Norepinephrine transporter heterozygous knockout mice exhibit altered transport and behavior

The norepinephrine (NE) transporter (NET) regulates synaptic NE availability for noradrenergic signaling in the brain and sympathetic nervous system. Although genetic variation leading to a loss of NET expression has been implicated in psychiatric and cardiovascular disorders, complete NET deficiency has not been found in people, limiting the utility of NET knockout mice as a model for genetically driven NET dysfunction. Here, we investigate NET expression in NET heterozygous knockout male mice (NET^+/?), demonstrating that they display an approximately 50% reduction in NET protein levels. Surprisingly, these mice display no significant deficit in NET activity assessed in hippocampal and cortical synaptosomes. We found that this compensation in NET activity was due to enhanced activity of surface‐resident transporters, as opposed to surface recruitment of NET protein or compensation through other transport mechanisms, including serotonin, dopamine or organic cation transporters. We hypothesize that loss of NET protein in the NET^+/? mouse establishes an activated state of existing surface NET proteins. The NET^+/? mice exhibit increased anxiety in the open field and light–dark box and display deficits in reversal learning in the Morris water maze. These data suggest that recovery of near basal activity in NET^+/? mice appears to be insufficient to limit anxiety responses or support cognitive performance that might involve noradrenergic neurotransmission. The NET^+/? mice represent a unique model to study the loss and resultant compensatory changes in NET that may be relevant to behavior and physiology in human NET deficiency disorders .     

Milk composition in free-ranging polar bears (Ursus maritimus) as a model for captive rearing milk formula

The goals of this study were to have an improved understanding of milk composition and to help create a suitable milk formula for cubs raised in captivity. Milk samples were evaluated for fat, fatty acids, carbohydrate, vitamin D(3), 25(OH)D(3), vitamin A (retinol), vitamin E (α-tocopherol), protein, and amino acids. Total lipids in milk did not differ for cubs (mean ± SEM = 26.60 ± 1.88 g/100 ml vs. yearlings 27.80 ± 2.20 g/100 ml). Milk lipids were of 23.6% saturated fatty acid for cubs and 22.4% for yearlings. Milk consumed by cubs and yearlings contained 43.8 and 42.0% mono-unsaturated fatty acids and 23.4 and 21.9% polyunsaturated fatty acids, respectively. Carbohydrate content was higher in milk for cubs (4.60 ± 0.64 g/100 ml) than for yearlings (2.60 ± 0.40 g/100 ml). Vitamin D(3) concentration of milk was 18.40 ± 5.00 ng/ml in early lactation compared with 7.60 ± 2.00 ng/ml for mid-lactation. 25(OH)D(3) was lower in milk consumed by cubs (162.00 ± 6.70 pg/ml) than in milk consumed by yearlings (205.00 ± 45.70 pg/ml). Vitamin A concentrations were 0.06 ± 0.01 and 0.03 ± 0.01 μg/ml for cubs and yearlings, respectively. Vitamin E was higher in milk consumed by cubs (20.16 ± 4.46 μg/ml) than by yearlings (7.30 ± 1.50 μg/ml). Protein content did not differ in milk available to cubs (11.40 ± 0.80 g/100 ml compared with milk for yearlings 11.80 ± 0.40 g/100 ml). Taurine was the most abundant free amino acid at 3,165.90 ± 192.90 nmol/ml (0.04% as fed basis).     

Hypothalamus integrity and appetite regulation in low birth weight rats reared artificially on a high-protein milk formula

High-protein (HP) milk formulas are routinely used in infants born with a low birth weight (LBW) to enhance growth and ensure a better verbal IQ development. Indirect evidence points to a link between an HP intake during early life and the prevalence of obesity in later life. We hypothesized that HP milk supplementation to LBW pups during early postnatal life would impact hypothalamic appetite neuronal pathways development with consequences, at adulthood, on energy homeostasis regulation. Rat pups born with a LBW were equipped with gastrostomy tubes on the fifth day of life. They received a milk formula with either normal protein (NP, 8.7 g protein/dl) or high protein content (HP; 13.0 g protein/dl) and were subsequently weaned to a standard, solid diet at postnatal day 21. Rats that had been fed HP content milk gained more weight at adulthood associated with an increase of plasma insulin, leptin and triglycerides concentrations compared to NP rats. Screening performed on hypothalamus in development from the two groups of rats identified higher gene expression for cell proliferation and neurotrophin markers in HP rats. Despite these molecular differences, appetite neuronal projections emanating from the arcuate nucleus did not differ between the groups. Concerning feeding behavior at adulthood, rats that had been fed HP or NP milk exhibited differences in the satiety period, resting postprandial duration and nocturnal meal pattern. The consequences of HP milk supplementation after LBW will be discussed in regard to neural development and metabolic anomalies.     

The effect of mating behaviour on progeny sex ratio of Mastrus ridens (Hymenoptera: Ichneumonidae), a biological control agent of codling moth

Mastrus ridens (Horstmann) (Hymenoptera: Ichneumonidae) was imported into quarantine as a potential biocontrol agent for codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae). Mating behaviour of the parasitoid and its effect on progeny sex ratio (as a proportion of males) were studied to help sustain the laboratory culture. Both females and males were reproductively active soon after emergence. Unmated females produced only male progeny, confirming males developed from unfertilized eggs. The proportion of males in a progeny was independent of the copulation period (24–40 s) of the parents. The progeny sex ratios from three parent ratios (f:m 2:1, 1:1 and 1:2) were not significantly different. Females effectively mated only once but males mated frequently in their lifetime. The progeny sex ratios from single females with a known single mating and possible multiple matings (through exposure to two males for 18 days) were not significantly different. However, when males copulated with five virgin females in sequence over a 2 h period, the fifth female produced more males than the preceding four, presumably due to sperm depletion. Results of this study provide data on progeny sex allocation of M. ridens that help to prevent the development of a male-biased sex ratio that could threaten the maintenance of the culture over time.     

Structural basis of fluorescence quenching in caspase activatable‐GFP

Apoptosis is critical for organismal homeostasis and a wide variety of diseases. Caspases are the ultimate executors of the apoptotic programmed cell death pathway. As caspases play such a central role in apoptosis, there is significant demand for technologies to monitor caspase function. We recently developed a caspase activatable‐GFP (CA‐GFP) reporter. CA‐GFP is unique due to its “dark” state, where chromophore maturation of the GFP is inhibited by the presence of a C‐terminal peptide. Here we show that chromophore maturation is prevented because CA‐GFP does not fold into the robust β‐barrel of GFP until the peptide has been cleaved by active caspase. Both CA‐GFP and GFP_1‐10, a split form of GFP lacking the 11th strand, have similar secondary structure, different from mature GFP. A similar susceptibility to proteolytic digestion indicates that this shared structure is not the robust, fully formed GFP β‐barrel. We have developed a model that suggests that as CA‐GFP is translated in vivo it follows the same folding path as wild‐type GFP; however, the presence of the appended peptide does not allow CA‐GFP to form the barrel of the fully matured GFP. CA‐GFP is therefore held in a “pro‐folding” intermediate state until the peptide is released, allowing it to continue folding into the mature barrel geometry. This new understanding of the structural basis of the dark state of the CA‐GFP reporter will enable manipulation of this mechanism in the development of reporter systems for any number of cellular processes involving proteases and potentially other enzymes.     

Carbon dioxide diffusion across stomata and mesophyll and photo-biochemical processes as affected by growth CO2 and phosphorus nutrition in cotton

Nutrients such as phosphorus may exert a major control over plant response to rising atmospheric carbon dioxide concentration (CO₂), which is projected to double by the end of the 21st century. Elevated CO₂ may overcome the diffusional limitations to photosynthesis posed by stomata and mesophyll and alter the photo-biochemical limitations resulting from phosphorus deficiency. To evaluate these ideas, cotton (Gossypium hirsutum) was grown in controlled environment growth chambers with three levels of phosphate (Pi) supply (0.2, 0.05 and 0.01 mM) and two levels of CO₂ concentration (ambient 400 and elevated 800 μmol mol⁻¹) under optimum temperature and irrigation. Phosphate deficiency drastically inhibited photosynthetic characteristics and decreased cotton growth for both CO₂ treatments. Under Pi stress, an apparent limitation to the photosynthetic potential was evident by CO₂ diffusion through stomata and mesophyll, impairment of photosystem functioning and inhibition of biochemical process including the carboxylation efficiency of ribulose-1,5-bisphosphate carboxylase/oxyganase and the rate of ribulose-1,5-bisphosphate regeneration. The diffusional limitation posed by mesophyll was up to 58% greater than the limitation due to stomatal conductance (g_s) under Pi stress. As expected, elevated CO₂ reduced these diffusional limitations to photosynthesis across Pi levels; however, it failed to reduce the photo-biochemical limitations to photosynthesis in phosphorus deficient plants. Acclimation/down regulation of photosynthetic capacity was evident under elevated CO₂ across Pi treatments. Despite a decrease in phosphorus, nitrogen and chlorophyll concentrations in leaf tissue and reduced stomatal conductance at elevated CO₂, the rate of photosynthesis per unit leaf area when measured at the growth CO₂ concentration tended to be higher for all except the lowest Pi treatment. Nevertheless, plant biomass increased at elevated CO₂ across Pi nutrition with taller plants, increased leaf number and larger leaf area.     

Rearing larval stages of Hippodamia variegata Goeze (Col.: Coccinellidae) on artificial diet

The ladybird Hippodamia variegata Goeze is a widespread species found in many parts of the world. It is an efficient predator which feeds on a wide range of pests, specially aphids and other sap feeders. Mass rearing of this predator, in order to use in biological control programmes, entails a great deal of difficulties, among which are the aspects associated with nutrition. Applying artificial diets is of a great importance in mass rearing of biological control agents. We investigated the use of 15 artificial diets that included three separated experiments, in order to rear larval stages of this ladybird. The survival rate and developmental time were assessed on each treatment. The survival rate of the larvae on best diet was 53.30, 93.33, and 93.33% in different experiments. The developmental time in the experiment 1, 2 and 3 for the larva fed on the Aphis fabae was 15.59, 15.51 and 15.94, respectively, but when nourished by the best artificial diets, this factor was 26.59, 26.60 and 20.59, respectively. Developmental time for the larvae fed on A. fabae was significantly shorter than developmental time of larvae on artificial diets. Our results showed that artificial diets have the capacity to support the larval development to adulthood.     

Early postnatal development of electrophysiological and histological properties of sensory sural nerves in male rats that were maternally deprived and artificially reared: Role of tactile stimulation

Early adverse experiences disrupt brain development and behavior, but little is known about how such experiences impact on the development of the peripheral nervous system. Recently, we found alterations in the electrophysiological and histological characteristics of the sensory sural (SU) nerve in maternally deprived, artificially reared (AR) adult male rats, as compared with maternally reared (MR) control rats. In the present study, our aim was to characterize the ontogeny of these alterations. Thus, male pups of four postnatal days (PND) were (1) AR group, (2) AR and received daily tactile stimulation to the body and anogenital region (AR‐Tactile group); or (3) reared by their mother (MR group). At PND 7, 14, or 21, electrophysiological properties and histological characteristics of the SU nerves were assessed. At PND 7, the electrophysiological properties and most histological parameters of the SU nerve did not differ among MR, AR, and AR‐Tactile groups. By contrast, at PND 14 and/or 21, the SU nerve of AR rats showed a lower CAP amplitude and area, and a significant reduction in myelin area and myelin thickness, which were accompanied by a reduction in axon area (day 21 only) compared to the nerves of MR rats. Tactile stimulation (AR‐Tactile group) partially prevented most of these alterations. These results suggest that sensory cues from the mother and/or littermates during the first 7–14 PND are relevant for the proper development and function of the adult SU nerve. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 351–362, 2018     

Reproduction and resource utilization of the ambrosia beetle,Xylosandrus mutilatus, in field and experimental populations

The reproduction process of the ambrosia beetle,Xylosandrus mutilatus (Blandford) (Coleoptera: Scolytidae), was examined by successive censuses of field populations and by artificial rearing experiments. The reproductive strategy is discussed in relation to utilization of fungal resources, the amount of which was evaluated by total gallery length (main gallery and side galleries) for the field populations or fungal area in the laboratory. Fecundity of mother adults increased with the expansion of gallery systems for cultivating their associated fungi. The number of offspring also depended on the amount of fungal resource, whereas the variation of female body size within a brood was not affected by the fungal amount. The body size apparently declined with delay in larval feeding period expressed as the order of pupation and eclosion in the field and with decreasing fungal area per larva in the laboratory. These results suggested that the combination of resource-dependent oviposition by a mother beetle and dominant resource utilization by earlier-hatched individuals in a brood can contribute to the efficient production of larger females when resources are limited.