Optimized protocol for the pilot-scale preparation of fungal cellulase

Summary A 25-l scale protocol is devised for the optimal secretion and recovery of fungal cellulase. Using a selected higher yieldingTrichoderma viride SMC strain, a protocol consisted of: a) an optimized production medium rich in microcrystalline cellulose (MCC), fortified with 1% (w/v) ammonium sulphate, 0.5% (w/v) soybean flour, 0.1% (v/v) Tween-80 and other trace nutrients; b) optimized physical parameters of production, such as an inoculum containing a homogeneous suspension of 6×10⁷ conidia per 1,28±1°C, pH 4.0±0.5, 300±20 rpm, 11000±1000 l/h aeration, and 170–220 h duration; c) optimal recovery through a filter press (450 l/h rate of filtration) followed by precipitation with 2.5–3.0 volumes of acetone (15°C and basket centrifugation (27°C, 1700 rpm)); and d) vacuum drying (35°C, 4–6 h). This afforded 70% recovery of cellulase in the form of white fluffy powder containing 20000±2000 carboxy methyl cellulase and 1000±50 units filter paperase per g activities, with raw material cost of US$ 8–10 per million carboxy methyl cellulase units. During storage for 18 months at 4°C, ambient temperature and 37°C, the cellulase preparation was found to retain 100, 75 and 60% of its initial activity, respectively.     

Sperm viability, motility and morphology in emus (Dromaius novaehollandiae) are independent of the ambient collection temperature but are influenced by storage temperature

A protocol for storage of emu semen >6 h has not yet been optimized. The objective was to determine: a) whether sperm quality was adversely affected by sudden exposure to low temperatures (5, 10 and 20 °C) during collection; and b) the effects of three storage temperatures (5, 10 and 20 °C) on survival of emu sperm. In two experiments, each repeated three times on alternate days, ejaculates were diluted 1:1 with precooled (5, 10, or 20°C) UWA-E3 diluent and stored for up to 48 h. Collection temperature, or interaction with either the storage time or storage temperature, had no significant effect on sperm viability, motility, or morphology. Mass Motility Score (2.91-3.27 ± 0.26, mean ± SEM), and percentages of live (72.4-76.2 ± 2.4) and morphologically normal sperm (63.3-64.5 ± 2.3) were comparable among collection temperatures. Conversely, storage temperature and storage time affected (P < 0.05) sperm viability, motility, and morphology. After storage for 48 h, percentages of viable, normal, and motile sperm were higher (P < 0.001) at 5 °C (58.7% ± 1.1, 44.7% ± 1.3, and 50.7% ± 4.9, respectively) and 10 °C (62.6% ± 1.1, 54.1% ± 1.3, and 60.4% ± 4.9) than at 20 °C (27.6% ± 1.1, 20.1% ± 1.3, and 25.9% ± 4.9). Beyond 6 h of storage, the percentage of abnormal sperm was higher (P < 0.001) for storage at 5 °C compared to 10 and 20 °C. After 48 h, bacterial counts were considerably higher at 20 °C compared to 5 and 10 °C (P < 0.001). The pH of stored sperm suspension remained unaffected at 5 and 10 °C, but at 20 °C declined to 6.5 ± 0.03 after 24 h (P < 0.05) and to 6.0 ± 0.03 after 48 h (P < 0.001). We concluded that emu semen could be collected at low ambient temperatures (5-20 °C) without compromising its in vitro storage duration and that semen quality during storage for 48 h was better if it was stored at 10 °C than at 5 or 20 °C.     

An optimized protocol for the production of high purity maltose

An economical protocol, which is simple, rapid and reproducible for the production of maltose by enzymatic hydrolysis of tapioca starch, has been optimized. The protocol involves liquefaction of 35% (w/w) tapioca starch by bacterial -amylase at 78±2°C to 3 to 5% (w/w) reducing sugars, followed by maximal (85±3% w/w maltose equivalent) saccharification with barley -amylase and pullulanase at 50°C for 24 to 30 h. The post-saccharification recovery protocol comprised decolourization by charcoal, de-dextrinization by denatured spirit precipitation, de-ionization by passage through cation and anion exchangers and dehydration by vacuum drying. A white crystalline maltose powder was obtained with specifications comparable to commercial high purity maltose. The protocol yields at least 60% (w/w) recovery of maltose and is suitable for use by the pharmaceutical industry. The protocol is unique in that it utilizes cheap and easily hydrolysed tapioca starch, leaves no mother liquor, enabling higher recovery of maltose, and allows almost quantitative recovery of limit maltodextrins, a value-added marketable by-product.     

A simple and rapid high recovery protocol for the purification of arginase

Summary A protocol of purification is devised that gave high recovery of homogeneous arginase from ox erythrocytes. The protocol involved haemolysis, heat treatment, CM- and DEAE-Sepharose chromatography, arginine AH-Sepharose chromatography and molecular sieving through Biogel P-150, all in the presence of 2-mercaptoethanol. It afforded (a) elution of arginase as a single peak, (b) almost 2900 fold purification, (c) 30% recovery and (d) electrophoretically homogeneous arginase. The purified arginase exhibited (a) M.W. of 115,000, (b) dissociation upon SDS treatment into homologous monomers of 30 kDa, (c) optimum pH and temperature 11.5 and 55° C, respectively and (d) Km value for L-arginine-HCl 2.2–2.3 mM, characteristic of the ureotelic type.     

Loss of heart phospholipid arachidonic acid without phospholipid peroxidation in anaesthetized rats rewarmed after prolonged deep hypothermia

Hypothermia–rewarming of the heart results in contractile dysfunction under in vitro as well as in vivo conditions. Increase in reactive oxygen species (ROS), lipid peroxidation and calcium overload are proposed mechanisms. In the first protocol of this study, the effect of putative phospholipase and calcium channel modulator mepacrine during deep hypothermia (4 h 14 °C) plus rewarming was tested in an isolated perfused rat heart model previously reported not to involve increase in lipid peroxides. Contractile function was measured under isovolumetric conditions using an intra-ventricular balloon connected to a transducer and recording system. Mepacrine completely reversed hypothermia–rewarming induced contractile failure in this model (LV dP/dt_max: 3236 ± 517 vs. 1058 ± 185 mm Hg/s in untreated hearts). In the second part of the study, lipid peroxidation of the heart was examined in vivo in anesthetized rats subjected to 4 h of deep hypothermia followed by rewarming. In this model recovery of heart function judged by cardiac output is decreased whereas blood pressure and heart rate recover fully. Peroxy conjugated diene isomers of unsaturated fatty acids were measured in heart phospholipids. The composition of the non-esterified fatty acids and the phospholipid fatty acid pool was examined in order to reveal signs of membrane remodeling. The results demonstrated no significant changes in phospholipid peroxidation after rewarming (91.07 ± 5.23 vs. 88.63 ± 7.73 nmol/g dry wt. in control). There was significant relative reduction in the content of arachidonic acid in the phospholipid fraction (29.55 ± 1.65 vs. 24.76 ± 1.48%). There was marked decrease in non-esterified fatty acids in myocardial tissue (1992 ± 291 vs. 1069 ± 189 nmol/g dry wt.), but a significant relative increase in arachidonic acid (20:4) in this fraction (3.46 ± 0.42 vs. 4.99 ± 0.30%). In conclusion, rewarming from deep hypothermia is not associated with increased phospholipid peroxidation. There is, however, a significant remodeling of the phospholipid fraction of myocardial lipids in vivo probably as a result of receptor or calcium stimulated phospholipase activity. Calcium or calcium stimulated phospholipase activity could contribute to posthypothermic contractile dysfunction.     

The Influence of Temperature on Metabolic and Cellular Protection of the Heart during Long-Term Ischemia: A Study Using P-31 Magnetic Resonance Spectroscopy and Biochemical Analyses

We have compared the influence of two different cold temperatures (below 10°C) for cardiac ischemia by measuring a large variety of hemodynamic and metabolic parameters during ischemia and reflow. Isolated isovolumic rat hearts were arrested with a preservation solution which was developed in our laboratory and then submitted to 5 h of cold storage (4°C, group I; and 7.5°C, group II) in the same solution. After an additional period of 50 min of ischemia at 15°C with intermittent cardioplegic infusion, hearts were reperfused for 60 min at 37°C. Function was assessed during the control period and reflow. High-energy phosphates and intracellular pH were followed by³¹P magnetic resonance spectroscopy. Analyses of metabolites and enzymes were performed by biochemical assays and HPLC in coronary effluents and in freeze-clamped hearts to assess cellular integrity. The energetic pool was better preserved at 4°C during ischemia (ATP at the end of 4°C ischemia, 59 ± 7% in group I vs 31 ± 5% in group II,P< 0.01) and reflow (P< 0.05) but membrane protection was higher when increasing the temperature to 7.5°C (reduction of creatine kinase leakage, 89 ± 16 IU/min in group I vs 51 ± 5 IU/min in group II,P< 0.05). As a result, functional recovery, represented by the rate pressure product, was higher in hearts preserved at 7.5°C (52 ± 6% recovery in group I vs 77 ± 7% in group II at the end of reflow,P< 0.05). Altogether, cold storage at 7.5°C provides a better protection than storage at 4°C.     

Water permeability properties of the ovarian oocytes from Bufo arenarum and Xenopus laevis: A comparative study

The water permeability properties of ovarian oocytes from Xenopus laevis and Bufo arenarum, a toad species found in the Buenos Aires region, were studied. We report that: (i) the water osmotic permeability (P _f, cm/sec × 10^–4) was significantly higher in Bufo (6°C=12.3±2.4; 18°C = 20.8±4.8) than in Xenopus oocytes (6°C=5.3±0.3; 18°C=6.2±1.6). The corresponding water diffusion permeability values (P _d, cm/sec × 10^–4) were: Xenopus = 2.3±0.3 (6°C) and 4.8±0.7 (18°C); Bufo=2.7±0.4 (6°C) and 6.0 ±0.5 (18°C). (ii) Amphotericin B increased the P _f and P _d values. The observed P _fP _d ratio was not significantly different from the expected results (n=3), after amphotericin B incorporation in both species. This means that the influence of unstirred layers and other potential artifactual compounds did not significantly affect our experimental results, (iii) Preincubation with gramicidin during 12 hr induced a clear increase in the oocyte volume. After that, a hypotonic shock only slightly increased the oocyte volume. Conversely, a hypertonic challenge induced a volume change significantly higher than the one observed in control conditions, (iv) Mercury ions did not affect the osmotic permeability in Xenopus oocytes but clearly inhibited, in a reversible way, the osmotic permeability in oocytes from B. arenarum. (v) Mercury ions did not reduce P _d values in either species, (vi) The P _fP _d values calculated from the differences observed in these parameters between both species were 11.9±5.1 at 18°C and 15.5±2.4 at 6°C. These numbers are similar to those previously reported in the case of membranes having water channels. From these results, we propose that water channels are present in the ovarian oocyte from B. arenarum but not in the ovarian oocyte from X. laevis.This work was supported by Fundación Antorchas, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Argentina) and Universidad de Buenos Aires (UBA). It was developed in the frame of an INSERM (France)-CONICET cooperative program.     

Recovery of photosynthetic reactions after high-temperature treatments of a heat-tolerant cactus

Inhibition and recovery of net CO₂ uptake and three photosynthetic electron transport reactions as well as plant survival following high-temperature treatments were investigated for Opuntia ficus-indica. For plants maintained at 30°C/20°C day/night air temperatures, treatment at 60°C for 1 h irreversibly inhibited net CO₂ uptake and photosynthetic electron transport, resulting in plant death in about 60 days. When a plant maintained at 30°C/20°C was treated at 55°C for 1 h, net CO₂ uptake was completely inhibited 1 d after the treatment but fully recovered in 60 d. Differential inactivation of photosystem (PS) I, PSII, and whole chain electron transport activities occurred; PSI was the most tolerant of 55°C and took the least time (45 d) for total recovery. All 30°C/20°C plants survived a 1-h treatment at 55°C, although some pale green areas were observed on the cladode surfaces. In contrast to growing at 30°C/20°C, plants acclimated to 45°C/35°C survived 60°C for 1 h without showing any necrotic or pale green areas on the cladode surfaces. When such a plant was transferred to 30°C/20°C following the high-temperature treatment, recovery in net CO₂ uptake began in 1 d and progressed to complete recovery by 30 d. Growth temperatures thus influence the possibility for recovery of photosynthetic reactions and ultimately the survival of O. ficus-indica following a high-temperature exposure.Abbreviations DCPIP 2,6-dichlorophenol indophenol - MV methyl viologen - PAR photosynthetically active radiation - PSI or PSII photosystem I or II - WC whole chain     

Seasonal and daily rhythms of body temperature in the European hamster (Cricetus cricetus) under semi-natural conditions

Body temperature of five European hamsters exposed to semi-natural environmental conditions at 47° N in Southern Germany was recorded over a 1.5-year period using intraperitoneal temperature-sensitive radio transmitters. The animals showed pronounced seasonal changes in body weight and reproductive status. Euthermic body temperature changed significantly throughout the year reaching its maximum of 37.9±0.2°C in April and its minimum of 36.1±0.4°C in December. Between November and March the hamsters showed regular bouts of hibernation and a few bouts of shallow torpor. During hibernation body temperature correlated with ambient temperature. Monthly means of body temperature during hibernation were highest in November (7.9±0.8°C) and March (8.2±0.5°C) and lowest in January (4.4±0.7°C). Using periodogram analysis methods, a clear diurnal rhythm of euthermic body temperature could be detected between March and August, whereas no such rhythm could be found during fall and winter. During hibernation bouts, no circadian rhythmicity was evident for body temperature apart from body temperature following ambient temperature with a time lag of 3–5 h. On average, hibernation bouts lasted 104.2±23.8 h with body temperature falling to 6.0±1.7°C. When entering hibernation the animals cooled at a rate of -0.8±0.2°C·h^-1; when arousing from hibernation they warmed at a rate of 9.9±2.4°C·h^-1. Warming rates were significantly lower in November and December than in January and February, and correlated with ambient temperature (r=-0.46, P<0.01) and hibernating body temperature (r=-0.47, P<0.01). Entry into hibrnation occured mostly in the middle of the night (mean time of day 0148 hours ±3.4 h), while spontaneous arousals were widely scattered across day and night. For all animals regression analysis revealed free-running circadian rhythms for the timing of arousal. These results suggest that entry into hibernation is either induced by environmental effects or by a circadian clock with a period of 24 h, whereas arousal from hibernation is controlled by an endogenous rhythm with a period different from 24 h.Abbreviations bw body weight - CET central European time - T _a ambient temperature - T _b body temperature - TTL transistor-transistor logic     

HPLC determination of tryptophan in foodstuffs using barium hydroxide hydrolysis at 140°C

Summary Hydrolysis of samples of food and feedstuffs with 2.7 N Ba(OH)₂ at 140°C for 4 h was tested for the recovery of tryptophan. On the basis of 100% yield for the tryptophan content, corresponding to samples determined after 16h-hydrolysis at 125°C, the recovery averaged 98.7 ± 0.9% SD or 99.4 ± 2% depending on how the bulk or aliquot of hydrolysate was analysed (conventional or simplified procedure). Tryptophan can be assayed by high performance liquid chromatography and fluorescence detection within 8h, 4h-hydrolysis at 140°C and a simplified procedure.     

Cryopreservation of canine epididymal sperm using ACP-106c and TRIS

The objective was to cryopreserve sperm recovered from the canine epididymal cauda immediately after an orchiectomy. The sperm was stored for 12 h at 4 °C using ACP-106c and TRIS as extenders. Sixty adult male dogs were used. The testis–epididymis complex (TEC) was removed, immersed in 0.9% saline and transported to the laboratory. The 60 TEC were divided into groups according to the 4 °C cooling time (0 h or 12 h) and according to the extender used for sperm recovery (ACP-106c or TRIS), forming 4 experimental groups: G0h-ACP, G12h-ACP, G0h-TRIS and G12h-TRIS. The sperm were recovered from the epididymal cauda using the retrograde flow technique. Next, 1.0 mL of ACP-106c or 1.0 mL of TRIS (preheated to 37 °C for 5 min) was added to the sperm of each epididymis. One week later, the sperm was thawed at 37 °C for 1 min, and its morphology, functionality and total and progressive sperm motilities were analyzed. Other parameters were obtained by Computer Assisted Semen Analysis (CASA). The data were submitted to multivariate analysis of variance (MANOVA) (P < 0.05). The total motility values were 52.17 ± 1.78 and 49.8 ± 1.93 for groups G0h-ACP and G12h-ACP and 50.7 ± 2.06 and 43.90 ± 2.51 for groups G0h-TRIS and G12h-TRIS, respectively. A decrease in total sperm motility was observed after 12 h of cooling for both extenders (P < 0.05). ACP-106c can be used as an extender for freezing canine epididymal sperm, and the freezing procedure must be performed immediately after sperm recovery.     

Sperm cryopreservation of the critically endangered olive barb (Sarpunti) Puntiussarana (Hamilton, 1822)

The present study focused on development of a sperm cryopreservation protocol for the critically endangered olive barb Puntiussarana (Hamilton, 1822) collected from two stocks within Bangladesh and reared in the Fisheries Field Laboratory, Bangladesh Agricultural University (BAU). The sperm were collected in Alsever’s solution prepared at 296 mOsmol kg⁻¹. Sperm were activated with distilled water (24 mOsmol kg⁻¹) to characterize motility. Maximum motility (90%) was observed within 15 s after activation, and sperm remained motile for 35 s. Sperm activation was evaluated in different osmolalities and motility was completely inhibited when osmolality of the extender was ?287 mOsmol kg⁻¹. To evaluate cryoprotectant toxicity, sperm were equilibrated with 5%, 10% and 15% each of dimethyl sulfoxide (DMSO) and methanol. Sperm motility was noticeably reduced within 10 min, when sperm were equilibrated with 15% DMSO, indicating acute toxicity to spermatozoa and therefore this concentration was excluded in further trials. Sperm were cryopreserved using DMSO at concentrations of 5% and 10% and methanol at 5%, 10% and 15%. The one-step freezing protocol (from 5 °C to −80 °C at 10 °C/min) was carried out in a computer-controlled freezer (FREEZE CONTROL® CL-3300; Australia) and 0.25-ml straws containing spermatozoa were stored in liquid nitrogen for 7–15 days at −196 °C. The highest motility in thawed sperm 61 ± 8% (mean ± SD) was obtained with 10% DMSO. The fertilization and hatching rates were 70% and 37% for cryopreserved sperm, and 72% and 62% for fresh sperm. The protocol reported here can be useful for hatchery-scale production of olive barb. The use of cryopreserved sperm can facilitate hatchery operations, and can provide for long-term conservation of genetic resources to contribute in the recovery of critically endangered fish such as the olive barb.     

Temperature and chiasma formation in Rhoeo spathacea var. variegata

A clone of Rhoeo spathacea var. variegata was exposed to a constant temperature of 37°C to examine the effects of high temperature on the chiasma frequency. Rhoeo was chosen for this study for its unusual meiotic chromosome configurations (rings and chains) at diakinesis and the first metaphase which permitted the calculation of terminal-chiasma frequency, and for its genetic homogeneity among plants in a clone. Plants treated for 12 h and 24 h at 37°C had similar mean terminal-chiasma frequencies to that of controls (10.93±0.11, 10.95±0.09 and 10.64±0.07 respectively), while those treated for 36 h, 48 h or 60 h had lower mean terminal-chiasma frequencies than that of controls (8.06±0.18, 4.25±0.15, 0.76±0.07 and 10.64±0.07 respectively). Analysis of variance was performed to find out whether the mean terminal-chiasma frequencies resulted from different treatments were significantly different from one another. The results of the analysis indicated that prolonged exposures to high temperature significantly reduced the chiasma frequencies.     

Favoring the birth of female puppies after artificial insemination using chilled semen diluted with powdered coconut water (ACP-106c)

The objective was to determine the effect of powdered coconut water extender (ACP-106c) on the proportion of female puppies born. Twenty French Bulldog bitches were subjected to natural mating (NM) and, during the subsequent two estrus periods, were bred by intravaginal artificial insemination (AI), using chilled semen (from the same males) diluted in Tris-egg yolk (AI-Tris) or ACP-106c (AI-ACP-106c). Fresh semen was cooled to 5 °C and maintained at that temperature for 6 h, rewarmed (37 °C for 30 s), and used for AI. Pregnancy and whelping rates following NM were both 100% and were both 90.0% following AI with either extender. Litter size (mean ± SD) was 5.4 ±1.1, 4.7 ± 2.0, and 5.1 ± 2.0 (P > 0.05) for NM, AI-Tris, and AI-ACP-106c, respectively. Furthermore, for these groups, the number of female vs. male puppies born were 2.6 ± 0.6 vs. 2.8 ± 1.0, 2.2 ± 1.0 vs. 2.5 ± 1.1, and 3.4 ± 1.6 vs. 1.8 ± 1.2 (P < 0.05 for AI-ACP-106c only). In conclusion, our hypothesis was supported; AI of semen in ACP-106c extender resulted in a significantly higher proportion of female puppies. Furthermore, this extender yielded acceptable litter size and rates of pregnancy and whelping.     

Egg production in response to combined alternative foods by the predator Coccinella transversalis

The peformance of the parasitoid Anagyrus kamali Moursi [Hymenoptera: Encyrtidae], as a function of host density, temperature, and photoperiod was investigated with the objective to optimize a mass-rearing system in the context of a biological control program. The number of hosts parasitized at densities varying from 2–100 hibiscus mealybug (HMB), Maconellicoccus hirsutus Green [Homoptera: Pseudococcidae], corresponded to a type II-III functional response in fixed-time conditions and a type III in variable-time conditions. Twenty-six percent of the oviposited eggs led to progeny emergence with a sex ratio of 0.49±0.102 (M/F), regardless of host density. Fecundity and oviposition period under six abiotic combinations (i.e., two temperatures (26±2 °C and 32±2 °C) and three photoperiods (L0:D24, L12:D12, L24:D0)) were measured. Lifetime fecundity and reproductive life were significantly affected by temperature and photoperiod conditions. Optimum female parasitoid lifetime fecundity was attained at 26±2 °C, L0:D24 with an average of 116.1±17.43 eggs. At 32±2 °C, L24:D0 and L12:D12, an average of 79.4±34.57 and 85.8±35.81 eggs were laid, respectively. Reproductive longevity was maximal at 26±2 °C, L0:D24 with 12±4.85 days of oviposition. Because the parasite A. kamali can be reared optimally without light, this may save tremendous energy costs.     

Comparative cryopreservation study of trochophore larvae from two species of bivalves: Pacific oyster (Crassostrea gigas) and Blue mussel (Mytilus galloprovincialis)

Oysters and mussels are among the most farmed species in aquaculture industry around the world. The aim of this study was to test the toxicity of cryoprotective agents to trochophore larvae from two different species of bivalves and develop an improved cryopreservation protocol to ensure greater efficiency in the development of cryopreserved trochophores (14 h old oyster larvae and 20 h old mussel larvae) to normal D-larvae for future developments of hatchery spat production. The cryopreservation protocol producing the best results for oyster trochophores (60.0 ± 6.7% normal D-larvae) was obtained by holding at 0 °C for 5 min then cooling at 1 °C min⁻¹ to −10 °C and holding for 5 min before cooling at 0.5 °C to −35 °C, holding 5 min and then plunging into liquid nitrogen (LN), using 10% ethylene glycol. For mussel experiments, no significant differences were found when cooling at 0.5 °C min⁻¹ or at 1 °C min⁻¹ for CPA combinations with 10% ethylene glycol and at 0.5 °C min⁻¹. Using these combinations, around half of trochophores were able to develop to normal D-larvae post-thawing (48.9 ± 7.6% normal D-larvae).     

Energieumsatz in Abh?ngigkeit von der Umgebungstemperatur beim KolibriOcreatus u. underwoodii

Zusammenfassung Bei der südamerikanischen KolibriartOcreatus u. underwoodii (2.7 g±0.09 SD, n=3) wurde der Ruhe- und Flugstoffwechsel in Abhängigkeit von der Umgebungstemperatur (3° bis 34° C) bei Licht und ohne Nahrungsentzug untersucht, sowie der stündliche Energieverbrauch ermittelt.1. Der Ruhestoffwechsel stieg linear bei fallender Umgebungstemperatur (r=0.95±0.04 SD, n=3).2. Der Flugstoffwechsel zeigte eine dem Ruhestoffwechsel entsprechende Abhängigkeit von der Umgebungstemperatur.3. FürOcreatus u. underwoodii wurden für Sitzen bzw. Fliegen mit 199.2 mW/g bzw. 325.3 mW/g die höchsten für homöotherme Tiere bisher ermittelten Wärmeproduktionsraten gemessen.4. Im getesteten Umgebungstemperaturbereich schwankte die Körpertemperatur bei den drei Individuen zwischen 38.8° und 39.9° C.5. Der für 25° C Umgebungstemperatur berechnete Energieverbrauch betrug ca. 1030 J/h.6. Zur Deckung des Energiebedarfs mußOcreatus u. underwoodii stündlich z. B. 205Salvia-Blüten besuchen.

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Energetical responses to various ambient temperatures in the hummingbirdOcreatus u. underwoodii

Summary Metabolism of resting and flyingOcreatus u. underwoodii (2.7 g±0.09 SD, n=3) was measured at varying ambient temperatures (3°–34° C). All experiments were conducted in light. In the metabolic chamber the bird had access to food. The caloric expenses were calculated for one hour.1. Metabolism of restingOcreatus u. underwoodii increased linearly with falling ambient temperature (r=0.95±0.04 SD, n=3).2. During flight O₂-consumption showed the same relation to ambient temperature as in resting birds.3 With 199.2 mW/g for resting and 325.3 mW/g for flight the highest rates for heat production in homeothermic animals were registrated.4. In the tested range of ambient temperature body temperature varied in all 3 individuals from 38.8° to 39.9° C.5. The caloric expenses at 25° C ambient temperature, the most commonly experienced temperature in the natural environment of this hummingbird species, were about 1030 J/h.6. To gain its energy requirementsOcreatus u. underwoodii has to visit e. g. about 205 Salvia flowers per hour.

     

Hormonal growth-promotant effects on grain-fed cattle maintained under different environments

Six steers (3/4 Charolais×1/4 Brahman) (mean body weight 314±27 kg) and six spayed heifers (3/5 Shorthorn×2/5 Red Angus) (mean body weight 478±30 kg) were used to determine the effects of climatic conditions and hormone growth promotants (HGP) on respiration rate (RR; breaths/min), pulse rate (beats/min), rectal temperature (RT; °C), and heat production (HP; kJ). Cattle were exposed to the following climatic conditions prior to implantation with a HGP and then again 12 days after implantation: 2 days of thermoneutral conditions (TNL) [21.9±0.9°C ambient temperature (T_A) and 61.7±22.1% relative humidity (RH)] then 2 days of hot conditions [HOT; 29.2±4°C (T_A) and 78.3±13.2% (RH)], then TNL for 3 days and then 2 days of cold conditions [COLD; 17.6±0.9°C (T_A) and 63.4±1.8% (RH); cattle were wet during this treatment]. The HGP implants used were: estrogenic implant (E), trenbolone acetate implant (TBA), or both (ET). Both prior to and following administration of HGP, RRs were lower (P<0.05) on cold days and greater (P<0.05) on hot days compared to TNL. On hot days, RTs, were 0.62°C higher after compared to before implanting. Across all conditions, RTs were >0.5°C greater (P<0.05) for E cattle than for TBA or ET cattle. On cold days, RTs of steers were >0.8°C higher than for the heifers, while under TNL and HOT, RTs of steers were 0.2–0.35°C higher than those of heifers. Prior to implantation, HP per hour and per unit of metabolic body weight was higher (P<0.05) for cattle exposed to hot conditions, when compared to HP on cold days. After implantation, HP was greater (P<0.05) on hot days than on cold days. Under TNL, ET cattle had the lowest HP and greatest feed intake. On hot days, E cattle had the lowest HP, and the highest RT; therefore, if the potential exists for cattle death from heat episodes, the use of either TBA or ET may be preferred. Under cold conditions HP was similar among implant groups.     

Effects of sodium gluconate and phytase on performance and bone characteristics in broiler chickers

An experiment was conducted to evaluate the effects of corn soybean meal diets with added sodium gluconate (0 and 20 g/kg) and phytase (0, 500 and 1000 U/kg) on performance and bone characteristics of broiler chicks. A total of 350 eight-day-old Arbor Acre male chicks were used with a 2 × 3 plus 1 factorial arrangement. A positive control diet, adequate in non-phytate-phosphorus and calcium without sodium gluconate and phytase, was used. Chickens were randomly allocated to seven treatments with each treatment having five replicates. The experiment lasted from 8 to 42 d posthatching. The outcomes of the study indicated that the low-non-phytate-phosphorus diet caused a negative effect (P<0.05) on the average daily gain, average daily feed intake, tibia weight and tibia ash of birds compared to the positive control diet. The supplementation of 20 g sodium gluconate/kg increased average daily gain during days 22–42 (P=0.005), 8–42 (P=0.013) and tibia ash at 21 d (P=0.002). Phytase addition improved (P<0.05) average daily gain and average daily feed intake during the whole experiment and tibia weight, tibia ash at 21 and 42 d and calcium content in tibia ash at 42 d. Compared with diets supplemented with 500 U phytase/kg, diets supplemented with 1000 U phytase/kg had significantly higher average daily feed intake during the whole experiment and average daily gain during days 22–42 and 8–42 and tibia ash at days 21 and 42. There was a significant interaction between sodium gluconate and phytase for average daily gain (P=0.027) from 8 to 21 d and tibia weight (P=0.020) at 42 d. These results demonstrated that sodium gluconate and phytase supplementation to low-phosphorus diets improved performance and phytate-phosphorus utilization by chicks during the whole growing periods.     

Cultivation of Candida langeronii in sugar cane bagasse hemicellulosic hydrolyzate for the production of single cell protein

Sugar cane bagasse hemicellulosic fraction was hydrolysed by treatment with 70 mg of sulphuric acid per gram of dry mass at 125 °C for 2 h. The hydrolysate was used as the substrate to grow Candida langeronii RLJ Y-019 at 42 °C; initial pH 6.0; stirring at 700 rev/min and aeration at 1.0 and 2.0 v/v/min. The utilization of D-xylose, L-arabinose, and acetic acid were delayed due to the presence of D-glucose, but after D-glucose depletion the other carbon sources were utilized. The kinetic parameters calculated for both cultivations at 1.0 and 2.0 v/v/min included: maximum specific growth rate (_max) of 0.29 ± 0.01 h^–1 and 0.43 ± 0.016 h^–1, yields (Y _x/s) of 0.36 ± 0.012 and 0.40 ± 0.012 g_x/g_s and productivity (Q _x) of 0.81 ± 0.016 and 0.97 ± 0.012 g_x/l/h, respectively, and compared favourably with published results obtained with Candida utilis and Geotrichum candidum. Candida langeronii appeared superior to C. utilis for biomass production from hemicellulose hydrolysate, in that it utilized L-arabinose and was capable of growth at higher temperatures. The biomass contained 48.2, 1.4, 5.8 and 23.4% of total protein, DNA, RNA and carbohydrate, respectively and contained essential amino acids for animal feed.