Days Of Age To Adulthood Research Articles

Larval honey bees infected with Nosema ceranae have increased vitellogenin titers as young adults

Nosema ceranae is a pervasive and widespread honey bee pathogen that is associated with colony declines and has recently been shown to infect larval honey bees. In adult bees, Nosema infection is known to alter levels of a key protein, vitellogenin (Vg), which is necessary for egg-laying in queens, brood food production in workers, and proper immune function in all female bees. We therefore tested the effects of larval worker infection on hemolymph Vg titers. In 1-day old adult workers that were infected as larvae with 10,000 (10 K) or 40,000 (40 K) live N. ceranae spores/bee, Vg titers were significantly elevated by + 83% and + 73%, respectively, as compared to controls. At 7 days of adult age, Vg remained significantly elevated (+ 68%) in 10 K treated workers as compared to control workers. Nosema infection decreased total hemolymph protein titers in 1 and 7-day old adult bees (−50% in the 10 K and 40 K treated bees). Bees infected as larvae also had a more queen-like sting morphology. They developed slightly but significantly fewer barbs on their stings (−7% in the 40K-treated bees). Higher Vg levels are associated with younger bees. Thus, elevated Vg levels could delay normal age polyethism and disrupt colony balance.

Associative Learning during Early Adulthood Enhances Later Memory Retention in Honeybees

BackgroundCognitive experiences during the early stages of life play an important role in shaping the future behavior in mammals but also in insects, in which precocious learning can directly modify behaviors later in life depending on both the timing and the rearing environment. However, whether olfactory associative learning acquired early in the adult stage of insects affect memorizing of new learning events has not been studied yet.MethodologyGroups of adult honeybee workers that experienced an odor paired with a sucrose solution 5 to 8 days or 9 to 12 days after emergence were previously exposed to (i) a rewarded experience through the offering of scented food, or (ii) a non-rewarded experience with a pure volatile compound in the rearing environment.Principal FindingsEarly rewarded experiences (either at 1–4 or 5–8 days of adult age) enhanced retention performance in 9–12-day-conditioned bees when they were tested at 17 days of age. The highest retention levels at this age, which could not be improved with prior rewarded experiences, were found for memories established at 5–8 days of adult age. Associative memories acquired at 9–12 days of age showed a weak effect on retention for some pure pre-exposed volatile compounds; whereas the sole exposure of an odor at any younger age did not promote long-term effects on learning performance.ConclusionsThe associative learning events that occurred a few days after adult emergence improved memorizing in middle-aged bees. In addition, both the timing and the nature of early sensory inputs interact to enhance retention of new learning events acquired later in life, an important matter in the social life of honeybees.

Variations at a quantitative trait locus (QTL) affect development of behavior in lead-exposed Drosophila melanogaster

We developed Drosophila melanogaster as a model to study correlated behavioral, neuronal and genetic effects of the neurotoxin lead, known to affect cognitive and behavioral development in children. We showed that, as in vertebrates, lead affects both synaptic development and complex behaviors (courtship, fecundity, locomotor activity) in Drosophila. By assessing differential behavioral responses to developmental lead exposure among recombinant inbred Drosophila lines (RI), derived from parental lines Oregon R and Russian 2b, we have now identified a genotype by environment interaction (GEI) for a behavioral trait affected by lead. Drosophila Activity Monitors (TriKinetics, Waltham, MA), which measure activity by counting the number of times a single fly in a small glass tube walks through an infrared beam aimed at the middle of the tube, were used to measure activity of flies, reared from eggs to 4 days of adult age on either control or lead-contaminated medium, from each of 75 RI lines. We observed a significant statistical association between the effect of lead on Average Daytime Activity (ADA) across lines and one marker locus, 30AB, on chromosome 2; we define this as a Quantitative Trait Locus (QTL) associated with behavioral effects of developmental lead exposure. When 30AB was from Russian 2b, lead significantly increased locomotor activity, whereas, when 30AB was from Oregon R, lead decreased it. 30AB contains about 125 genes among which are likely “candidate genes” for the observed lead-dependent behavioral changes. Drosophila are thus a useful, underutilized model for studying behavioral, synaptic and genetic changes following chronic exposure to lead or other neurotoxins during development.

Mild heat stress at a young age in Drosophila melanogaster leads to increased Hsp70 synthesis after stress exposure later in life.

In a number of animal species it has been shown that exposure to low levels of stress at a young age has a positive effect on stress resistance later in life, and on longevity. The positive effects have been attributed to the activation of defence/cleaning systems (heat shock proteins (Hsps), antioxidases, DNA repair) or to effects of a changed metabolic rate, or both. We investigated the effect of mild stress exposures early in life on Hsp70 synthesis after a harder stress exposure later in life in five isofemale lines of Drosophila melanogaster. Female flies were either exposed to repeated bouts of mild heat stress (3 h at 34 degrees C) at a young age (days 2, 4 and 6 post-eclosion) or held under standard laboratory conditions. At 16 and 32 days of adult age, respectively, flies were exposed to a high-temperature treatment known to induce Hsp70 in the investigated species (1 h at 37 degrees C). Thereafter, the inducible Hsp70 levels were measured. Our data show a tendency towards increased Hsp70 synthesis with increased age for both 'mild stress' and 'no stress' flies. Moreover, the results show that flies exposed to mild stress at a young age synthesized more Hsp70 upon induction, compared to control flies, and that this difference was accentuated at 32 days compared to 16 days of age. Thus, bouts of mild heat stress at a young age impact on the physiological stress response system later in life. This may be caused by an increased ability to react to future stresses. Alternatively, the mild stress exposure at a young age may actually have caused cellular damages increasing the need for Hsp70 levels after stress exposure later in life. The importance of an Hsp70 upregulation (throughout life) in explaining the phenomenon of hormesis is discussed, together with alternative hypotheses, and suggestions for further studies.

Postnatal development of perisomatic GABAergic axon terminals on neurons projecting from area 17 to area 18 of the cat visual cortex.

We have studied the postnatal development of presumptive axon terminals (puncta) which were recognized by antibodies to the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) and were located on the somata of area 17 neurons projecting to the ipsilateral area 18 of the visual cortex in cats ranging from 7 days of age to adulthood. Projection neurons were retrogradely labeled by injection of horseradish peroxidase conjugated to wheat germ agglutinin into the ipsilateral area 18. These neurons were mainly pyramidal in shape at all the developmental stages examined and the adult distribution of labeled cells was reached by 21 days. Subsequent GABA postembedding immunohistochemistry using high-resolution light microscopy was carried out to study the development of GABAergic terminals on cell bodies of identified projecting neurons in layers II-III. At all ages examined, we found perisomatic GABAergic puncta on these cells. Their density showed a significant increase from postnatal days 7 to 45, and then remained largely constant through adulthood. Since GABAergic puncta are considered the light-microscopic correlate of GABAergic synaptic terminals, our results support the idea of a developmentally regulated increase in the inhibitory activity of local interneurons on area 17 pyramidal neurons projecting to area 18 in the cat visual cortex which occurs within the same time frame as that of the acquisition of the mature operation of these cells.

Changes with ageing in total dolichol and dolichol fractions in Drosophila

Since it is nuclear how the concentration of dolichol fractions change with ageing in mammals, we have examined the changes in another organism, Drosophila. Dolichol extracted from Drosophila melanogaster was found to consist of three fractions composed of 15, 16 and 17 isoprene units. The total dolichol content of female flies maintained at 25°C increased with ageing between 0 and 64 days of adult age but the change was not significant. The total dolichol content of male flies decreased with ageing but the decrease was not significant. The relative amounts of the three different dolichol fractions in both male and female flies also failed to show any significant ageing-related change. The greatest amount of dolichol was found in the 16 isoprene unit fraction representing 67.2% of the total dolichol in male flies and 65.4% in female flies. Increased dietary dolichol had little or no influence on the life span of Drosophila when given either during the developmental or adult stages.

Effect of shielding from environmental neutrons on the life span of Drosophila: Preliminary evidence

Shielding adult Drosophila melanogaster fruit flies from environmental neutrons with either paraffin wax or boric acid increased the median life span by between 4.6 and 9.7%. The increase in life span was significant only when the shielding began at 14–29 days of adult age. Shielding begun at 1 day of adult age did not result in a significant increase in life span. Shielding with boron during the reproductive, developmental and adult stages, however, resulted in a significant reduction of 11.9% in the median survival time. Environmental background neutrons, therefore, had surprisingly both a negative and positive influence on longevity depending upon the period of life when the exposure occurred.

Uric acid content of Drosophila decreases with aging

Free uric acid concentrations declined with aging in male Oregon R Drosophila melanogaster by 59% or more between 0 and 50 days of adult age. Free xanthine concentrations increased between 0 and 5 days of age and declined by 75% between 5 and 50 days of age. Xanthine oxidase activity was maximal for newly emerged flies and then declined rapidly reaching a minimum at 9 days of age. After 9 days of age xanthine concentrations may be the limiting factor for the production of uric acid by xanthine oxidase in aging fruit flies. Declining uric acid concentrations may represent a loss of antioxidant potential in aging Drosophila.

Calcium and calmodulin changes with aging in Drosophila

Total body calcium increased by 115% for Drosophila melanogaster (Oregon-R) males from 0 to 60 days of adult age at 25 °C. The highest values for total calcium were found during the pupal and larval developmental stages. The rate of calcium accumulation was dependent upon the environmental temperature at 11, 20, 25 and 30 °C. Feeding the calcium salts of carbonic, lactic and gluconic acid decreased the median life span at concentrations of 0.01 and 0.1M. Feeding calcium D-saccharate at a concentration of 0.1M did not change life span. At a concentration of 0.001M, none of the calcium salts altered life span. Feeding the calcium channel blockers diltiazem, felodipine, nifedipine and verapamil had little or no influence on life span. Other calcium antagonists, the diphosphonates, also failed to improve survival. Calmodulin concentrations declined during development and increased with aging during the adult stages but the increase was not significant. We conclude that high dietary intake of certain calcium salts can increase the rate of aging, but at moderate intakes calcium does not change the rate of aging of Drosophila. Calcium antagonists have little or no influence on the rate of aging of Drosophila.

Method for Determining Age Structure of Adult Populations of the Lesser Cornstalk Borer (Lepidoptera: Pyralidae)

Laboratory experiments were conducted to develop methods for determining age structure of Elasmopalpus lignosellus (Zeller) adults. Oöcyte development in the ovaries was used to establish five female classes:(1) no mature oöcytes; (2) ca. 25% of oöcytes mature; (3) ca. 50% of oöcytes mature; (4) >75% of oöcytes mature, >30 mature oöcytes; and (5) >75% of oöcytes mature, <30 mature oöcytes. At 26.7°C, 96.6% of the adult females in age classes 1, 2, 3, 4, and 5 were within the age intervals of ca. 0 to 2, 2 to 4, 4 to 6, 6 to 8, and 8 to 10 days of adult age, respectively. Fat body depletion in the abdomen was used to construct three male age classes: (1) much fat body material, ca. 0 to 25% depleted; (2) moderate fat body material, ca. 50% depleted; and (3) little fat body material, >75% depleted. At 26.7°C, 90.9% of the adult males in age classes 1, 2, and 3 were within the age intervals of ca. 0 to 4, 6 to 8, and 8 to 10 days of adult age, respectively. These physiologically based, female and male classification systems appear suitable for determining chronological age structure of feral populations.

Development and endocrine regulation of mitochondrial cytochrome biosynthesis in the insect fat body: δ-Aminolevulinic acid synthase

Aminolevulinic acid (ALA) synthase activity was measured in fat body mitochondria from adult male Blaberus discoidalis cockroaches. The enzyme reached its maximum activity at 4 to 6 days of adult age and then dropped to a minimal level which was maintained throughout the remainder of the study period. ALA synthase activity was doubled by allylisopropylacetamide and showed a half-life of about 6 h at 25 °C. Enzyme activity was depressed by long-term allatectomy. However, juvenile hormone administration in vivo did not significantly stimulate the enzyme relative to appropriate controls, and endocrine regulation of fat body ALA synthase remains inconclusive. Hemin inhibited ALA synthase activity, suggesting that fat body heme synthesis could be regulated by end-product inhibition.

Biogenesis of mitochondria: Neuroendocrine effects on the development of respiratory functions in fat body mitochondria of the cockroach, Blaberus discoidalis

Fat body mitochondria from male Blaberus discoidalis cockroaches underwent a hormone-independent respiratory development during the first 5 days of adult life followed by a neurohormone-dependent development during the next 5 days. Increases of two- to threefold were shown for oxygen uptake and for succinate-cytochrome c reductase and cytochrome c oxidase activities during this period. Also, an increased capacity for respiratory control by ADP was evident. No further respiratory changes occurred between 10 and 30 days of adult age. Respiratory enzyme activities and respiratory control failed to develop beyond the 5 day level after disruption of neurosecretory functions by extirpation of the corpora cardiaca. Conversely, daily administration of corpora cardiaca extracts stimulated precocious 10 day levels of respiration by 5 days of adult age. Uncoupling with 2,4-DNP indicated electron transport as the rate-limiting process of respiratory activity. Total incorporation of 14Camino acids into fat body mitochondria increased twofold during the first 5 days of adult life. This level of amino acid incorporation was maintained thereafter and corpora cardiaca removal had no effect. The fat body of Blaberus appears useful for studies on the hormonal regulation of mitochondrial development in higher eucaryotic animals.