Depressed Growth Rate Research Articles

The Valence-Dependent Activity of Colloidal Molecules as Ice Recrystallization Inhibitors.

Inspired by advances in cryopreservation techniques, which are essential for modern biomedical applications, there is a special interest in the ice recrystallization inhibition (IRI) of the antifreeze protein (AFPs) mimics. There are in-depth studies on synthetic materials mimicking AFPs, from simple molecular structure levels to complex self-assemblies. Herein, we report the valence-dependent IRI activity of colloidal organic molecules (CMs). The CMs were prepared through polymerization-induced particle-assembly (PIPA) of the ABC-type triblock terpolymer of poly(acryloxyethyl trimethylammonium chloride)-b-poly(benzyl acrylate)-b-poly(diacetone acrylamide) (PATAC-b-PBzA-b-PDAAM) at high monomer conversions. Stabilized by the cationic block of PATAC, the strong intermolecular H-bonding and incompatibility of the PDAAM block with PBzA contributed to the in situ formation of Janus particles (AX1) beyond the initial spherical seed particles (AX0), as well as the high valency clusters of linear AX2 and trigonal AX3. Their distribution was controlled mainly by the polymerization degrees (DPs) of PATAC and PDAAM blocks. IRI activity results of the CMs suggest that the higher fraction of AX1 results in the better IRI activity. Increasing the fraction of AX1 from 27% to 65% led to a decrease of the mean grain size from 39.8% to 10.9% and a depressed growth rate of ice crystals by 58%. Moreover, by replacing the PDAAM block with the temperature-responsive one of poly(N-isopropylacrylamide) (PNIPAM), temperature-adjustable IRI activity was observed, which is well related to the reversible transition of AX0 to AX1, providing a new idea for the molecular design of amphiphilic polymer nanoparticle-based IRI activity materials.

The impact of ascidian biofouling on the farmed Mediterranean mussel Mytilus galloprovincialis physiology and welfare, revealed by stress biomarkers

In biofouling communities, ascidians are among the most damaging species, presenting severe threats, such as depressed growth rates and decreased chances of lower survival, to shellfish aquaculture. However, little is known concerning the fouled shellfish physiology. In an effort to obtain information for the magnitude of stress caused by ascidians to farmed Mytilus galloprovincialis, five seasonal samplings took place in a mussel aquaculture farm suffering from ascidian biofoulants, in Vistonicos Bay, Greece. The dominant ascidian species were recorded and several stress biomarkers, including Hsp gene expression at both mRNA and protein levels, as well as MAPKs levels, and enzymatic activities of intermediate metabolism were examined. Almost all investigated biomarkers revealed elevated stress levels in fouled mussels compared to non-fouled. This enhanced physiological stress seems to be season-independent and can be attributed to the oxidative stress and/or feed deprivation caused by ascidian biofouling, thus illuminating the biological impact of this phenomenon.

Slower growth of farmed eels stocked into rivers with higher wild eel density.

Farmed anguillid eels are frequently stocked into natural fresh waters to enhance eel resources, but little is known about what happens to these eels or their interactions with wild eels after stocking. A recent study observed a depressed survival and growth rate of farmed Japanese eels when they were reared with wild eels, which indicated that wild eels might interfere with the survival and growth of farmed-and-stocked eels through intraspecific competition. To contribute to improving eel stocking efficiency, the growth of farmed-and-stocked Japanese eels was compared among four rivers with different wild eel densities using mark-and-recapture studies. Based on the 2-year recapture survey after stocking, it was found that the density of the farmed-and-stocked eels was not significantly different among rivers. The daily growth rates of farmed-and-stocked eels in the rivers with lower wild eel density were significantly higher than those of the eels stocked into the rivers with higher wild eel density. The farmed-and-stocked eels moved significantly greater distances downstream than wild eels that showed sedentary behaviour. This and previous studies indicate that significant questions remain about the effectiveness of stocking farmed eels into water bodies where naturally recruited wild eels are present.

Credit and economic regeneration after the financial crisis in CESEE

The global financial crisis terminated lending growth rates in CESEE countries, and seven years after financial global crisis, bank credit still continues with depression rate. Demand and supply for bank credit are contracted, as a results of various factors. The paper tries to find the level of credit contraction and factors that may have affected it, as well as policy action which are being taken to improve bank performance. Economic activity on the other hand, despite the depressed credit growth rates seem to show a trend of regeneration. This phenomenon of increasing economic activity without the support of the loan seems is happening in this post-crisis period in CESEE countries, although we must say that it remains undesirable phenomenon.

Distribution, genetic heterogeneity, and antimicrobial susceptibility of Brachyspira pilosicoli in Swiss pig herds

Brachyspira (B.) pilosicoli is a bacterium causing porcine intestinal spirochaetosis, a disease characterized by diarrhoea and depressed growth rates especially in nursery and fattening pigs. Knowledge of the epidemiology and antimicrobial susceptibility of this pathogen is limited. Therefore, the aim of this study was to analyse the distribution, genetic heterogeneity, and antimicrobial susceptibility of B. pilosicoli field isolates from Swiss pig farms. Faecal swabs of 693 animals originating from 156 herds were analysed for the presence of Brachyspira spp. using culture and polymerase chain reaction identification. Further characterisation was performed using multilocus sequence typing (MLST) and broth dilution antimicrobial susceptibility testing. With 52.6% positive herds, B. pilosicoli could be frequently isolated from herds with animals suffering from diarrhoea. In herds with animals without clinical signs of diarrhoea, detection was significantly less frequent with only 10.5% positive herds (p 0.001). Among 80 isolates used for typing, genetic heterogeneity was observed with 44 different sequence types (ST) which often differed from herd to herd. No predominant ST was observed. More than 73.0% of the 41 B. pilosicoli isolates analysed, showed minimal inhibitory concentration values above the wild type cut-off values for lincomycin, tylvalosin and/ or tylosin. For tiamulin, valnemulin and doxycycline, this was the case in 48.8%, 43.9% and 36.6%, respectively. In conclusion, a diverse population of B. pilosicoli exhibited decreased susceptibility to antimicrobials used against Brachyspira infections. Monitoring of resistance in Brachyspira spp. is highly recommended to support targeted use of antimicrobials in pigs.

Etiology of Colitis-Complex Diarrhea in Growing Pigs: A Review

Simple SummaryDiarrhea in growing pigs is a challenge for the pig industry since it is associated with reduced animal welfare, retarded growth, increased feed conversion ratio, and is often treated with antibiotics. One of the major causes of diarrhea in the growing period is large intestinal inflammation, often referred to as colitis. The exact causes of colitis-complex diarrhea are still to be understood, but dietary factors and/or pathogens have been recognized as the major factors in developing colitis-complex diarrhea. In this review, a thorough picture of pathogens, dietary factors, and a number of possible biomarkers related to colitis-complex diarrhea is presented.Colitis-complex diarrhea (CCD) in pigs can be defined as a type of diarrhea, which is associated with colonic inflammation and disrupted colonic gut barrier functionality in growing pigs (4–16 weeks post-weaning). It is a challenge for the pig industry as it is associated with the high use of antibiotics, reduced animal welfare, and depressed growth rate. The exact etiology of CCD is still unclear; however, pathogens including Brachyspira (B.) hyodysenteriae, B. pilosicoli, and swine whipworms such as Trichuris (T.) suis have been involved in specific colitis (SC). In the absence of specific pathogens, dietary factors, such as high levels of protein, pelleted feedstuffs, and lack of sufficient antioxidants, can result in non-specific colitis (NSC). On the other hand, supplement of polyunsaturated fatty acids (PUFA) and polyphenols, sufficient supply of essential amino acids (e.g., threonine, cysteine, and proline), short-chain fatty acids (SCFA; especially butyrate), and resistant starch have shown to confer preventing/ameliorating effects on CCD. Different putative biomarkers associated with CCD have been presented. It is anticipated that a comprehensive picture of the possible causes of CCD and potential dietary interventions could cast light on the direction of future studies aimed at developing preventive and curative strategies against CCD in growing pigs.

Abstract 1688: Lymphatic delivery of virus-like particles in combination with mono- or combinational checkpoint blockade immunotherapy enhances tumor response and antigen-specific functionality of T cells in tumor microenvironment

Abstract T cell priming against tumor antigens (tAgs) is essential for checkpoint blockade immunotherapy (CBI). When these therapies are delivered systemically (intravenously, i.v), Ag-indiscriminate T cell priming and proliferation can occur, reducing anti-tumor immunity and increasing the potential for immune related adverse events (irAEs). Herein, we use lymphatic delivery (intradermally, i.d) of αCTLA4 combined with virus-like particles (VLPs) to increase tAg functionality of tumor infiltrating lymphocytes (TILs) in mono- and combinational CBI regimens. Beginning at 7 days post implant (p.i) of B16F10 in the right hindlimb, αCTLA4 alone or in combination with αPD1 was administered i.v or i.d at the right base of the tail to reach popliteal or inguinal tumor draining lymph nodes (tdLNs) at intervals of 2 days for three doses. Near-infrared fluorescence imaging confirmed delivery to tdLNs. VLP presenting Melan-A as tAg was administered i.d at days 7 and 14 p.i. Tumor volumes were measured daily and at sacrifice on day 17 p.i. Animals with exponential tumor growth at time of sacrifice were deemed to be non-responders. PBMCs and tumor tissues were collected and analyzed via flow cytometry for CD4+ and CD8+ cells as well as for functionality to tAg as reflected from INFγ and TNFα production. αCTLA4 delivered i.d (N=5) exhibited significantly (p<0.05) reduced growth rates compared to when αCTLA4 was delivered i.v (N=5). VLP administration further depressed growth rates (N=20, p<0.05). Additionally, dosing of αCTLA4 i.d and VLP i.d resulted in 50% more responders than when αCTLA4 was dosed i.v. Dose of αCTLA4, αPD1, and VLP i.d further reduced tumor growth compared to animals receiving VLP i.d and combinational CBI i.v (N=20, p<0.05). Finally, there were no responders in animals receiving αCTLA4 i.v alone (N=5) or in combination with αPD1 i.v and VLP i.d, highlighting the importance of lymphatic delivery on immune priming. We found increased tAg specific CD8+ TNFα+ TILs when αCTLA4 was administered i.d than i.v in both mono- and combinational CBIs (p<0.05). TAg specific CD8+TNFα+ T-cells in PBMCs were also higher in responders than non-responders who received αCTLA4 i.d. In non-responders of αCTLA4 monotherapy, IFNγ production was higher in CD4+ and CD8+ TILs than in responders. Taken together these data support the hypothesis that regional lymphatic delivery of αCTLA4 alone or in combination with αPD1 in tdLNs that are recipient of tAgs enhances anti-tumor immunity. Lymphatic delivery of αCTLA4 and VLP induces robust antitumor activity. Future work involves evaluating how manipulation of tdLNs and non-tdLNs can shape the immune status of the tumor microenvironment. Whether irAEs can be alleviated with lymphatic delivery remains to be evaluated in our pre-clinical models. Supported by CPRIT RP19009. Citation Format: Carolina Mantilla Rojas, Dongliang Liu, Fred Christian Velasquez, Janelle Morton, Wen-Jen Hwu, Qizhi Yao, Eva Sevick-Muraca. Lymphatic delivery of virus-like particles in combination with mono- or combinational checkpoint blockade immunotherapy enhances tumor response and antigen-specific functionality of T cells in tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1688.

Genome-wide association analysis of adaptation to oxygen stress in Nile tilapia (Oreochromis niloticus)

BackgroundTilapia is one of the most abundant species in aquaculture. Hypoxia is known to depress growth rate, but the genetic mechanism by which this occurs is unknown. In this study, two groups consisting of 3140 fish that were raised in either aerated (normoxia) or non-aerated pond (nocturnal hypoxia). During grow out, fish were sampled five times to determine individual body weight (BW) gains. We applied a genome-wide association study to identify SNPs and genes associated with the hypoxic and normoxic environments in the 16th generation of a Genetically Improved Farmed Tilapia population.ResultsIn the hypoxic environment, 36 SNPs associated with at least one of the five body weight measurements (BW1 till BW5), of which six, located between 19.48 Mb and 21.04 Mb on Linkage group (LG) 8, were significant for body weight in the early growth stage (BW1 to BW2). Further significant associations were found for BW in the later growth stage (BW3 to BW5), located on LG1 and LG8. Analysis of genes within the candidate genomic region suggested that MAPK and VEGF signalling were significantly involved in the later growth stage under the hypoxic environment. Well-known hypoxia-regulated genes such as igf1rb, rora, efna3 and aurk were also associated with growth in the later stage in the hypoxic environment. Conversely, 13 linkage groups containing 29 unique significant and suggestive SNPs were found across the whole growth period under the normoxic environment. A meta-analysis showed that 33 SNPs were significantly associated with BW across the two environments, indicating a shared effect independent of hypoxic or normoxic environment. Functional pathways were involved in nervous system development and organ growth in the early stage, and oocyte maturation in the later stage.ConclusionsThere are clear genotype-growth associations in both normoxic and hypoxic environments, although genome architecture involved changed over the growing period, indicating a transition in metabolism along the way. The involvement of pathways important in hypoxia especially at the later growth stage indicates a genotype-by-environment interaction, in which MAPK and VEGF signalling are important components.

Growth and carcas characteristics of broilers fed alkali processed soybeans

An eight-week feeding tial was conducted to investigate the effect of feeding alkali processed soyabeans to broilers. Soyabeans were processed in aqueous solutions of sodium chloride, sodium sesquicarvonate (trona) and alum respectively. The concentration of each of the salts was 3%. The soyabeans, after drying, were used in compounding 3 diffefrent diets. The control (T1) contained roasted soyabeans while diets T2 , T3 and T4 contained NaCl, trona and alum respectively. Broiler feeding lasted for 8 weeks starting from day - old. The results indicated that feeding NaCl processed soyabeans to broilerss significantly (P<0.05) depressed growth rate, feed consumption and body gain. NaCl treated soyabeans produced feed/gain ratio, protein efficiency ratio (PER), carcass and organ proportion comparable to thr control. The growth rate, feed intake and weight gain of NaCl to sufficiently inactive trypsin inhibitors and remove a substsntisl proportion of polyphenols and oligosaccharides in soyabeans. It was concluded that since alkaline salts are cheap and readily available all the year round their use in processing soyabeans should be encourage.

Effect of dietary raw, cooked and toasted mucuna pruriens seeds (velvet bean) on the performance of Finisher broilers

A 5-week feeding trial was conducted to determine the effect of dietary raw, cooked and toasted Mucuna puriens seeds contained 30.3% crude protein. At 10% dietary level, raw and toasted Mucuna puriens seed meals significantly (P<0.05) depressed growth rate of broilers. At 20% dietary level, cooked Mucuna puriensseedmeal also significantly (P<0.05) depressed growth rate of the birds. Feed intake was also significantly (P<0.05) reduced at 20% and 10% dietary levels of cooked and toasted meals, respectively. The feed intake of the group on 10% raw Mucuna diet remained unexpectedly high

PERFORMANCE AND NUTRIENT UTILIZATION OF DIETS CONTAINING RAW, BOILED OR DEHULLED PIGEONPEA SEED MEALS (Cajanusc cajan) FED TO BROILER FINISHERS

One hundred and eighty, 4-week old broilers were used to study the performance of broiler finishers fed diets containing raw, boiled or dehulled pigeonpea seed meals included at levels of 30 and 40% of the diets in a 33 x2 factorially designed experiment. Performance criteria were daily weight gain, feed intake, feed conversion ratio (FCR), protein efficiency ratio (PER), nutrient utilization and final liveweight of the broilers at the end of 8" week. Results showed that dehulled seed meal diet produced broilers with the highest daily weight gain, final liveweight and protein efficiency ratio, lowest feed intake, FCR and daily protein intake. Broilers fed boiled seed meal diet performed significantly better than those fed raw seed meal diet in all measurements. Broilers fed on 30% inclusion level of PPSM gave better results than those on 40% which significantly depressed growth rate, feed conversion efficiency, protein efficiency and increased protein intake. The interaction between processing methods and inclusion levels were not significant. There was a higher nutrient utilization of dehulled and boiled PPSM diets by broilers than the raw seed meal. Increase in the level of inclusion generally decreased protein retention except for the dehulled PPSM diet. It is concluded that a better option is to dehull boiled pigeonpea seeds and include the meal at not more than 30% of the whole ration for broiler finishers.
 

Effects of graded levels of kolanut husk on the performance of cockerels

Eighty black Nera cockerel chicks were randomly alloted to four dietarey treatmants containing 0, 10, 20 and 30% kolanut husk meal (KHM) for twelve weeks. Significant differences (P<0.05) in feed intake, weight gain and feed conversion ratio were observed. Dietary inclusion of KHM depressed (P<0.05) growth rate feed conversion ratio and nutrition uilization of cockerels birds. There were linear reduction (P>0.05) in nitrogen retention and apparent crude fibre digestibility (ACFD) of cockerels birds at each incremental KHM dietary levels. This indicated that KHM could be effeciently utilized by cockerels up to 205 dietary level above which the depression in growth rate occurs.

Interactive Effects of CO2, Temperature, Irradiance, and Nutrient Limitation on the Growth and Physiology of the Marine Diatom Thalassiosira pseudonana (Coscinodiscophyceae)

The marine diatom Thalassiosira pseudonana was grown in continuous culture systems to study the interactive effects of temperature, irradiance, nutrient limitation, and the partial pressure of CO2 (pCO2 ) on its growth and physiological characteristics. The cells were able to grow at all combinations of low and high irradiance (50 and 300μmolphotons·m-2 ·s-1 , respectively, of visible light), low and high pCO2 (400 and 1,000μatm, respectively), nutrient limitation (nitrate-limited and nutrient-replete conditions), and temperatures of 10-32°C. Under nutrient-replete conditions, there was no adverse effect of high pCO2 on growth rates at temperatures of 10-25°C. The response of the cells to high pCO2 was similar at low and high irradiance. At supraoptimal temperatures of 30°C or higher, high pCO2 depressed growth rates at both low and high irradiance. Under nitrate-limited conditions, cells were grown at 38±2.4% of their nutrient-saturated rates at the same temperature, irradiance, and pCO2 . Dark respiration rates consistently removed a higher percentage of production under nitrate-limited versus nutrient-replete conditions. The percentages of production lost to dark respiration were positively correlated with temperature under nitrate-limited conditions, but there was no analogous correlation under nutrient-replete conditions. The results suggest that warmer temperatures and associated more intense thermal stratification of ocean surface waters could lower net photosynthetic rates if the stratification leads to a reduction in the relative growth rates of marine phytoplankton, and at truly supraoptimal temperatures there would likely be a synergistic interaction between the stresses from temperature and high pCO2 (lower pH).

Effects of food deprivation on plasma insulin-like growth factor-1 (Igf1) and Igf binding protein (Igfbp) gene transcription in juvenile cabezon (Scorpaenichthys marmoratus)

The growth hormone (GH)/insulin-like growth factor (Igf) endocrine axis regulates somatic growth in the face of changing environmental conditions. In actinopterygian fishes, food availability is a key modulator of the somatotropic axis, with lower food intake generally depressing liver Igf1 release to diminish growth. Igf1 signaling, however, also involves several distinct IGF binding proteins (Igfbps), and the functional roles of many of these Igfbps in affecting growth during shifting food availability remain uncertain. Here, we tested how complete food deprivation (fasting) affected gene transcription for paralogs of all six types of Igfbps in the liver and fast-twitch skeletal muscle of cabezon (Scorpaenichthys marmoratus), a nearshore marine fish important for recreational fisheries in the eastern North Pacific Ocean. Juvenile cabezon were maintained as either fed (6% mass food⋅g fish wet mass−1⋅d−1) or fasted for 14 d. Fasted fish exhibited a lower body condition (K), a depressed mass-specific growth rate (SGR), and reduced plasma concentrations of Igf1. In the liver, fasting reduced the relative abundance of gene transcripts encoding Igfbps igfbp2a and igfbp2b, while significantly elevating mRNA levels for igfbp1a, igfbp1b, igfbp3b, and igfbp4. Fasting also reduced hepatic mRNA levels of GH receptor-1 (ghr1) – but not GH receptor-2 (ghr2) – supporting the idea that changes in liver sensitivity to GH may underlie the decline in plasma Igf1 during food deprivation. In skeletal muscle, fasting downregulated gene transcripts encoding igf1, igfbp2b, igfbp5b, and igfbp6b, while also upregulating mRNAs for igf2 and ghr2. These data demonstrate isoform-specific regulation of Igfbps in liver and skeletal muscle in cabezon experiencing food deprivation and reinforce the idea that the repertoire of duplicated Igfbp genes that evolved in actinopterygian fishes supports a diverse scope of endocrine and paracrine functions.

Effects of temperature and light on photosynthesis and growth of red alga Pyropia dentata (Bangiales, Rhodophyta) in a conchocelis phase

Pyropia aquaculture industries have grown in a recent year, but information is still lacking regarding cultivation techniques for early life stages. In this study, photosynthetic performance and growth of Pyropia dentata in the conchocelis phase was investigated under various culture conditions. Specifically, we used culture conditions with different temperature (10, 15, and 20 °C), light intensity (20 and 70 μmol photons m−2 s−1), and light type (LEDBlue, LEDRed, LEDBlue+Red, and fluorescent lamp) combinations. Photosynthesis was measured using chlorophyll fluorometry (Mini-PAM) after 3 weeks of acclimation under various experimental conditions. Additionally, image analysis was used to determine growth and estimate the 2-dimensional area of complicated conchocelis structures. Results showed that growth rates significantly increased under higher temperatures (15 and 20 °C), but light intensity did not significantly influence photosynthesis and growth. LEDBlue+Red and LEDBlue treatments had higher growth rates and photosynthetic efficiency than LEDRed and fluorescent lamp treatments after the 3-week acclimation period. However, higher photochemical capacity (photosynthesis) was clearly observed in the low temperature condition; thus, depressed growth rates in the low temperature condition are not indicative of physiological senescence of P. dentata conchocelis. Based on these results, we established optimized laboratory cultivation conditions for the conchocelis phase of P. dentata. Specifically, we found that this species requires a higher cultivation temperature to ensure optimal growth. Also, mixing red and blue or solitary blue light sources could be an efficient stabilized laboratory cultivation technique.

Osmoregulatory function of betaine in alleviating heat stress in poultry.

This review focuses on the osmoregulatory function of betaine and its effect in terms of alleviating heat stress in poultry. Poultry appear to be particularly sensitive to temperature-associated environmental challenges, especially heat stress. High ambient temperatures are deleterious to productive performance in poultry, including broilers, laying hens, quails and turkeys, resulting in considerable economic losses. Heat stress impairs overall poultry production by decreasing feed intake and negatively affecting intestinal development, leading to reduced nutrient digestibility. Apart from inducing a high mortality rate, heat stress is known to depress growth rate and reduce meat yield in broilers. In layers, lower feed intake impairs ovarian function, leading to decreased feed efficiency, egg production and egg quality. In addition, reduced immune functions, such as thyroid activity and antibody production, are evident in poultry exposed to heat stress. Heat stress increases the production of oxidants, causing oxidative stress and lipid peroxidation of cell membranes. Poultry respond physiologically and behaviourally when encountering the negative effects of heat stress, attempting to return the body to homeostasis. This requires energy at the expense of weight gain or egg production. Due to its zwitterionic structure, betaine has osmoprotective properties that aid in protecting intestinal cell proteins and enzymes from environmental stress, including high ambient temperature, thereby counteracting performance losses. Betaine also exerts an osmoregulatory role in cells, regulating water balance, and this results in more stable tissue metabolism. Inclusion of betaine in the diet may be beneficial for alleviating physical reactions to heat stress, as indicated by increases in nutrient digestibility. In broilers, betaine supplementation increases weight gain and breast muscle yield, while improving feed conversion. In layers, betaine supplementation improves egg production, egg quality traits and immune indices. In conclusion, due to its osmoregulatory functions, betaine plays an important role in alleviating heat stress in poultry.

Habitat Loss and Local Extinction: Linking Population Declines of Eastern Collared Lizards (Crotaphytus collaris) to Habitat Degradation in Ozark Glades

Abstract Habitat loss and degradation are the leading causes of local extinctions, making preservation and restoration of remaining habitat increasingly critical to conserving biodiversity. Mechanisms driving species extinction, however, often begin with habitat loss and seldom are well understood, which greatly limits our ability to mitigate their impacts. The first step in understanding mechanisms that drive local extinction is to identify vital rates affected by habitat degradation. Here we provide a case study of the impact of habitat degradation on individual growth and reproductive rates of Eastern Collared Lizards (Crotaphytus collaris), a species of special concern in the Ozark Mountains. Our data suggest that C. collaris in habitats encroached by dense woody vegetation have reduced age-specific body size, primarily as a result of depressed individual growth rates in their first 2 yr of life. In turn, female C. collaris in habitats with high woody vegetation density have delayed age of maturity (b...

Targeting symbiosis-related insect genes by RNAi in the pea aphid-Buchnera symbiosis

The growth and reproduction of phloem sap-feeding insects requires the sustained function of intracellular bacteria localized in specialized cells known as bacteriocytes, giving the potential to target the bacterial symbiosis as a novel strategy for controlling sap-feeding insect pests. We focused on two genes in the pea aphid Acyrthosiphon pisum, amiD and ldcA1, which were acquired horizontally from bacteria and have the annotated function to degrade immunogenic bacterial peptidoglycan. We hypothesized that AmiD and LdcA1 function to eliminate peptidoglycan fragments released by the bacterial symbiont Buchnera inhabiting the bacteriocytes, thereby protecting the Buchnera from host attack. Consistent with this hypothesis, expression of amiD and ldcA1 was enriched in bacteriocytes and varied significantly with aphid age, conforming to an inverse curvilinear relationship for amiD and negative linear relationship for ldcA1. RNAi against amiD and ldcA1 administered orally to larval pea aphids caused a significant reduction in Buchnera abundance and activity, accompanied by depressed aphid growth rates. For RNAi experiments, the aphids were co-administered with dsRNA against an aphid nuclease nuc1, protecting the dsRNA against non-specific degradation. These experiments demonstrate that selective suppression of insect symbiosis-related gene function can reduce the performance of an insect pest. Phylogenetic analysis identified amiD and ldcA1 in sequenced genomes of other aphid species, and amiD in related groups of phloem-feeding insects, offering the opportunity for specific controls against a range of insect pests.

Influence of Winter Conditions on the Age, Hatch Dates, and Growth of Juvenile Atlantic Menhaden in the Choptank River, Maryland

AbstractSince 1993, the Atlantic Menhaden Brevoortia tyrannus has experienced sustained low juvenile production (recruitment) in the Chesapeake Bay. We hypothesized that factors affecting wintertime larval growth in Atlantic Ocean shelf habitats carry over to juvenile growth and survival within the Chesapeake Bay. The effects of winter thermal conditions on the hatch dates and growth of larval and juvenile Atlantic Menhaden were examined using otolith increment analyses. During 2010–2013, truncated hatch date distributions for Atlantic Menhaden provided evidence of a winter recruitment bottleneck caused by cold temperatures. Hatch dates of surviving juveniles were skewed toward warmer months for years characterized by colder temperatures. Reduced larval growth rates, which were influenced by lower temperature and reduced food availability, carried over to juvenile growth rates for the same individuals. If larvae that are destined for ingress to the Chesapeake Bay predominately originate from early winter hatch, a recruitment bottleneck may occur, caused by either direct larval mortality or depressed larval growth rates owing to sublethal winter temperatures. Depressed larval growth rates, when not lethal, have the potential to carry over as reduced juvenile growth and survival after estuarine ingress.

Effect of gelatin supplementation on growth performance and blood metabolites of broiler chickens fed diets varying in crude protein

An experiment was conducted to investigate the effects of gelatin inclusion on growth performance, blood metabolites and carcass characteristics of broiler chickens fed diets varying in crude protein (CP) concentration in a 42-d study. Four concentrations of gelatin (0, 30, 60, and 90g/kg) and 2 concentrations of CP in the starter (220 and 200g/kg) and grower (195 and 182g/kg) periods were evaluated in a 2×4 factorial arrangement of treatments. Each diet was fed to 5 replicate pens of 15 male broiler chickens (Ross 308) from d 0 to 42. Digestibility coefficients of amino acid (AA) of gelatin were in the range of 0.90–0.95. Gly, Pro, Ala, and Glu were the major AA in gelatin. There were interactions between dietary CP content and gelatin concentration for feed intake (FI; P=0.016), body weight gain (BWG; P<0.001) and feed conversion ratio (FCR; P<0.001) during the starter (d 0–21), grower (d 21–42), and the overall experiment period (d 0–42). In the low CP diets, gelatin inclusion had a greater negative effect on BWG and FCR compared with those fed the normal CP diets over the course of the experiment (gelatin×CP, P<0.001). The contrasts showed that the increase in dietary gelatin content decreased BWG and FI, whereas FCR increased with higher dietary gelatin content from d 0 to 42. The CP×gelatin interactions showed that gelatin addition to the low CP diets increased plasma concentrations of glucose (gelatin×CP, P<0.01) and uric acid (gelatin×CP, P<0.001), and decreased N retention (gelatin×CP, P<0.001) to a greater extent than was the case for the normal CP diets at d 42. The CP×gelatin interactions indicated that gelatin inclusion in the low CP diets decreased carcass yield (gelatin×CP, P<0.01) and abdominal fat (gelatin×CP, P<0.001), and increased heart weight (gelatin×CP, P<0.01) to a greater extent than was the case for the normal CP diets. The present findings showed that gelatin inclusion had a greater negative effect on growth performance and carcass yield in broiler chickens that received the low CP diets compared with those fed the normal CP diet over the course of the study. Also, increasing dietary gelatin content depressed growth rate and N retention.