The action of some systemic aphicides on the nymphs of Anthocoris nemorum (L.) and A. confusus Reut

The aphicides phorate, dimethoate and menazon were compared to elucidate the different pathways by which they can affect Anthocoris nymphs and their aphid prey.
When nymphs were caged in contact with deposits on bean leaves phorate and dimethoate had contact LC 50s of 20 and 3 μg/cm² respectively to Anthocoris nemorum and 46 and 6 μg/cm² to A. confusus. When the nymphs were confined on treated leaves on the opposite surface to the deposits, neither phorate nor dimethoate killed them. Menazon did not kill anthocorids at any dosage. All three aphicides killed over 50% of Acyrthosiphon pisum (Kalt.) on bean leaves at 1.6 μg/cm² whether the aphids were on the treated or untreated surface.
Experiments with ³⁵S-labelled phorate showed that anthocorids confined on phorate-treated bean plants, with or without insect food, accumulated the insecticide or its labelled derivatives. In field experiments in which A. nemorum were caged on plants treated with phorate, many were killed on young newly treated plants but not on older plants. A. confusus was relatively unaffected.
Anthocorids were reared from 2nd-instar nymphs to adults on aphids killed systemically with phorate, dimethoate or menazon without ill effects, despite evidence that ³⁵S-labelled phorate was ingested from the aphids and excreted in the faeces.
In the field, fewer large A. nemorum nymphs were found in August in plots of tick beans treated with phorate granules at 6 lb/acre (6.7 kg/ha) when sown, than in plots treated at 1.5 lb/acre (1.7 kg/ha) with phorate or menazon or untreated plots.     

STUDIES ON THE FEEDING OF MYZUS PERSICAE (SULZ.) ON RADIOACTIVE PLANTS

Adult apterae of Myzus persicae (Sulz.), were fed, after a period of fasting, on leaves containing radioactive phosphorus. The weight of sap imbibed by the aphids after varying feeding times was estimated by relating their radioactivity, at the end of each feeding period, to the activity per unit fresh weight of the leaf lamina on which they fed. The calculations were made on the assumption that ³²P is uniformly distributed in the leaf tissues.
The mean rates of uptake so estimated were about 10 μg. of sap for the first hour of feeding; 40 μg/hr. between 1 and 4 hr. feeding, and 17 μg./hr. between 6 and 24 hr. feeding. The decrease in apparent rate of uptake with the longer feeding times is attributed to loss of ³²P in nymphs born during the feeding period.
When aphids were fed on seedlings raised in water culture solution containing ³²P no activity was detected after 5 min. feeding and an insignificant fraction after 15 min., but when the isotope was introduced by immersing the leaves for several days in the culture solution, aphids fed for 5 and 15 min. became appreciably active.
The increase in rate of uptake after 1 hr. of feeding indicates that aphids do not start to feed normally until they reach the phloem, but the activity after short feeding times suggests that previously starved aphids feed to some extent on other tissues, possibly only on the epidermis.     

ON THE MECHANISM OF OUABAIN INHIBITION OF SYNAPTOSOME PROTEIN SYNTHESIS

Abstract— Ouabain (200μ m ) inhibited incorporation of radiolabelled leucine or glycine into the protein of neonatal synaptosome fractions but had minimal effect on preparations from adult rats. Leucine uptake into synaptosomes was rapid but not influenced by 200μ m -ouabain in contrast to ouabain inhibition of [¹⁴C]glycine and [¹⁴C]γ-aminobutyric acid uptake. Ouabain blocked the Na⁺ -dependent (stimulated) component of synaptosome fraction protein synthesis in the presence of 25m m -K⁺. Ouabain inhibition was not alleviated by addition of ADP or ATP. 100μ m -atractylate failed to influence [³H]leucine uptake or incorporation. Synergistic inhibition by ouabain was observed with the cycloheximide-sensitive component of protein synthesis and the chloramphenicol sensitive phase. Increasing the medium Ca²⁺ concentration stimulated protein synthesis and this stimulated component was inhibited by ouabain. Ouabain inhibition was associated with decreasing intraterminal K⁺ concentration and [K]_i was linearly related to the protein synthesis rate in control and ouabain treated preparations.     

THE EFFECTS OF OXYGEN DEPRIVATION ON ELECTRICALLY STIMULATED CEREBRAL CORTEX SLICES

Abstract— (1) Thin slices were prepared from guinea pig cerebral cortex and allowed to incubate in oxygenated bicarbonate-buffered medium for 30 min. Subsequent to that time the slices were made hypoxic by passing 95% N₂-5% CO₂ through the medium. Hypoxic exposure caused the slices to gain Na⁺ and to lose K⁺ ions from the non-inulin space. These shifts were especially pronounced when slices were electrically stimulated during the hypoxic period. Thus, after 30 min of hypoxia plus stimulation, non-inulin Na⁺ had risen from 30 to 84, μequiv./g wet wt., and non-inulin K⁺ had fallen from 50·5 to 14·3 μequiv./g wet wt.
(2) The above shifts were in part reversible, but when reoxygenated slices were subsequently electrically stimulated in oxygenated media, they failed to lose K⁺ or to gain Na⁺.
(3) The induced inexcitable state could not be attributed to inability of the slices to replenish ATP and phosphocreatine and may indicate an alteration in membrane constituents necessary for preservation of membrane excitability.     

STUDIES ON PLANT CUTICLE: THE CUTIN COMPONENT OF THE CUTICLES OF LEAVES

Methods are described for the chemical separation from leaf material of the ventral and dorsal surface cuticular membranes and for the determination of cutin in the membranes and leaf tissues.
The cutin contents of the cuticular membranes separated from leaves of laurel, rhododendron, and Euonymus , and of leaf tissues of cauliflower, red beet, banana, tomato, strawberry and blackcurrant are reported. The relationship between the cutin and waxy components of the leaf cuticle is discussed, and earlier work on the development, structure and chemistry of the cuticle is reviewed.     

Attraction of zebrafish, Brachydanio rerio, to alanine and its suppression by copper

Preference responses of zebrafish to 10⁻³, 10⁻⁴ and 10⁻⁵M alanine (Ala) were concentration- dependent. Behavioural responses to copper (Cu) and Cu + Ala mixtures were also assessed. Zebrafish avoided 100 and 10 μg Cu l⁻¹, but not 1 μg l⁻¹. Mixtures of 10⁻³ m Ala+ 100 μg Cu l⁻¹ and 10 ⁴ M Ala + 10 μg Cu 1⁻¹ were avoided as intensely as was Cu alone. Responses to 10⁻³ M Ala + 10 or 1 μg Cu l⁻¹ and 10 ⁴ M Ala +1 μg Cu l⁻¹ did not differ statistically from controls (no detectable preference or avoidance). These results demonstrate, firstly, that a concentration of a pollutant avoided by itself (10 μg Cu l⁻¹) may not be avoided when encountered with an attractant chemical stimulus (Ala) and may suppress the preference for an attractant stimulus, and secondly, that a concentration of a pollutant not avoided by itself and not considered deleterious (1 μg Cu l⁻¹) suppresses attraction to Ala (an important constituent of prey odours for many fishes).     

The Effects of Electroshock Convulsions on Calcium Transport within Synaptic Terminals

Abstract: Calcium transport was assessed within synaptic terminals isolated from cerebral cortices of rats which experienced one maximal electroshock (ES) convulsion daily. No significant change in calcium content [(Ca₁)] of synaptosomes was present after 2 consecutive days of maximal convulsions. After 4 and 6 days of maximal seizures, (Ca₁) rose 20% and 37%, respectively. ¹⁵Ca²⁺ influx within synaptosomes in vitro increased after 6 days of ES convulsions (1.94 ± 0.4 μmol/g protein/min in ES convulsions versus 1.54 ± .03 μmol/g protein/min in controls). The higher rate of ⁴⁵Ca²⁺ influx in convulsed animals was accounted for by elevated internal sodium [(Na₁)] values. Maximal ⁴⁵Ca²⁺ efflux decreased after ES convulsions (0.48 μmol/g protei/min in ES convulsions versus 0.8 μmol/g protei/min in controls). The slower rate of ⁴⁵Ca²⁺ efflux after convulsions was also accounted for by elevated (Na₁). Our results suggest that (Ca₁) increased within synapses after in vivo ES convulsions secondary to a primary ionic event, namely, elevated (Na₁).     

THE SELECTIVE NEURONAL UPTAKE AND RELEASE OF [3H]DL-2,4-DIAMINOBUTYRIC ACID BY RAT CEREBRAL CORTEX

Abstract— At 25°C the accumulation of [³H] dl -2,4-diaminobutyric acid (DABA) into small rat cortical slices was linear with time and a tissue: medium ratio of 35:1 was attained after 60 min. At 37°C the uptake was no longer linear and the tissue: medium ratio at 60 min was 66:1. Uptake was unaffected by the addition of 10 μ m -AOAA and dependent on the presence of Na⁺ in the incubation media. The uptake was shown to have a high affinity component with a K _m of 20.7 μ m and a V _max of 28.6 nmol/g/min. IC50's for the inhibition of [³H]DABA uptake by dl -DABA, l -DABA and GABA were 80, 40 and 17 μ m respectively. Two m m β -alanine, however, caused less than 13% inhibition of [³H]DABA uptake. Electron microscopic autoradiographs showed the [³H]DABA to be accumulated by 22% of the identifiable nerve terminals and, after 14 days exposure, the density of silver grains over nerve terminals was 36–38 times higher than that over the rest of the electron micrograph. On the other hand, [³H]DABA was not taken up into rat sensory ganglia and light level autoradiography showed the small amount of [³H]DABA accumulated by the ganglia to be evenly distributed throughout the tissue. Both electrical stimulation for 30 s and exposure of the tissue to a medium containing 47 m m -K⁺ for 2 min caused a marked increase in the efflux of [³H]DABA from the tissue. Both these effects were abolished by a reduction in Ca²⁺ concentration and an increase in the Mg²⁺ concentration of the superfusing medium. These results suggest that l -DABA acts as a 'false transmitter' for the neuronal uptake, storage and release of GABA.     

FIRST REPORT OF THE CYANOTOXINS CYLINDROSPERMOPSIN AND DEOXYCYLINDROSPERMOPSIN FROM RAPHIDIOPSIS CURVATA (CYANOBACTERIA)

A strain of Raphidiopsis (Cyanobacteria) isolated from a fish pond in Wuhan, P. R. China was examined for its taxonomy and production of the alkaloidal hepatotoxins cylindrospermopsin (CYN) and deoxy-cylindrospermopsin (deoxy-CYN). Strain HB1 was identified as R. curvata Fritsch et Rich based on morphological examination of the laboratory culture. HB1 produced mainly deoxy-CYN at a concentration of 1.3 mg·g ^{− 1} (dry wt cells) by HPLC and HPLC-MS/MS. CYN was also detected in trace amounts (0.56 μg·g ^{− 1}). A mouse bioassay did not show lethal toxicity when tested at doses up to 1500 mg dry weight cells·kg ^{− 1} body weight within 96 h, demonstrating that production of primarily deoxy-CYN does not lead to significant mouse toxicity by strain HB1. The presence of deoxy-CYN and CYN in R. curvata suggests that Raphidiopsis belongs to the Nostocaceae, but this requires confirmation by molecular systematic studies. Production of these cyanotoxins by Raphidiopsis adds another genus, in addition to Cylindrospermopsis , Aphanizomenon , and Umezakia , now known to produce this group of hepatotoxic cyanotoxins. This is also the first report from China of a CYN and deoxy-CYN producing cyanobacterium.     

Electrotransfection of Propionibacterium freudenreichii TL 110

The first highly efficient protocol is described for the electrotransfection of Propionibacterium freudenreichii with DNA phage. The transfection efficiency is 7 times 10⁵ transfectants per μg of DNA under optimal conditions. Optimized parameters included the field strength (12.5 kV, 200 Ohms, 25 μF), phage DNA concentration (1 μg ml^-1) and cell density (1.5 times 10¹⁰ cells ml^-1). Growth in the presence of glycine and harvesting of cells during the early exponential growth phase increased the transfection efficiency. This electrotransfection protocol is of importance for the genetic improvement of dairy propionibacteria.     

The effect of cryptolepine on the morphology and survival of Escherichia coli, Candida albicans and Saccharomyces cerevisiae

The antimicrobial activity of the indoloquinoline alkaloid, cryptolepine, isolated from Cryptolepis sanguinolenta (Fam. Periplocaceae) was determined against selected micro-organisms. The minimum inhibitory concentration (MIC) ranges obtained, expressed as μg ml⁻¹, were: 5–10 for Saccharomyces cerevisiae NCPF 3139; 10–20 for S. cerevisiae NCPF 3178; 20–40 for Escherichia coli NCTC 10418; 40–80 for E. coli NCTC 11560, Candida albicans ATCC 10231 and C. tropicalis NCPF; and 80–160 for C. albicans NCPF 3242 and NCPF 3262.
Biocidal effects were noted at concentrations 2–4 times those of the MIC of the alkaloid following challenge with 10⁶ cfu ml⁻¹ of micro-organisms. Time-kill studies showed a reduction in viable count from 10⁶ to < 10 cfu ml⁻¹ in 4 h in C. albicans ATCC 10231 exposed to 320 μg ml⁻¹ of the agent; 3 log cycle reductions were recorded for the 6 h counts of E. coli NCTC 10418 and S. cerevisiae NCPF 3139 exposed to 40μg ml⁻¹ and 160 μg ml⁻¹ of the alkaloid respectively.
These results were consistent with findings using scanning electron microscopy. Exposure of cells to biocidal concentrations of cryptolepine produced filamentation prior to lysis in E. coli NCTC 10418 and extreme disturbance of surface structure, including partial and total collapse, followed by lysis in C. albicans ATCC 10231 and S. cerevisiae NCPF 3139.     

The bacterial population of a blanket peat

The number of aerobic bacteria in a blanket peat decreased with depth from 26 times 10⁶/g dry peat in the surface layers to 0.5 times 10⁶/g dry peat at 30–40 cm down the profile, thereafter remaining roughly constant. Obligate psychrophiles comprised <2.5% of this population. Anaerobes were most numerous, 9 times 10⁶/g dry peat at 6–10 cm depth, decreasing to 0.5 times 10⁶/g at 20–30 cm. Calculations indicated that these counts, 10³–10⁴-fold lower than the direct counts, substantially underestimated the active microbial population. Gram negative rods, the predominant aerobes in the surface layers, were replaced by unidentified Bacillus strains at 10–20 cm depth but became increasingly more numerous further down the profile. The Gram negative rods were the most numerous organisms/m² but the Bacillus strains, one third of which were present as spores, made the largest contribution to the biomass/m². Gram positive cocci, Arthrobacter and, infrequently, Nocardia were also isolated. Actinomyces -like forms were the predominant obligate anaerobes and were approximately three times more numerous than clostridia and a curved Gram negative rod.     

Transformation of Streptococcus bovis protoplasts by plasmid DNA

M. MAREKOVÁ, V. KMET' AND P. JAVORSKÝ. 1996. The transformation and subsequent regeneration of ruminal strain Streptococcus bovis AO24/85 protoplasts by plasmid DNA was studied. The best stabilizer for regeneration of protoplasted cells was 5% sucrose in the regeneration medium and in the agar plates. Optimal concentration of polyethylene glycol 6000 in the transformation medium was 25% for both plasmids tested. Addition of Ca²⁺ and Mg²⁺ ions (2.5 mmol l^-1) to the transformation medium increased the proportion of regenerated cells. Transformation frequencies were 3 times 10³ transformants per μg of pNZ12 and 2.4 times 10² per μg of pJK108, respectively.     

RNA Synthesis and Processing during Cytodifferentiation in Fetal Rat Pancreas

In fetal rat pancreas cytodifferentiation occurs between day 14 and day 20 of gestation and is accompanied by an exponential increase in the cellular accumulation of tissue specific proteins and an elaboration of the cellular organelles associated with their synthesis and secretion. Evaluation of RNA synthesis by [³H] uridine incorporation into trichloroacetic acid precipitable material showed that during this period the apparent rate of RNA synthesis increased 7.5 fold from 2 × 10³ dpm/μg DNA/h on day 15 to 1.5 × 10⁴ dpm/μg DNA/h on day 19; [³H] leucine uptake showed that the rate of protein synthesis increased about the same extent with the major difference being that the maximum rate of protein synthesis occurred on day 19, one day after the maximum rate of RNA synthesis. The soluble pyrimidine nucleotide pools decreased from 122 pmol/μg DNA on day 14 to 15 pmol/μg DNA on day 16 followed by an increase to 104 pmol/μg DNA on day 19; the purine nucleotide pools decreased from 367 pmol/μg DNA on day 14 to 286 pmol/μg DNA on day 16 and then increased to 635 pmol/μg DNA on day 19. These values roughly paralleled the transitions observed in the rates of RNA and protein synthesis. Agarose-acrylamide slab gel electrophoresis showed an increase in RNA synthesis and an increase in ribosomal RNA synthesis and processing with cytodifferentiation.     

45Ca2+ Uptake into Rat Whole Brain Synaptosomes Unaltered by Dihydropyridine Calcium Antagonists

Abstract: Voltage-dependent ⁴⁵Ca²⁺ uptake into rat whole brain synaptosomes was measured after 3-s KCl-induced depolarization to investigate possible inhibitory effects of calcium antagonists, nitrendipine, nimodipine, and nisoldipine. At a Ca²⁺ concentration of 1.2 m M , nitrendipine, in concentrations ranging from 0.1 n M to 10 μ M , had no effect on ⁴⁵Ca²⁺ uptake. When the Ca²⁺ concentration was lowered to 0.06 and 0.12 m M , nitrendipine, 10 μ M , inhibited ⁴⁵Ca²⁺ uptake in response to 109 m M KCl depolarization. However, in a separate concentration response study, nitrendipine, nimodipine, and nisoldipine, 0.1 n M to 10 μ M , failed to alter the uptake of ⁴⁵Ca²⁺ (0.06 m M Ca²⁺) into 30 m M KCl-depolarized synaptosomes. The high concentrations of these agents required to depress ⁴⁵Ca²⁺ uptake indicate that the dihydropyridine calcium antagonists are considerably less potent in brain tissue than in peripheral tissue.     

Electrotransformation of whole cells of Brevibacterium sp. R312 a nitrile hydratase producing strain: Construction of a cloning vector

Abstract: A rapid and effective method is described for electroporation of Brevibacterium sp. R312, a coryneform strain producing nitrile hydratase and amidase. The transformation efficiency of the method is 10⁸ transformants per μg of plasmid under optimal conditions. Parameters optimised included field strength (11.8 kV cm⁻¹), pulse length (2.4 ms), plasmid DNA concentration (0.25 μg ml⁻¹ and cell density (10¹⁰ cells ml⁻¹). Surprisingly, the transformation efficiency did not vary with the growth stage, in contrast to results in the literature. A shuttle vector was constructed containing several unique cloning sites down-stream of the SP6 RNA polymerase promoter.     

Key Residues Defining the μ-Opioid Receptor Binding Pocket: A Site-Directed Mutagenesis Study

Abstract: Structural elements of the rat μ-opioid receptor important in ligand receptor binding and selectivity were examined using a site-directed mutagenesis approach. Five single amino acid mutations were made, three that altered conserved residues in the μ, δ, and κ receptors (Asn¹⁵⁰ to Ala, His²⁹⁷ to Ala, and Tyr³²⁶ to Phe) and two designed to test for μ/δ selectivity (Ile¹⁹⁸ to Val and Val²⁰² to Ile). Mutation of His²⁹⁷ in transmembrane domain 6 (TM6) resulted in no detectable binding with [³H]DAMGO (³H-labeled d -Ala², N -Me-Phe⁴,Gly-ol⁵-enkephalin), [³H]bremazocine, or [³H]ethylketocyclazocine. Mutation of Asn¹⁵⁰ in TM3 produces a three- to 20-fold increase in affinity for the opioid agonists morphine, DAMGO, fentanyl, β-endorphin_1–31, JOM-13, deltorphin II, dynorphin_1–13, and U50,488, with no change in the binding of antagonists such as naloxone, naltrexone, naltrindole, and nor-binaltorphamine. In contrast, the Tyr³²⁶ mutation in TM7 resulted in a decreased affinity for a wide spectrum of μ, δ, and κ agonists and antagonists. Altering Val²⁰² to Ile in TM4 produced no change on ligand affinity, but Ile¹⁹⁸ to Val resulted in a four- to fivefold decreased affinity for the μ agonists morphine and DAMGO, with no change in the binding affinities of κ and δ ligands.     

Mechanism of phosphorus-induced zinc deficiency in cotton. III. Changes in physiological availability of zinc in plants Is mail

The effect of varied supply of P (2.5× 10⁻⁵ to 6× 10⁻⁴ M) and Zn (0 to 10⁻⁶ M) on uptake and concentrations of P and Zn was studied in cotton ( Gossypium hirsutum L. cv. Deltapine 15/21) grown in nutrient solution under controlled environmental conditions. At a given Zn supply, increasing levels of P had no significant effect on the concentrations of total Zn in plants. However, increasing levels of P induced or enhanced visual Zn deficiency symptoms when the Zn concentration in the nutrient solution was low. The concentrations of water-soluble Zn in roots and shoots constituted 60% of the total Zn concentrations for plants grown with low P and 30% for plants grown with high P. The concentration of water-soluble Zn in leaves, but not total Zn, was closely correlated with visual Zn deficiency symptoms, levels of chlorophyll, super oxide dismutase and membrane permeability. The critical deficiency concentration of water-soluble Zn in cotton leaves was in the range of 6 to 7 μg (g dry weight)⁻¹ or about 1.0 μg (g fresh weight)⁻¹. The results show that high P concentrations in plant tissue decrease the physiological availability of Zn. Water-soluble Zn in the tissue appears to be a suitable indicator for Zn nutritional status in general and phosphorus-induced Zn deficiency in particular. Also in field-grown orange trees (Citrus sinensis) visual Zn deficiency symptoms in leaves were closely related to the concentration of water-soluble Zn.     

THE SYNTHESIS OF ACETYLCHOLINE BY THE OLIVOCOCHLEAR BUNDLE

Abstract— Choline acetyltransferase (ChAc; EC 2.3.1.6) was assayed in the membranous cochlea and in the eighth cranial nerve (both the vestibular and cochlear components) from the point where it leaves the brain stem to the internal auditory meatus of the cat. To determine the contribution of the efferent innervation of the cochlea to this enzymatic activity both eighth nerves and both membranous cochleae were assayed at 17–29 days following section of the right, crossed and uncrossed olivo-cochlear bundles (OCB) in the cat. The lesion was produced along the right sulcus limitans on the floor of the fourth ventricle. The left eighth nerves and cochleae served as controls in the ChAc assay. There was a significant decrease in ChAc activity in the right cochlea and eighth nerve after OCB section and degeneration. The mean activity of ChAc in the right cochleae of the 6 operated cats was 15 ± 7 μg of ACh formed. h⁻¹ (g wet wt. of tissue) ⁻¹ in comparison to the rate of all the intact cochleae of 156 ± 38 μg of ACh formed. h⁻¹. (g of tissue)⁻¹, a statistically significant difference ( P < 0005). The mean activity of ChAc in the right eighth nerves of the cats with OCB lesions was 30 ± 8 n-g of ACh formed. h⁻¹. (g of tissue)⁻¹in comparison to 91 ± 19 fig of ACh formed . h⁻¹. (g of tissue)⁻¹ found for intact eighth nerves. This difference was also significant ( P < 0005). Thus, section and degeneration of the crossed and uncrossed OCB reduce the activity of ChAc in the eighth nerve and membranous cochlea. This finding provides support for the hypothesis suggesting the cholinergic nature of olivo-cochlear transmission.     

Metabolic utilization of body stores during the early life of whitefish, Coregonus lavaretus L.

Patterns of oxygen consumption, ammonia and urea excretion were monitored during late embryogenesis, i.e. 5 days before mass hatching and 12 days during the free-swimming stage of whitefish larvae, Coregonus lavaretus. Oxygen consumption increased from 1.31 to 2.53 mgO₂ h⁻¹× 10³ eggs⁻¹ at hatching. Fasted, free-swimming larvae showed increasing oxygen consumption to the tenth day after hatching when it reached 5.52 mgO₂h⁻¹× 10³ larvae⁻¹. Ammonia and urea excretion increased during pre-hatching period from 52.1 to 163.2 and 26.8 to 51.4 μgh⁻¹× 10³ eggs⁻¹, respectively. The nitrogen excretion rate increased between the sixth and tenth day of fasting, i.e. for ammonia from 117.7 to 160.9 and for urea from 35.8 to 52.5 μg h⁻¹× 10³ larvae⁻¹. Cumulative data on nitrogen and energy metabolism indicated that during late embryogenesis, and up to the fifth day after hatching, protein dominated in the energy expenditure. During the free swimming stage, the ratio of fat to protein in energy expenditure rose from 0.86 to 1.99. Combined data for several fish species indicated high dependance of oxygen uptake during the hatching period on egg size and temperature.