Annual Cycle Of Activity Research Articles

Endogenous circannual rhythms and photorefractoriness of testis activity, moult and prolactin concentrations in mink (Mustela vison).

Mink are seasonal photosensitive breeders; testis activity is triggered when days have less than 10 h light. Increasing and decreasing plasma concentrations of prolactin induce the spring and autumn moults. In a 5 year experiment, males were maintained under short days (8 h light:16 h dark) at 13 degrees C or long days (16 h light:8 h dark) at 21 degrees C, winter and summer conditions, respectively. Under winter and summer conditions, circannual cycles of prolactin secretion and moulting were observed at intervals of about 11 months. Recurrence of testis cycles was not evident. In a second experiment, males were maintained under an 8 h light:16 h dark cycle from the winter solstice or under 10 h light:14 h dark, 12 h light:12 h dark or 14 h light:10 h dark cycles from 10 February. Under 8 h light:16 h dark cycle, testis regression was slightly later than under natural conditions, indicating photorefractoriness. However, mink remained sensitive to light: the longer the photoperiod, the faster the testis regression. In a third experiment, males were transferred under 8 h light:16 h dark or 16 h light:8 h dark from 15 May (group 1), 12 June (group 2) or 4 July (group 3); males submitted to long days received melatonin capsules on the day of transfer. Increasing concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) and testis volume were shown by half the males in group 2 and nearly all the males in group 3; the constant release of melatonin from implants was more efficient than short days; but in the three groups, prolactin concentrations decreased in the few days after short-day or melatonin treatment. Overall, the results demonstrate endogenous circannual rhythms of prolactin secretion, body weight and moulting. Although a refractory period to short days was observed, the annual cycle of testis activity totally relies on the annual changes in daylength.

Annual variations in the binding of insulin to hepatic membranes of the frog Rana esculenta

Amphibia undergo regular annual cycles of metabolic activity that are influenced by both exogenous factors and hormones. Insulin binding to crude frog hepatic membranes was studied throughout the year. The general character of insulin binding was similar to that in other vertebrates; the maximum specific binding was achieved after 4 hr at 4°, the optimum pH was 7.8, half-maximal displacement of bound insulin was from 9 × 10 −10 to 1 × 10 −9 M, and insulin analogs competed for the insulin receptor in line with their relative biological potencies. A biphasic Scatchard plot and negative cooperativity of the receptor were also observed in frog liver membranes. Affinity constants from Scatchard plots revealed high and low affinity binding sites which were unchanged during the year. The seasonal cycle, however, markedly affected the binding capacity for both sites. Maximum binding occurred in May–June and the minimum in November–December for both classes of receptors. Binding capacities ranged from 1.71 to 11.33 fmol/mg protein for the high affinity sites and from 432 to 3171 fmol/mg protein for the low affinity sites. It is concluded that annual cycles of insulin binding reflect modulation of receptor number rather than receptor affinity.

Neuropeptide Y-like immunoreactivity in the diencephalon of the little brown bat (Myotis lucifugus): localized variations with physiological state.

The current study used light microscopic immunocytochemistry to demonstrate and compare neuropeptide Y-like immunoreactivity (NPY-IR) in the diencephalon of the little brown bat (Myotis lucifugus) at different stages in its annual cycle of activity and hibernation. Animals were sacrificed in each of three discrete physiological states: euthermic, hypothermic, and hibernating. In general, NPY-IR was abundant in the hypothalamus and sparse in other diencephalic areas. Immunoreactivity was present in a number of pathways which project to or originate from diencephalic nuclei; these include the ansa peduncularis, medial forebrain bundle, inferior thalamic peduncle, stria terminalis, stria medullaris, mammillary peduncle, and dorsal longitudinal fasiculus. Dense fiber plexuses were present throughout the hypothalamus; however, NPY-IR was conspicuously absent from the suprachiasmatic nucleus. Immunoreactive perikarya were located in the supraoptic, dorsomedial, ventromedial, and arcuate nuclei, in the external division of the ventral lateral geniculate nucleus, and in the pineal gland. Localized changes in density and/or distribution of NPY-IR were correlated with changes in physiological state.

The Annual Cycles of Activity and Weight of Rock Squirrels (Spermophilus variegatus) in Southeastern Arizona

-Rock squirrels (Spermophilus variegatus) were studied from July 1983 to June 1987 in an oak (Quercus sp.) savanna in southeastern Arizona. Adults were relatively inactive from late October through February. In the autumn, adult males generally were significantly less active (and immerged earlier) than females. Juveniles first appeared aboveground in July, and they were active throughout the autumn. Annual activity patterns of juvenile males and females did not differ. While adult males were significantly heavier than females in late May and early June, the middle of the mating season, there were no significant differences in mean weights between adult males and females during any other half-month period. Juvenile males and females emerged aboveground at similar weights and, thereafter, had similar rates of postemergent weight gain.

Hormones and behaviour: A joint examination of studies on seasonal variation in song production and plasma levels of testosterone in the Great TitParus major

The annual cycle of song activity according toAlexander (1935) and data compiled byBezzel (unpublished data) are compared with the annual course of testosterone plasma levels in free-living male Great Tits ascertained byRohss S this can probably also be said of the higher song activity at the same time of the season.

Nuclear size and shape changes in fusiform cambial cells of Abies balsamea during the annual cycle of activity and dormancy

Interphase, prophase, and telophase nuclei were measured at different times during the year in fusiform cambial cells located at the base of the main stem of 6-year-old trees and in 1-year-old shoots from the top of 21-year-old trees. In both materials, the size and shape of nuclei exhibited seasonal changes that were independent of the cell cycle. Nuclear length was greater, whereas nuclear width and depth were smaller, when the cambium was dormant than when it was active. Nuclear volume gradually declined during the growing period and increased during the rest stage of dormancy. Nuclei had the highest surface to volume ratio in the quiescence stage of dormancy. During cambial activity, the projected area of prophase nuclei decreased, whereas it did not change for telophase nuclei. Nuclear volumes from the present investigation were combined with nuclear DNA contents previously recorded to estimate seasonal changes in nuclear DNA concentration which appear to be associated with the annual cycle of cambial activity and dormancy. Key words: balsam fir, periodicity, nucleus, xylogenesis, rest.

Microplitis croceipes (Hymenoptera: Braconidae) Diapause Response to Insectary Conditions

Annual cycles of activity and development occur across the class Insecta and have evolved as a strategy to avoid or exploit environmental extremes (Saunders 1982). Parasitoids, especially host-specific species, necessarily respond to seasonal activities, or occurrence, of their host. Understanding the seasonal relationship between agricultural pests and their parasitoids is important to understand the parasitoids' potential for biological control (Powell et al. 1989). To better understand the seasonal synchrony between Heliothis spp and Microplitis croceipes (Cresson), photoperiod and temperature studies were undertaken in the laboratory and insectary during 1984 and 1985 at the University of Arkansas. Diapause is induced in H. virescens by a photoperiod of 10:14 (L:D) and inhibited by a photoperiod of 14:10 (L:D) in a Louisiana biotype (Phillips & Newsom 1966). High temperature (270C) counters the effect of short daylengths. The sensitive stage is the larva, in which M. croceipes is endoparasitic. In the laboratory, M. croceipes demonstrates 50% diapause induction in response to a critical Light:Dark ratio of 10.30:13.30 (21?C) and 11.00:13.00 (18?C) (Brown & Phillips 1990). Temperature alone (15?C) also induces 100% diapause at a photoperiod of 14:10 (L:D). The M. croceipes larva is the sensitive stage and the diapausing stage is the prepupa. There is significant interaction between photoperiod and temperature in diapause induction. Development times from cocoon formation to adult emergence is highly variable. This variability may be favorable in that it allows M. croceipes to cope with erratic and unfavorable conditions during the spring when host populations may be low or seasonal climatic changes have not stabilized. For the insectary study, 20 H. virescens were reared to third instar at 24?C and 14:10 (L:D) photoperiod (non-diapausing conditions) in 180 ml waxed paper cups (rearing chamber) containing approximately 5 ml of pinto bean medium (Burton 1969). Parasitoids were reared from field-collected Heliothis spp. and held at 26C, 50% RH, and 14:10 (L:D) photoperiod. Hosts were exposed to the parasitoid by placing two 5-7 day-old M. croceipes females in the above rearing chamber for 8 h. Parasitized hosts were then transferred to individual 30 ml rearing cups containing pinto bean diet and placed in the insectary on different dates during a two year period (Table 1). The insectary was 3.7 by 6.1 by 2.4 m with vertical walls made of standard mesh screening material. Media cups containing the host and diet were placed in the insectory and observed on a biweekly basis until 22 December, when the parasitoid cocoons were removed. Cocoons were then placed in a 14:10 (L:D) (long day) photoperiod and 24?C regimen and monitored daily for emergence. Ambient temperatures and humidities in the insectary were recorded with a Model 594 Bendix Hygrothermograph (Bendix Environmental Science Division, Baltimore, Maryland 21204). Diapause response averaged 3.4% when the parasitized hosts were placed in the insectary in late August (Table 1). Diapause increased to 98.6% when hosts and parasitoids were placed in the insectary on 25 September. This 30 day period represents

Development of Thermoregulation and Torpor in the Golden-Mantled Ground Squirrel Spermophilus saturatus

Small mammals ectothermic at birth become endothermic when they weigh only 20–50% of adult body mass. Juveniles of several species show torpor shortly after endothermy is reached, and it appears that they conserve energy during food shortages to avoid starvation. We became interested in whether juveniles of a species with a marked annual cycle of hibernation and activity can enter torpor during the season in which adults remain homeothermic. Neonatal Spermophilus saturatus were ectothermic, and development of endothermy and thermoregulation required about 36 days. In summer, withdrawal of food and water did not induce torpor in endothermic juveniles. Only in fall, 2 weeks before all juveniles began hibernation with surplus food and water, could torpor be induced in some individuals by food and water deprivation.

Distribution of Indole-3-Acetic Acid and the Occurrence of Its Alkali-Labile Conjugates in the Extraxylary Region of Pinus sylvestris Stems

Free and conjugated indole-3-acetic acid (IAA) were measured by quantitative gas chromatography-selected ion monitoringmass spectrometry in the extraxylary region of the stem of large Pinus sylvestris (L.) trees during the annual cycle of cambial activity and dormancy. The extraxylary region at the stem top and bottom was divided into 3 and 4 fractions, respectively, for the free IAA measurements, while the entire extraxylary region was extracted when the IAA-conjugates were analyzed. The effect on the distribution pattern of expressing IAA level as a concentration (per gram fresh weight or dry weight) and as total amount (per square centimeter) was examined. The IAA level was much higher in the cambial region than in the fractions that contained the nonfunctional phloem and the periderm. The largest IAA concentration occurred in the fraction that included the cambium, whereas the total amount of IAA was greatest in the phloemcontaining fraction. The significance of the nonuniform radial distribution of IAA for estimating the IAA concentration in the cambial region is discussed in relation to how the cambial region is sampled. A slight Iongitudinal gradient in IAA concentration, decreasing from the top to the bottom of the stem, was observed in the cambial region when the cambium was in the grand period of activity, but not at the end of the cambial growing period. In all fractions, the total amount of IAA was highest when the cambium was active. However, the IAA concentration in the cambial region did not follow the same pattern, actually being lowest during the tracheid production period at the stem bottom. IAA conjugates were detected on all sampling dates except June 23, but their concentrations were always less than 14% of that of free IAA, and their occurrence did not obviously vary during the year. In general, there was a higher concentration of ester conjugates than of amide conjugates, and the ester conjugates were more abundant at the top of the stem than at the bottom.

Annual Activity and Weight Cycles of Bats in South-Eastern Tasmania

Activity and weight changes were studied over a year at an area in south-eastern Tasmania where all eight species of Tasmanian bats were present. Activity was lowest in winter and highest in spring. Low levels were recorded during December and January, probably due to heavy rain. High levels of activity in May coincided with mild temperatures and may have taken advantage of emergence of moths at this time. A greater proportion of Chalionolobus morio were caught from May to August in comparison with other species. Sex ratios of captured individuals differed significantly from parity for C. morio, Falsistrellus tasmaniensis, Eptesicus regulus and Nyctophilus geoffroyi. For C. morio, the proportion of males captured increased during the colder months. For E. regulus, the proportion of females caught increased asymptotically as the capture rate for this species increased. Weights of bats varied over the year. For female E. regulus and N. geoffroyi, weight peaked in late pregnancy and dropped over winter, but for C. morio weight was similar at the end of autumn and early spring. For male E. regulus, weights were highest in autumn and showed no decline over winter, but for C. morio weights were greatest during mid-winter. C. morio is more active than other bats during colder periods and may rely on reduced competition with other species at these times to build up fat reserves.

Ciclos estacionales de actividad y modelos espaciales en las poblaciones de Coleoptera tenebrionidae de las dunas costeras de la playa de El Saladar (Alicante-Elche, SE. de España)

SUMMARY The annual activity cycles and the patterns of spatial distribution of four species of Coleopte­ ra Tenebrionidae : Pimelia modesta Hbst., Erodius carinatus Sol., Tentyria elongata Walt, and Pachychila fioli Sol., were studied by means of pitfall traps at a coastal dune near Alicante (SE Spain). Three species (Pimelia modesta, Tentyria elongata and Pachychila frioli) showed long

An investigation of the Annual Cycle of Convective Activity over the Tropical Americas

Abstract Outgoing longwave radiation (OLR) is used to describe the annual cycle of convection that resides over the Amazon Basin during austral summer and over Central America and the adjacent waters of the Pacific during austral winter. The preferred locations of the convective activity during the wet season in the respective hemispheres are determined, and the beginning and ending of these seasons is specified. The onset of the wet season over Amazonia usually occurs within a single month, while the onset of the wet season over Central America typically requires from one to three months. The annual cycle of convective activity in this regime is shown to exhibit a seasonal regularity and degree of symmetry with respect to the equator which exceeds those characterizing the other two annually varying regimes in the tropical belt. Analyses produced by the European Centre for Medium-range Weather Forecasts (ECMWF) are superimposed upon OLR fields to illustrate features of the atmospheric circulation in the v...

Seasonal fluctuations of estrogen-binding activity in the testis of the frog, Rana esculenta

We have studied the annual cycle of estrogen-binding activity in the frog, Rana esculenta, testis to evidence possible fluctuations. The testicular binding for [ 3H]estradiol-17β shows high affinities (cytosolic K d = 1.94 ± 0.43 × 10 −9 M; nuclear K d = 2.72 ± 1.20 × 10 −9 M) and low capacity (cytosolic: 7.56 ± 0.66 fmol/mg protein; nuclear: 9.27 ± 2.5 fmol/mg protein). Nuclear-binding activity appears in spring concomitantly with the estradiol peak in plasma and testes, while, in the remaining periods, binding capacity was extremely low or absent. Present data strongly support an important role played by estrogens as an intratesticular control factor in vertebrates.

Seasonal variation in body weight, fat, and behavior of California ground squirrels (Spermophilus beecheyi)

Annual cycles of activity and reproduction were documented in a population of California ground squirrels (Spermophilus beecheyi) in coastal California. Behavior, body mass, and reproduction were monitored in marked individuals between November 1983 and January 1986 through regular focal animal observation and livetrapping. Mass measures for reproductive tracts and gonadal fat pads were concurrently collected from a separate population of animals sacrificed in the laboratory. Mass and feeding behavior varied with sex and age. Surface activity, body weight, fat pad mass, and food consumption appeared to be closely related in this population. Fat pad mass was greater in nonreproductive than in reproductively active members of both sexes, as was body mass among males. Female body mass was greatest during pregnancy. Comparisons among reproductive status groups within each sex revealed significant differences in feeding, resting, vigilance, locomotor activity, and social behavior. Comparison with other populations suggested that S. beecheyi is highly variable with respect to demography, seasonal activity, timing of reproduction, and social behavior.

Impact of atmospheric dispersion and transport of viral aerosols on the epidemiology of influenza.

Current theories of influenza viral epidemiology have not explained the persistence, seasonality, and explosive outbreaks of virus over large geographic areas. It is postulated in this paper that atmospheric dispersion and intercontinental scale transport of airborne aerosolized influenza virus may contribute to the spread, persistence, and ubiquity of the disease, the explosiveness of epidemics, and the prompt region-wide occurrence of outbreaks and that seasonal changes in circulation patterns and the dispersive character of the atmosphere may help to explain the regular annual cycle of influenza activity.

Melatonin mediates alternation of seasonality in Syrian hamsters.

The annual cycle of reproductive activity in the Syrian hamster, Mesocricetus auratus, is the result of interaction between seasonal changes in daylength (photoperiodism) and seasonal changes in responsiveness to daylength (seasonality). The present experiment was designed to investigate the role of the pineal gland and its hormone, melatonin, in the alternation of seasonality (scotosensitivity and scotorefractoriness). Male hamsters were maintained on short daylengths (10L:14D) to establish scotorefractoriness, and then they were transferred to long daylengths (14L:10D) for conversion to scotosensitivity (sensitive to short daylengths). Before transfer to long daylengths, some of the hamsters were pinealectomized and others were sham-operated or unoperated. Some of the pinealectomized hamsters received single daily melatonin or saline injections while on long daylengths. After 14 wk on long daylengths, the hamsters were transferred to short daylengths for 10 wk to test for conversion to scotosensitivity. Pinealectomized hamsters were given three daily melatonin injections while on short daylengths. Such treatment is known to promote gonadal regression in scotosensitive but not in scotorefractory hamsters. Examination of testes after the short daylength interval revealed that exposure of nonpinealectomized hamsters to long daylengths had reestablished scotosensitivity (regressed testes). Pinealectomized hamsters that received no melatonin replacement while on long daylengths remained scotorefractory (enlarged testes), whereas those that received single daily injections of melatonin during long daylengths were found to be scotosensitive. These results indicate that a daily pulse of melatonin during expsoure to long daylengths has an important role in reestablishing responsiveness (scotosensitivity) to short daylengths.

On testing temporal niche differentiation in carabid beetles.

It is first shown that den Boer's (1985) claims that competition should be rejected as a factor explaining community structure are not warranted by his tests on temporal niche differentiation in carabid beetles. The power of these tests is so low that they are unlikely to detect even the most extreme pattern of niche differentiation. A major factor that affects their power is the procedure of building up an artificial species pool from the local communities to which the test is to be applied. Alternative tests are then presented, and applied to data on annual activity cycles of carabids in three forest biotopes in Belgium. Three factors are shown to strongly affect their outcome: the unit into which the time scale is divided, the criteria used to incorporate constraints, and the set of species selected. Nevertheless, they provide some evidence that there is a growing niche differentiation from the successional to the climax forest, as predicted by competition theory. Other hypotheses, however, could explain the observed pattern.

Aquatic Microannelids (Oligochaeta and Aphanoneura) of Underground Waters of Southeastern New York

We investigated the distribution of aquatic oligochaetes and Aeolosoma in the hyporheic zone and other underground habitats in southeastern New York. Twenty-four species of oligochaetes were found, exclusive of the Enchytraeidae, which could not be identified to species. Two of the species, Rhyacodrilus cf. subterraneus and Chaetogaster cf. krasnopolskiae, are reported for the first time from North America. Most of the oligochaetes found in underground waters are widespread in surface waters as well. Annual cycles of abundance and reproductive activity of five abundant taxa are described; these cycles are similar to those of the oligochaetes from lakes and streams. INTRODUCTION The underground waters of North America remain largely unexplored biologically, despite the economic importance of groundwaters, the ecologically significant connections between groundand surface waters (e.g, Hynes, 1983) and the demonstration by European zoologists that underground waters contain rich and often distinctive faunas (Delamare Deboutteville, 1960; Botosaneanu, 1986). Notable exceptions include ecological and evolutionary studies of the macroscopic animals of caves (Culver, 1982; Barr and Holsinger, 1985), investigations into the systematics of some of the larger invertebrates (e.g, Holsinger, 1978; Herschler and Longley, 1986) and an increasing body of ecological works on the hyporheic macrobenthos of streams (Williams, 1984). Reported here are some of the results of a survey of the invertebrate fauna of the shallow groundwaters of southeastern New York. The goals were to describe the composition of the invertebrate communities, the natural history of their dominant members and to make comparisons with invertebrate communities of groundand surface waters elsewhere. Because of technical difficulties in sampling the fauna of underground waters, this study was limited to shallow groundwaters and zones of contact between underground and surface waters, such as gravel bars associated with streams, seeps and springs, rather than deep groundwater. STUDY AREA Most samples came from Dutchess or Ulster counties in southeastern New York. Single sites in nearby Litchfield Counsy, Connecticut, and in Columbia County, New York, were visited. Most of the area is underlain by shales of Ordovician age. Consequently, most surface waters in the region are hard (pH = ca. 8; Ca44 = 0.5 to 1 meq/ liter) and fertile. There are a few outcrops of limestone and, in Ulster County, a large exposure of a hard Silurian quartzite conglomerate that forms the Shawangunk Mountains. Waters on the Shawangunks are soft and acid (pH = 4 to 6; Ca44 = 0.02 to 0.2 meq/liter), in marked contrast to surrounding areas. The entire study area was glaciated. Most samples were taken from gravel bars along or beneath streams (the hyporheic zone, habitat type Li of Botosaneanu, 1986). These sites are fed largely by stream water, because the water temperature in such sites was typically only 1-3 C cooler than stream water during the summer and 1-2 C warmer than stream water during the winter. However, many of these sites receive lateral seepage from nearby slopes as well. Other samples were taken from seeps (habitat N, the hypotelminthorheic, of Botosa'Present address: 65 Linnmoore Street, Hartford, Connecticut 06114.

An annual cycle of abundance and activity of heterotrophic bacteria and abundance of hydrocarbonoclastic bacteria in Newfoundland coastal water

An annual cycle of abundance and activity was determined for bacteria in Newfoundland coastal water that is dominated by the Labrador Current. Both in abundance and activity, the population showed characteristics similar to those reported for bacteria in cold ocean environments. The number of bacteria per litre determined by the acridine orange direct count method ranged from an average low of 0.25 × 108 in winter to an average high of 2.8 × 108 in summer. Activity, determined by the kinetic method, was correlated with temperature. The average heterotrophic potential (Vmax) was 3 ng glutamate. L−1∙h−1 in winter and 54.7 ng glutamate. L−1∙h−1 in summer. The average turnover times were 2632 and 256 h, respectively, during the same periods. The population of hydrocarbonoclastic bacteria, estimated by a most probable number method, constituted 4.4% of the viable bacterial population estimated by the standard plate count method, although the former were most abundant near the water's surface. The number of hydrocarbonoclastic bacteria was correlated with temperature and with Vmax of the heterotrophic bacterial population.

An annual cycle of abundance and activity of heterotrophic bacteria and abundance of hydrocarbonoclastic bacteria in Newfoundland coastal water : Powell, J.C., P.E. Dabinett and J.A. Gow, 1987. Can. J. Microbiol., 33(5):377–382

An annual cycle of abundance and activity of heterotrophic bacteria and abundance of hydrocarbonoclastic bacteria in Newfoundland coastal water : Powell, J.C., P.E. Dabinett and J.A. Gow, 1987. Can. J. Microbiol., 33(5):377–382