ( P < 0.001), although BMPC T _s was not significantly different. In two patients a tumour doubling time of 6 and 13 months was determined by clinical follow up. Comparison of this parameter with T _d showed a cell loss factor of more than 90% in both patients.
Kinetic data relative to RHCP showed slight variations with respect to those found in normal subjects, with a general tendency towards a prolongation of T _s and a reduction of LI.     

THE LYMPHOCYTES OF CHRONIC LYMPHOCYTIC LEUKEMIA: THEIR PROLIFERATION AND CELL CYCLE KINETICS

Lymphocytes obtained from CLL patients exhibited a delayed and reduced response to PHA when cultured in diffusion chambers. DNA synthesis (8–10 hr) and general time (15–19 hr) of the late-developing CLL blasts were consistent with normal values ( T _s: 8–10 hr; T _c: 14–17 hr). However, the G₂ period of CLL blasts seemed more variable, and their mitotic index during the response at 5–6 days was 30–50% of the values determined for normal blasts during their peak response at 2–3 days.     

The photosynthetic drought physiology of a diverse group of southern hemisphere conifer species is correlated with minimum seasonal rainfall

1. The instantaneous and integrated leaf gas exchange of 13 species of southern hemisphere conifers grown under identical glasshouse conditions were examined to determine whether there was any correlation between the characteristics of water use at the leaf level and environmental water availability.
2. In the conifer species examined, the minimum ratio of internal to ambient CO₂ measured in leaves during artificially imposed drought [( c _i/ c _a)_min] was strongly correlated with the minimum rainfall observed within the natural range of each species. This suggests that the distributions of these species are constrained by the drought tolerance of their photosynthetic apparatus.
3. A good correlation was found between the ratio of internal to ambient CO₂ measured in leaves under optimal conditions ( c _i/ c _a)_max and leaf δ¹³C (and hence inferred ∫[ c _i/ c _a]). Neither of these, however, correlated with the environmental parameters considered most likely to be limiting species distribution, i.e. precipitation and altitude.
4. These data suggest that decreasing water availability may have been the major factor responsible for the restriction and extinction of conifers in the southern hemisphere.     

Stomata of trees growing in CO2-enriched air show reduced sensitivity to vapour pressure deficit and drought

Stomatal conductance ( g _s) and photosynthetic rate ( A ) were measured in young beech ( Fagus sylvatica ), chestnut ( Castanea sativa ) and oak ( Quercus robur ) growing in ambient or CO₂-enriched air. In oak, g _s was consistently reduced in elevated CO₂. However, in beech and chestnut, the stomata of trees growing in elevated CO₂ failed to close normally in response to increased leaf-to-air vapour pressure deficit (LAVPD). Consequently, while g _s was reduced in elevated CO₂ on days with low LAVPD, on warm sunny days (with correspondingly high LAVPD) g _s was unchanged or even slightly higher in elevated CO₂. Furthermore, during drought, g _s of beech and chestnut was unresponsive to [CO₂], over a wide range of ambient LAVPD, whereas in oak g _s was reduced by an average of 50% in elevated CO₂. Stimulation of A by elevated CO₂ in beech and chestnut was restricted to days with high irradiance, and was greatest in beech during drought. Hence, most of the additional carbon gain in elevated CO₂ was made at the expense of water economy, at precisely those times (drought, high evaporative demand) when water conservation was most important. Such effects could have serious consequences for drought tolerance, growth and, ultimately, survival as atmospheric [CO₂] increases.     

Stomatal response to humidity: implications for transpiration

Abstract. Transpiration rates from apple leaves are analysed in terms of the ratio of latent heat flux (λ E ) to leaf net radiation ( Q ₁) and the climatological resistance ( r_i ). Increases in stomatal resistance with increasing leaf to air vapour pressure gradient ( D ), described by an empirical model, are incorporated in the analysis. This humidity effect causes the proportion of energy dissipated as latent heat to fall as Q ₁ increases, so that leaf transpiration rates in high energy environments are likely to be similar to those in lower energy environments. Boundary layer resistance ( r _a) exerts an increasingly important effect on transpiration rates as Q ₁ increases. At constant Q ₁ stomatal closure in response to increasing D results in very small changes in leaf temperature ( T ₁) across a wide range of ambient vapour pressure deficits (δ e ); r _a is then the major factor determining T ₁. The implications of these results are discussed.     

The effects of temperature and hyperoxia on arterial PO2 and acid-base status in Piaractus mesopotamicus

The effects of hyperoxia and change of temperature (range 20–30° C) on blood gases were studied in the teleost fish Piaractus mesopotamicus , native to several major river systems in Brazil. Large hyperoxia-induced increases of arterial P o₂ ( P _ao₂) indicated that true branchial blood shunts are negligible in relation to total gill perfusion. This implies that blood gases will be influenced by ventilation rather than by shunts. Acute variations of temperature ( t ) were accompanied by changes of arterial blood pH (on the average Δ p H_aΔt⁻¹ of — 0·015 units °C⁻¹), due mainly to alterations of P _aco₂: 2·4 mmHg at 20° C, 5·0 mmHg at 30° C. Concomitantly, P _ao₂ declined from 116 mmHg (20° C) to 89 mmHg (30° C). The data suggest that temperature-induced changes of acid-base status depend mainly on gill ventilation and that the decrease of P _ao₂ with higher temperature is a result of this regulation.     

DNA SYNTHESIS TIME IN LEUKAEMIC CELLS AS MEASURED BY THE DOUBLE LABELLING AND THE PERCENTAGE LABELLED MITOSES METHODS

Values of T _s provided by the double labelling method have been compared with those given by the percentage labelled mitoses curve for blast cells in the peripheral blood of a patient with plasma cell leukaemia and of rats bearing a transferable acute leukaemia. the double labelling method was carried out giving the first label (³H-thymidine) in vivo and the second label (¹⁴C-thymidine) in vitro with several values for the interval between the two labels. T _s was calculated by fitting regression lines to the results obtained. Data for percentage labelled mitoses were analysed by computer. For the plasma cell leukaemia values of T _s= 17.1 ± 7.0 hr and T _s= 19.8 ± 3.4 hr, and for the rat leukaemia values of 8.7 ± 1.7 hr and 9.0 ± 1.7 hr (7.1 hr corrected for exponential growth) were obtained from the percentage labelled mitoses and double labelling methods respectively. It is concluded that the double labelling method is valid for the study of cell proliferation in leukaemic blast cells.     

DOUBLE PULSE LABELLING WITH 3H-THYMIDINE: A METHOD FOR CALCULATING CELL POPULATIO KINETICS

A method was developed for calculating cell population kinetics with the aid of double pulse labelling with ³H-TdR. The labelling index was measured from auto-radiographs of the oral epithelium of two groups of 30-day-old rats. One group was injected once with ³H-TdR the other twice, with a time interval of 90 min between injections. DNA synthesis time was calculated from the equation:
   
where T _s= synthesis time; LI₁= labelling index in the single-injected group; LI₂= labelling index in the double-injected group; and T _i= time interval between injections. Synthesis time in the palate was 4.8 hr and 7.6 hr in the tongue. Generation time was calculated from the equation: T _g= ( T _s/LI₁) × 100, where T _g= generation time. Generation time in the palate was 46.1 hr and 75.8 hr in the tongue     

Correlations of stomatal conductance with hydraulic and chemical factors in several deciduous tree species in a natural habitat

Recent research in whole-plant stomatal physiology, conducted largely with potted plants in controlled environments, suggests that stomatal conductance ( g _s) might be more closely linked to plant chemical variables than to hydraulic variables. To test this in a field situation, seasonal g _s was examined in relation to a number of plant and environmental variables in 11 temperate, deciduous forest tree species. Stomatal conductance was generally better correlated with environmental variables (air temperature, vapor pressure deficit, PPFD) than with plant variables, and slightly better correlated with plant hydraulic variables (shoot water and osmotic potentials) than with plant chemical variables (xylem sap ABA concentration, xylem sap pH). We examined a model, developed previously for maize, which describes regulation of g _s by xylem sap ABA concentration with leaf water status acting to modify stomatal sensitivity to the ABA signal. This model explained slightly more variation in seasonal g _s in the forest trees than did single plant variables but not more variation than most single environmental variables. Response surface models, especially those incorporating environmental variables, were more consistently successful at explaining g _s across species.     

Molecular Cloning and Characterization of a Lobster Gαs Protein Expressed in Neurons of Olfactory Organ and Brain

Abstract: We have isolated from an American lobster ( Homarus americanus ) olfactory organ cDNA library a clone, lobGα_s, with >70% identity to mammalian and arthropod Gα_s sequences. In genomic Southern blots, a fragment of lobGα_s detected only one band, suggesting the lobsters have a single Gα_s gene. In brain and olfactory organ, lobGα_s mRNA was expressed predominantly in neurons, including many of the neuronal cell body clusters of the brain. Gα_s protein was also expressed broadly, appearing on western blots as a band of 51.8 kDa in brain, eyestalk, pereiopod, dactyl, tail muscle, olfactory organ, and aesthetasc hairs. These results suggest that lobGα_s plays a role in a wide variety of signal transduction events. Its presence in the olfactory aesthetasc hairs, which are almost pure preparations of the outer dendrites of the olfactory receptor neurons, and the expression of lobGα_s mRNA in the olfactory receptor neurons of the olfactory organ indicate that lobGα_s may mediate olfactory transduction. That virtually all ORNs express lobGα_s mRNA equally predicts that hyperpolarizing odor responses mediated by cyclic AMP are a property of all lobster olfactory receptor neurons.     

Responses of apple leaf stomata to environmental factors

Abstract. Stomatal conductances ( g _s) were measured on the leaves of 3–4 year old Golden Delicious trees and of seedlings of two other cultivars. Measurements were made on container grown trees in the field with a diffusion porometer in 1975 and 1976, and in controlled conditions in a leaf chamber in the laboratory in 1976. Stomatal densities in the Golden Delicious leaves were assessed from scanning electron micrographs. Stomatal density on extension shoot leaves was higher than on other leaf types after June.
The response to irradiance shown by both the porometer and the leaf chamber results could be described by a rectangular hyperbola: where g _max is maximum conductance and β indicates the sensitivity of g_s to photon influx density ( Q _p). The values of β were in the range 60–90 μmol m⁻² s⁻¹.
There was no evidence that apple stomata are sensitive to temperature per se, but g _s was reduced by increasing leaf to air vapour pressure deficits ( D ). There was a linear relationship between g _s and D which was not attributable to feed-back to leaf water potential (ψ_L) as the latter did not affect g _s until a threshold of about −2.0 to −2.5 MPa was reached. Conductance generally declined with increasing ambient CO₂ concentration.