High Temperature Regimens Research Articles

Egg hatching success is influenced by the time of thermal stress in four hard tick species.

Ticks are blood-feeding arthropods responsible for the transmission of disease-causing pathogens to a wide range of vertebrate hosts, including livestock and humans. Tick-borne diseases have been implicated in significant economic losses to livestock production, and this threat will increase as these obligate parasites widen their geographical ranges. Similar to other ectotherms, thermal stress due to changing global temperatures has been shown to influence tick survival and distribution. However, studies on the influence of extreme temperatures in ticks have focused on advanced, mobile stages, ignoring immobile stages that cannot move to more favorable microhabitats. In this study, low- and high-temperature regimens were assessed in relation to egg viability for hard tick species-Amblyomma maculatum (Gulf Coast tick), Ixodes scapularis (black-legged tick), Dermacentor variabilis (American dog tick), and Rhipicephalus sanguineus (Brown dog tick). Tick eggs exposed early in development (freshly laid during early embryo development) were significantly more susceptible to thermal stress when compared with those exposed later in development (late embryo development denoted by a fecal spot). Based on our studies, differences in egg hatching success among treatments were greater than in hatching success when comparing species. Lastly, there was evidence of extreme thermal exposure significantly altering the hatching times of tick eggs for specific treatments. These results provide insights into the critical period for tick egg viability in relation to thermal exposure and tick survival associated with stress and climate change.

Thermal response of active Si in press-fit rectifier diodes by confocal Raman microscopy: Influence of diode design and technology

Overheating resulting from the circulation of high electric currents (in the order of tens of amperes) that some electronic devices undergo when they are in operation, can induce structural modifications such as mechanical stresses that could reduce their lifetime. In order to optimize their performance, understanding the phenomenology that takes place in devices at high-temperature regimen induced under operating conditions is fundamental. In this work, the thermal behavior of the Si-based semiconductor part of several press-fit rectifier diodes with different design and technology (Schottky, Metal Oxide Semiconductor and PN junction) has been studied by Confocal Raman Microscopy. The experiments have been performed on two specific functional parts of the active Si chip (i.e., near and far from the Si/electrode interface), discerning non-thermal effects such as stress and doping from the purely thermal ones with a specific analysis procedure of the Si T2g Raman active mode. This methodology enables an advance, non-destructive and located characterization of the thermal response of the diodes, which will help to optimize the performance of electronic devices and extend their useful life and reliability by avoiding or, at least, minimizing the damage caused by the temperature excess.

High Temperature Induced Anthocyanin Inhibition and Active Degradation in Malus profusion.

The red fleshed fruits of Malus profusion represent gradual color loss during high temperature in summer, potentially due to active degradation of anthocyanin. The objective of this study was to examine both physiological and molecular evidence of anthocyanin degradation. Malus crabapple fruits were exposed to either room temperature (RT = 18 ± 2°C: 25 ± 2°C) or high temperature (HT = 33 ± 2°C: 25 ± 2°C) regimens (12 h: 12 h) under hypoxic (2%) or normoxic (21%) oxygen levels. The results showed that the concentration of cyanidin 3-galactoside (cy-3-gal) was dramatically reduced following HT treatments due to a significant down-regulation of anthocyanin biosynthetic genes (MpCHS, MpDFR, MpLDOX, MpUFGT, and MpMYB10). Among other repressor MYBs, MpMYB15 expression was high following HT treatment of the fruit. HT led to the generation of a substantial concentration of H2O2 due to enhanced activities of superoxide dismutase (SOD), methane dicarboxylic aldehyde (MDA) content and cell sap pH value. Similarly, transcript levels of MpVHA-B1 and MpVHA-B2 were reduced which are involved in the vacuolar transportation of anthocyanin. The enzymatic degradation of anthocyanin was eventually enhanced coupled with the oxidative activities of peroxidase (POD) and H2O2. Conversely, the RT treatments potentially enhanced anthocyanin content by stabilizing physiological attributes (such as MDA, H2O2, and pH, among others) and sustaining sufficient biosynthetic gene expression levels. Quantitative real-time PCR analysis indicated that the transcription of MpPOD1, MpPOD8 and MpPOD9 genes in fruit tissues was up-regulated due to HT treatment and that hypoxic conditions seems more compatible with the responsible POD isoenzymes involved in active anthocyanin degradation. The results of the current study could be useful for understanding as well as elucidating the physiological phenomenon and molecular signaling cascade underlying active anthocyanin degradation in Malus crops.

Comparative proteomic analysis of the effect of temperature and fertilizer on gliadin and glutenin accumulation in the developing endosperm and flour from Triticum aestivum L. cv. Butte 86

BackgroundFlour quality is largely determined by the gluten proteins, a complex mixture of proteins consisting of high molecular weight-glutenin subunits (HMW-GS), low molecular weight-glutenin subunits (LMW-GS), and α-, γ-, and ω-gliadins. Detailed proteomic analyses of the effects of fertilizer and high temperature on individual gliadin and glutenin protein levels are needed to determine how these environmental factors influence flour quality.ResultsWheat plants (Triticum aestivum L. cv. Butte 86) were grown in greenhouses under moderate and high temperature regimens with and without post-anthesis fertilizer. Quantitative two-dimensional gel electrophoresis was used to construct accumulation profiles in developing endosperm for the entire complement of gluten proteins identified previously by tandem mass spectrometry. Amounts of individual gliadins and glutenins were also determined in flour produced under each of the regimens. Under all environmental regimens, most HMW-GS, LMW-GS, γ- and ω-gliadins accumulated rapidly during early stages of grain development and leveled off during middle stages of development. A subset of LMW-GS showed a second distinct profile, accumulating throughout development, while α-gliadins showed a variety of accumulation profiles. In flour, fourteen distinct gluten proteins responded similarly to fertilizer, high temperature, and high temperature plus fertilizer. The majority of HMW-GS and ω-gliadins and some α-gliadins increased while two LMW-GS and a minor γ-gliadin decreased. Fertilizer did not influence gluten protein accumulation under high temperature conditions. Additionally, the effects of fertilizer and high temperature were not additive; very few changes were observed when plants that received fertilizer were subjected to high temperature.ConclusionsAlthough post-anthesis temperature and fertilizer have very different effects on grain development and yield, the two treatments elicit surprisingly similar effects on the accumulation of gluten proteins. The similarity of the responses to the different treatments is likely due to source-sink activities of nitrogen reserves in the wheat plant. Because each protein that showed a response in this study is linked to a gene sequence, the work sets the stage for transgenic studies that will better elucidate the roles of specific proteins in flour quality and in the response to the environment.

The wheat chloroplastic small heat shock protein (sHSP26) is involved in seed maturation and germination and imparts tolerance to heat stress

The nuclear-encoded chloroplast small heat shock proteins (sHSPs) are present in all plant species from algae to angiosperms. Expression analysis shows that the wheat chloroplastic sHSP (HSP26) is highly inducible by heat stress in almost all the vegetative and generative tissues and is also expressed constitutively in certain developmental growth stages. We characterize wheat chloroplastic sHSP 26 through transgenic approach using Arabidopsis and report cloning of the promoter and its characterization. Transgenic Arabidopsis plants were substantially tolerant under continuous high temperature regimen than wild-type plants, as measured by photosystem II (PSII) activity, accumulation of more photosynthetic pigments, higher biomass and seed yield. Transgenic plants produced bold seeds under high temperature, having higher germination potential than the wild-type plants. Further, antisense Arabidopsis plants showed negligible tolerance even for non-lethal heat shock, impaired in basal thermo-tolerance, and accumulated less biomass and seed yield under normal growth conditions. Promoter analysis revealed the presence of several heat and other abiotic stress responsive cis-acting elements along with developmental stage and tissue-specific elements. Analysis of promoter through GUS reporter system in both transgenic rice and Arabidopsis further confirms the role of chloroplastic sHsp26 in heat and other abiotic stresses as well as during seed maturation and germination. Genome-wide expression analysis of overexpression Arabidopsis plants revealed that the transcriptome remained unchanged in the transgenic plants and the tolerance was due to the overexpression of chloroplastic heat shock protein (HSP) only.

Effect of high temperature on albumin and globulin accumulation in the endosperm proteome of the developing wheat grain

The accumulation of KCl-soluble/methanol-insoluble albumins and globulins was investigated in the endosperm of developing wheat ( Triticum aestivum, L. cv. Butte 86) grain produced under a moderate (24 °C/17 °C, day/night) or a high temperature regimen (37 °C/28 °C) imposed from 10 or 20 days post-anthesis (dpa) until maturity. Proteins were separated by 2-DE and developmental profiles for nearly 200 proteins were analyzed by hierarchical clustering. Comparison of protein profiles across physiologically equivalent stages of grain fill revealed that high temperature shortened, but did not substantially alter, the developmental program. Accumulation of proteins shifted from those active in biosynthesis and metabolism to those with roles in storage and protection against biotic and abiotic stresses. Few proteins responded transiently when plants were transferred to the high temperature regimens, but levels of a number of proteins were altered during late stages of grain development. Specific protein responses depended on whether the high temperature regimens were initiated early or mid development. Some of the heat responsive proteins have been implicated in gas bubble stabilization in bread dough and others are suspected food allergens.

Expression of globulin-2, a member of the cupin superfamily of proteins with similarity to known food allergens, is increased under high temperature regimens during wheat grain development

Twenty-three expressed sequence tags (ESTs) from the US spring wheat Butte 86 were identified that encode proteins similar to a globulin-2 protein from maize embryos. The ESTs assembled into three contigs, two of which include the entire coding region for the mature protein. The encoded proteins contain two cupin domains and show significant identities with 7S seed proteins from other species that are known or putative food allergens. Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) with primers specific for two of the sequences demonstrated that the globulin-2 genes are expressed late in grain development and that transcript levels increase when grain is produced under high temperature conditions. Transcripts were detected in both whole grain and endosperm, but levels were significantly higher in whole grain and highest in embryo. In wheat flour, at least 17 protein spots that differ in both size and pI were identified as globulin-2 by 2-DE/MS. Seven of the spots increased more than 2-fold in relative proportion when grain was produced under high temperature regimens. The data suggest that both transcriptional and post-translational mechanisms are involved in the response of globulin-2 to high temperatures.

Genes encoding the PR-4 protein wheatwin are developmentally regulated in wheat grains and respond to high temperatures during grainfill

Sequences encoding three wheatwins, including a novel protein not identified previously, were found among expressed sequence tags (ESTs) from grain from the US bread wheat Butte 86 and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was used to detect transcripts specific for two of the wheatwins in a variety of tissues. In the absence of pathogen challenge, wheatwin transcripts were detected in embryo, endosperm, whole grain, awns and glumes as well as in leaves, stems and roots. In both whole grain and endosperm, transcripts accumulated late in development and achieved the highest levels as grain reached maximum dry weight. When high temperature regimens (37/28 °C day/night) were imposed during grain development, the timing of transcript accumulation was compressed and maximum transcript levels were significantly higher than under a moderate 24/17 °C day/night regimen. Accumulation profiles for two wheatwin proteins identified in endosperm by 2-DE/MS were consistent with transcript profiles and flour from grain produced under high temperatures had greater amounts of the two proteins than flour from grain produced under moderate temperatures. The data confirm that wheatwin genes are developmentally regulated in the grain and suggest that wheatwin plays a role in the response of the developing grain to high temperatures in addition to its protective role against fungal pathogens. Enhanced expression of wheatwin genes in grain produced under high temperature conditions may have important implications for wheat flour quality and allergenic potential.

Expression of 9-kDa non-specific lipid transfer protein genes in developing wheat grain is enhanced by high temperatures but not by post-anthesis fertilizer

A survey of EST databases identified 16 9-kDa non-specific lipid transfer proteins (nsLTPs) expressed in developing grain from the US spring wheat Butte 86. Two of the most abundant sequences encoded nsLTPs similar to proteins identified previously by two-dimensional gel electrophoresis/mass spectrometry (2-DE/MS). Quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR) was used to examine the expression of these nsLTPs in developing grain or endosperm produced under controlled temperature and fertilizer regimens. Under a moderate (24 °C/17 °C day/night) temperature regimen, transcripts accumulated late in grain development and achieved highest levels as grain reached maximum dry weight. When high temperature regimens (37 °C/28 °C day/night) were imposed from anthesis or 15 days post-anthesis (DPA) until maturity, maximum transcript levels were as much as 9-fold higher. Post-anthesis fertilizer had relatively small effects on transcript levels. Accumulation profiles for 9-kDa nsLTPs generated by 2-DE were consistent with transcript profiles. The nsLTPs increased 2 to 3.5-fold in amount in endosperm in response to high temperatures but showed little change in response to fertilizer. Flour from grain produced under the high temperature regimens also contained greater amounts of nsLTPs. Increases in the levels of nsLTPs in flour as a result of environmental conditions during grain fill may have important implications for flour quality and allergenic potential.

Differential accumulation of sulfur-rich and sulfur-poor wheat flour proteins is affected by temperature and mineral nutrition during grain development

Hard red spring wheat ( Triticum aestivum cv Butte86) was grown under controlled environmental conditions and grain produced under 24/17 °C, 37/17 °C or 37/28 °C day/night regimens with or without post-anthesis N supplied as NPK. Flour proteins were analyzed and quantified by differential fractionation and RP-HPLC, and endosperm proteins were assessed by two-dimensional gel electrophoresis (2-DE). High temperature or NPK during grain fill increased protein percentage and altered the proportions of S-rich and S-poor proteins. Addition of NPK increased protein accumulation per grain under the 24/17 °C but not the 37/28 °C regimen. However, flour protein composition was similar for grain produced with NPK at 24/17 °C or 37/28 °C. 2-DE of gluten proteins during grain development revealed that NPK or high temperature increased the accumulation rate for S-poor proteins more than for S-rich proteins. Flour S content did not indicate S-deficiency, however, and addition of post-anthesis S had no effect on protein composition. Although, high-protein flour from grain produced under the 37/28 °C regimen with or without NPK had loaf volumes comparable to flour produced at 24/17 °C with NPK, mixing tolerance was decreased by the high temperature regimen.

Protein accumulation and composition in wheat grains: Effects of mineral nutrients and high temperature

Effects of mineral nutrition and temperature on accumulation and composition of protein in wheat grains and on baking quality were studied under controlled environments. Under a moderate temperature regimen of 24 °C days and 17 °C nights (24/17 °C), post-anthesis N:P:K 20:20:20 (NPK) supplied by continuous drip irrigation increased the rate of protein accumulation, doubled flour protein percentage and slightly increased final single kernel weight. In contrast, post-anthesis NPK had almost no effect on rate or duration of protein accumulation or flour protein percentage under a high temperature regimen of 37 °C days and 28 °C nights (37/28 °C). The 37/28 °C regimen shortened and compressed the stages of grain fill, reduced the duration of dry matter accumulation, and reduced single kernel weight by 50%. Rate and duration of protein accumulation in thermal time and total protein per grain at 37/28 °C with or without NPK were similar to that at 24/17 °C in the absence of post-anthesis NPK. Protein percentage was higher for flour from grain produced at 37/28 °C with or without NPK than at 24/17 °C in the presence of post-anthesis NPK. Transcript and protein profiling studies confirmed that the 37/28 °C regimen compressed development without disrupting coordinate synthesis of gliadins and glutenin subunits, although some specific effects of NPK and temperature on relative amounts of individual gliadins and glutenins were observed. Transcript levels for ω-gliadins, α-gliadins and high molecular weight glutenin subunits (HMW-GS) declined at 24/17 °C in the absence of post-anthesis NPK, whereas transcript levels for low molecular weight glutenin subunits (LMW-GS) and γ-gliadins showed little change. Two-dimensional gel electrophoresis (2DE) demonstrated that relative spot volumes for several ω-gliadins, α-gliadins and HMW-GS were lower at 24/17 °C in the absence than in the presence of post-anthesis NPK, whereas the relative spot volume for a major LMW-GS was lower in the presence of NPK. Effects of temperature on relative spot volume were generally smaller than effects of NPK. Compared to the 24/17 °C regimen in the absence of post-anthesis NPK, relative spot volume for some α-gliadins and HMW-GS were higher at 37/28 °C, with or without NPK, and relative spot volume for a major LMW-GS decreased at 37/28 °C. Loaf volume was correlated with flour protein percentage regardless of temperature regimen but mixing tolerance was highest for flour from grain produced under the 24/17 °C regimens with NPK.

Transcript profiles of genes expressed in endosperm tissue are altered by high temperature during wheat grain development

Timing of transcript accumulation for genes involved in a variety of cellular processes was assessed by RT-PCR in endosperm from developing wheat grains grown under moderate (24/17 °C day/night) and high (37/28 °C day/night) temperature regimens. Under moderate temperatures, transcripts for proteins with storage functions were present at all five time points examined between 7 and 34 DPA, while transcripts for proteins involved in signal transduction, protein synthesis and metabolism were most abundant from 7 to 20 DPA. Transcripts for proteins that play roles in defense were present from 14 DPA, about the time that starch accumulation commenced, to 34 DPA. High temperatures advanced and compressed the timing of transcript accumulation during grain development. Comparisons of transcript profiles with the timing of key events in grain development identified genes whose transcripts were accumulated at equivalent stages under the two temperature regimens and might serve as markers for grain development. These comparisons also revealed a number of genes with transcript profiles that were shifted under high temperatures in a manner that was not consistent with developmental events. These genes may be involved in responses to high temperature that are distinct from effects on the timing of developmental processes.

Effect of temperature on expression of genes encoding enzymes for starch biosynthesis in developing wheat endosperm

The effect of high temperature on starch accumulation, starch granule populations, and expression of genes encoding key enzymes for starch biosynthesis was examined during grain development in wheat ( Triticum aestivum L. cv. Butte 86). High temperature applied from anthesis to maturity reduced the duration of starch accumulation. Starch accumulation ceased approximately 6 days earlier for grain produced under a 37/17 °C (day/night) regimen and 21 days earlier under a 37/28 °C (day/night) regimen than for grain produced under a 24/17 °C (day/night) regimen. Compared to the 24/17 °C regimen, starch content was approximately 19% less for mature grain produced under the 37/17 °C regimen and 58% less under the 37/28 °C regimen. Based on relative volume, the smaller type B starch granules were the predominant class in mature grain produced under the 24/17 and 37/17 °C regimens, whereas the larger type A granules were predominant in grain produced under the 37/28 °C regimen. Under the 24/17 °C regimen, steady state transcript levels for ADP-glucose pyrophosphorylase, starch synthases I, II, and III, granule-bound starch synthase, and starch branching enzymes I and II were highest from 12–16 days post-anthesis (dpa). Under the 37/17 °C regimen, steady state levels of these transcripts followed the same temporal pattern, but were substantially lower. Under the 37/28 °C regimen, transcript levels peaked earlier, at 7 dpa. The high temperature regimens reduced the relative levels of transcripts for starch synthase more than the other starch biosynthetic enzymes.

Temperature, Water and Fertilizer Influence the Timing of Key Events During Grain Development in a US Spring Wheat

Controlled environments were used to define the manner in which temperature, water and fertilizer affect the timing of key transition points during grain development and to investigate the effects of combined environmental factors in a US spring wheat (Triticum aestivum (L.)). When plants were subjected to very high temperature regimens (37/17 or 37/28C day/night) during grain development, the times to maximum kernel water content, maximum dry weight and harvest maturity were shorter than in plants maintained under a 24/17C day/night regimen. Starch accumulated at similar rates, but the onset and cessation of starch accumulation occurred earlier. Apoptosis in endosperm tissue also occurred earlier under high temperatures and coincided with physiological maturity. The addition of drought to the 37/17C regimen further shortened the time to maximum water content and dry weight and reduced the duration of starch accumulation, but did not influence the timing of protein accumulation or kernel desiccation. Post-anthesis fertilizer had little effect on time to maximum water content, dry weight, apoptosis, or harvest maturity under any of the temperature regimens and did not influence the timing of starch accumulation. However, both the rate and duration of protein accumulation were reduced when post-anthesis fertilizer was omitted. # 2003 Published by Elsevier Science Ltd

Environmental Conditions During Wheat Grain Development Alter Temporal Regulation of Major Gluten Protein Genes

ABSTRACTThe accumulation of transcripts for the major gluten storage proteins was assessed during grain development in wheat plants (Triticum aestivum L. ‘Butte 86’) grown under seven controlled environments where temperature, water, and fertilizer conditions were varied after anthesis. Transcripts within the α‐, γ‐ and ω‐gliadin, low molecular weight glutenin subunit (LMW‐GS), and high molecular weight glutenin subunit (HMW‐GS) gene families followed similar patterns of accumulation throughout grain development under each environmental regimen. Under moderate daytime temperatures in plants that were well watered and fertilized, transcripts from all gene families were detectable by eight days postanthesis (8 DPA), were present at high levels until ≈34 DPA, and disappeared between 36 and 38 DPA. Under high temperature regimens, transcripts from all gene families appeared slightly earlier, but the time frame of accumulation was shorter. The presence or absence of postanthesis fertilizer did not alter the temporal regulation of the gluten genes under the moderate temperature regimen. However, under the high daytime temperature regimen, transcripts disappeared slightly earlier in kernels from plants that did not receive postanthesis fertilizer. Reverse transcriptase polymerase chain reaction (RT‐PCR) using primer pairs for specific HMW‐GS and LMW‐GS transcripts revealed that individual genes within each family exhibited identical patterns of temporal regulation under different environmental conditions.

Different responses of broilers at low, high, or cyclic moderate-high temperatures to dietary sodium bicarbonate supplementation due to differences in dietary formulation

0es; temperature and NaHCO 3 cant NaHCO 3 ificant overall effect on production parameters but significant NaHCO 3 × temperature and NaHCO 3 × diet interactions were observed for BWG. Sodium bicarbonate improved BWG at constant 31high (25°derate—high (25°—35cyclic moderate—high (25°—35°C) temperature regimens. Dietary formulations using typical Australian feed ingredients and varying in protein sources were used with one diet containing only animal-source protein ingredients (Diet 1) and the other diet containing predominantly plant-source protein ingredients (Diet 2). Feed intake and bodyweight gain (BWG) of broilers exposed to constant high or diurnal cyclic temperature regimens were similar and significantly poorer than those of broilers exposed to low temperatures. Dietary supplementation with NaHCO 3 had no significant overall effect on production parameters but significant NaHCO 3×temperature and NaHCO 3×diet interactions were observed for BWG. Sodium bicarbonate improved BWG at constant 31°C, but not at constant 20NaHCO 3 × temperature and NaHCO 3 cant NaHCO 3 ificant overall effect on production parameters but significant NaHCO 3 × temperature and NaHCO 3 × diet interactions were observed for BWG. Sodium bicarbonate improved BWG at constant 31high (25°derate—high (25°—35cyclic moderate—high (25°—35°C) temperature regimens. Dietary formulations using typical Australian feed ingredients and varying in protein sources were used with one diet containing only animal-source protein ingredients (Diet 1) and the other diet containing predominantly plant-source protein ingredients (Diet 2). Feed intake and bodyweight gain (BWG) of broilers exposed to constant high or diurnal cyclic temperature regimens were similar and significantly poorer than those of broilers exposed to low temperatures. Dietary supplementation with NaHCO 3 had no significant overall effect on production parameters but significant NaHCO 3×temperature and NaHCO 3×diet interactions were observed for BWG. Sodium bicarbonate improved BWG at constant 31°C, but not at constant 20°C, or in the diurnal cyclic temperature regimen. Sodium bicarbonate significantly improved BWG with Diet 2 (plant-source proteins), which contained an arginine : lysine ratio of 1.31 but not with Diet 1 (animal-source proteins), which contained an arginine : lysine ratio of 1.01.

Interaction between ambient temperature and supplementation of synthetic amino acids on performance and carcass parameters in commercial male turkeys

An experiment with male turkeys was conducted to test the hypothesis that turkey production performance responds positively to extra crystalline amino acid supplementation (lysine, methionine, and threonine) when subjected to a high ambient temperature regimen (HT) in the grower period. Two diets were formulated to provide lysine, methionine, and threonine concentrations that either 1) met the breeder recommendations or 2) contained 10% higher lysine and methionine concentrations from 22 to 134 d of age and 10% higher threonine concentration from 22 to 68 d of age. Both diets were fed at two temperatures (15 or 25 C) from 42 d of age onward. At 134 d of age, turkeys on the HT had generally lower BW than those on the low temperature regimen (LT). Up to 68 d of age and from 106 to 134 d of age, feed intake of turkeys on the HT was significantly lower than that of turkeys on the LT. Up to 42 d of age, feed conversion ratio (FCR) of turkeys on the HT were significantly lower than those of turkeys on the LT. Significant treatment interactions were observed from 22 to 41 d of age. Turkeys fed the amino acid-supplemented diets on the LT had significantly reduced FCR, whereas those on the HT did not respond. From 69 to 105 d of age, turkeys on the HT that were fed the supplemented diets had significantly increased FCR, but there were no dietary effects among turkeys on the LT. There were no consistent diet effects on growth performance or carcass yields. Breast meat yields of turkeys on the LT were higher (33.5 vs 32.1%), and drum yields were lower (12.7 vs 13.0%), than those of turkeys on the HT. There were no significant amino acid balance x ambient temperature effects on processing yields. The hypothesis of this experiment could be rejected as production performance did not respond positively to extra supplementation of lysine, methionine, and threonine when subjected to an HT.

Role of environmental temperature and photoperiod in regulation of seasonal testicular activity in the frog, Rana perezi.

To analyze the role of environmental temperature and photoperiod in the regulation of the annual testicular cycle in Rana perezi, we performed experiments combining high (25 +/- 1 degrees C) or low (6 +/- 1 degrees C) temperature and different photoperiod regimens (18L:6D, 12L:12D, and 6L:18D (hours light:hours dark)) during three phases of the reproductive cycle: winter stage (December) and prebreeding (February) and postbreeding (May, June) periods. Low temperature and short photoperiod in winter induced the arrest of the maturation phase of spermatogenesis and the activation of primary spermatogonia proliferation and spermiohistogenesis. Rana perezi testis responded to long days stimulus in winter, even at low temperature, with induction of the maturation phase of the cycle. Exposure of male frogs to either high temperature or long photoperiod induced a decrease in testosterone levels in winter. During the prebreeding period, an increase in environmental temperature caused a reduction in testosterone, and a lengthening in photoperiod produced the opposite effect. Photoperiod had no effect on testosterone levels during the postbreeding period, but low temperature increased testosterone plasma levels. These results suggest that both temperature and photoperiod effects can vary seasonally, depending on the phase of the annual reproductive cycle in R. perezi.

Longilarsus jacobaeae (Coleoptera: Chrysomelidae), a Flea Beetle for the Biological Control of Tansy Ragwort. 3. Comparison of the Biologies of the Egg Stage of Swiss and Italian Biotypes2

When the development of the eggs of 2 biotypes of Longitarsus jacobaeae (Waterhouse) was compared by exposing them to a daily regimen of 12 hr of light (24 ± 1°C) and 12 hr of dark (12.75 ± 1°C), as many as 85% of the Italian eggs (from Rome) hatched within 3 weeks; the Swiss eggs (from Delemont) entered diapause and took 15 weeks for 50% eclosion. Eggs from crosses were intermediate in longevity. However, the diapause of Swiss eggs was subsequently shortened an average of 1 week per generation because of inadvertent selection of progeny from early hatching eggs. Exposure of Swiss adults to 2 photoperiods (LD 12:12 and 16:8) did not affect the length of the egg diapause (11.4 vs. 12 weeks), and Italian adults held at the same 2 photoperiods continued to produce eggs that had 81 and 84% cumulative hatch, respectively, by the end of the 3rd week. Swiss eggs had higher mortality than Italian eggs when they were exposed to high temperature regimens (32.2°C for 12 hr and 12.75°C for 12 hr), to cool temperatures (10 and 7.2°C), to cold temperatures (3.3 and 0°C), and to a constant temperature of 24°C. Eggs of both strains required high humidity and frequent free water, and Italian eggs hatched at 80% RH only if they were wet daily to the point of saturation and at 95–100% RH only if they were wet or placed close to eggs that were wet daily.