Effect of light intensity on sporulation of Botryosphaeria ribis

Pycnidia were produced by six of seven isolates ofB. ribis at one or more intensity levels of continuous illumination at 21 °C. Under conditions of alternating light (12 h–27 °C) and darkness (12 h–21 °C) pycnidia formed in cultures of six isolates at three or more intensity levels, while one isolate failed to form pycnidia at any intensity level. Pycnidia did not develop when cultures were incubated in complete darkness. Exposure periods as brief as 2 days under continuous illumination at 21 °C induced pycnidial formation. In alternating light (12 h–27 °C) and darkness (12 h–21 °C), the shortest period of exposure which induced pycnidial formation was 4 days. Continuous illumination at 21 °C favored development of uniloculate pycnidia, while alternating light (12 h–27 °C) and darkness (12 h–21 °C) favored formation of multiloculate pycnidia.Contribution No. 22 from The Botany Section of The Department of Biology, The Pennsylvania State University.     

Retinal alterations induced by continuous light in immature rats

Immature albino rats were exposed to continuous illumination for 5-93 days and the light induced ultrastructural and electroretinographic changes were studied. Another group was exposed to continuous light for 7-9 days and then kept in complete darkness, or in cyclic light-dark up to 90 days. By comparison with the results obtained in adult animals, lesions appeared faster in the immature group. Tubular transformation of rods, phagocytosis of altered outer and inner segments with resulting changes in retinal organization, synaptic degeneration in the outer plexiform layer, and cell lysis of some photoreceptor cell perikarya are described. ERG recovery, following the period of darkness or cyclic light-dark was only partial, the amplitude of the "b" wave reached only 50-60% of the control preillumination values. However, the fine structure of the recovered outer segments was similar to that found in normal retinae.     

Effects of temperature on the darkness survival of marine microplanktonic algae

Thirty-seven species of marine microplanktonic algae from 10 taxonomic classes were tested for their viability in axenic culture after prolonged exposure to darkness at 2°, 10°, and 20°C. The darkness test periods were prolonged in weekly installments up to a maximum of 1 year, and viability retention (survival) was judged from the capability for resuming growth after replacement in light. The 2°C-tests showed 32% of the species reaching the limits of survival with 5–6 months of darkness exposure, but another similar percentage continued to tolerate darkness for double this period. These darkness toleration limits were considerably shorter at 20°C for the strains known to be isolated from cold marine regions, whereas the warm-water strains showed the reverse temperature effect in surviving significantly longer at 10°–20°C than at 2°C. Irrespective of temperature or algal class, the bulk of the more resistant survivors was formed by the strains qualifying as benthic types, about 70% of which tolerated 11–12 months and the rest at least 5–6 months of darkness. A few randomly chosen benthic strains extended this toleration to 3 years of darkness. It was concluded that phytoplankters retain darkness-endurance capacity determined by their ecological origin and with no obvious taxonomic correspondence. The concept of ecological races, characterized by temperature control of darkness survival, is discussed.The termdarkness-survival is used throughout this report to denote the retention of cellular viability by an algawithout growth (i.e., without significant increase in cellular mass or numbers) during exposure to darkness. Implicit in this definition is the denial of any known possibility of growth, either autotrophic requiring light or heterotrophic requiring organic-carbon, since both these agents are effectively absent in the survival cases considered here.     

ZIO staining in synaptic vesicles of the rat pineal nerves after inhibition of serotonin and noradrenaline synthesizing enzymes

Summary Two compartments have been defined in monoaminergic synaptic vesicles: the core or central compartment, storage site for monoamines, and the matrix or outer compartment, of unknown function. The outer compartment reacts with the mixture of zinc iodide-osmium tetroxide (ZIO). This reaction is temperature and time dependent and may be abolished by -SH reagents.The effect of drugs inhibiting the synthesis of serotonin and noradrenaline (stored in the core) on the ZIO reaction in the matrix was studied in synaptic vesicles of rat pineal nerves. The inhibitors of monoamine synthesis abolish or decrease the ZIO reaction directly or in combination with the administration of tyramine. This effect is temperature dependent suggesting that the drugs act on different components of the matrix that react with ZIO at different temperatures. A comparison of the present results with those obtained with -SH reagents seems to indicate that the drugs assayed act, at least in part, by changing the accessibility of-SH groups in vesicle proteins. (An abstract of this paper was presented at the 7th International Congress of Pharmacology, Paris, 1978.)Supported by grants from the Consejo Nacional de Investigaciones Cientificas y Técnicas, CONICET, and the Secretaría de Ciencia y Técnica, SECYT, ArgentinaWe are grateful to Margarita López de Cáceres for technical assistance, to Adriana Contreras for the electron micrographs and to María Aued de Rau for the illustrations. Rita Cardoni is a fellow of the Consejo Nacional de Investigaciones Cientificas y Técnicas, Argentina     

Influence des facteurs physiques et nutritifs sur le développement des sporanges et des sporangioles du Blakeslea trispora thaxter

Résumé L'effet des facteurs physiques et nutritionnels sur la production de sporanges et de sporangioles chezB. trispora a été étudiée. D'après les résultats les besoins nécessaires au développement de ces deux formes asexuées sont différents. Une température basse de 14° C et une illumination continue constituent les conditions optimales pour la production des sporangioles. Au contraire on obtient une meilleure formation des sporanges avec une température élevée (25°–30° C), et une illumination discontinue ou bien à l'obscurité. Les sporanges sont totalement absents à 14° C. Le milieu solide PDA est meilleur que le milieu synthétique liquide pour la sporulation du champignon.La croissance et la sporulation chez les cultures sur eau de pomme de terre gélosé (PDA) exposées à l'action continue de rayons ultra-violets à 14° C ont été presque normales. Si ce milieu est remplacé par l'extrait de malt gélosé (Difco), la croissance et la sporulation sont ralenties pendant les quatre premiers jours et le nombre de sporangioles unisporées est plus élevé.

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The effect of physical and nutritional factors on the production of sporangia and sporangioles inB. trispora has been studied. The results showed that the requirements for the development of these structures were different. At 14° C, the production of sporangioles was excellent. Sporangia were altogether absent at this temperature. On the other hand, sporangia were produced fairly well at higher temperatures (25°–30° C), whereas sporangioles were totally absent. Sporangioles were present in insignificant number at 23° C. At 14° C, the production of sporangioles was better in continuous light than in complete darkness. At 18° and 21° C, the continuous light favoured the production of sporangioles and prevented significantly the formation of sporangia.The synthetic liquid medium used in the present investigation was not found to be good for sporulation, whereas potato dextrose agar medium proved to be a suitable medium for the study of asexual structures in this fungus. The results of the study of the effect of ultraviolet rays at 14° C, showed that with PDA there was no significant difference in the degree of sporulation between the cultures grown in the presence and in the absence of ultraviolet rays. But with malt extract agar medium (Difco), the production of sporangioles containing only one spore was stimulated by the ultraviolet rays.

     

Repeated reversal of the reproductive diapause by photoperiod and temperature in males of the grasshopper, Oedipoda miniata

Short day-length and relatively low temperatures (LD 10.5 : 13.5, 26° during illumination, 13° during darkness) induced mating behaviour and terminated aestival reproductive diapause in males of the grasshopper Oedipoda miniata. Long days and high temperatures (LD 16 : 8, 38° during illumination, 27° during darkness) maintained sexual inactivity and diapause. Repeated changes of these conditions terminated, reinduced, reterminated and reinduced again diapause in the same males. An endogenous trend to complete diapause development and terminate diapause does not seem to exist in the males of this grasshopper; their reproductive diapause may be regarded as rather primitive.

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Résumé Les jours courts et les températures relativement basses (J/N; 10,30/13,30; 26°/13°) induisent le comportement sexuel et achièvent la diapause reproductrice estivale des mâles de l'Acridien Oedipoda miniata. Les jours longs et les températures élevées (J/N; 16/8; 38°/27°) inhibent l'activité sexuelle et provoquent la diapause.Des changements répétés de ces conditions achèvent, réinduisent, achèvent à nouveau et réinduisent à nouveau la diapause chez les mêmes mâles. Une tendance endogène pour achever le déroulement de la diapause et terminer la diapause ne semble pas exister chez les mâles de cette espèce, leur diapause reproductrice peut être considérée comme plutôt primitive.

     

A bimodal temperature response and effect of light intensity in the photocontrol of germination of seeds in Jussiaea suffruticosa

Summary A bimodal temperature response is observed in the germination of seeds in Jussiaea suffruticosa, both under continuous and cyclic light treatments. Germination exhibits two maxima at around 25° C and at 40°, and a minimum in the region of 30–35°. The response depends on light intensity both under continuous and intermittent light treatments. This dependence is much more noticeable in the region of minimum germination (30°). Both preincubation in darkness at 35° and high light intensities (15 500 lux) tend to eliminate the bimodal temperature response.     

Morphological changes induced by -SH reagents in rod photoreceptor outer segments

Summary Rat retinas were treated in vitro with -SH reagents and stained with zinc iodide-osmium tetroxide (ZIO). Dithioerythritol (DTE), an -S-S-reducing agent, increased the electron opaque deposits observed after ZIO staining in the intraand extradiskal spaces of the rods. N-ethyl-maleimide (NEM), an -SH blocking agent, applied directly or after DTE, blocks the ZIO reaction. Furthermore, after treatment with NEM, distorted tubular and vesicular structures are substituted for the stacks of disks. These results strongly suggest that ZIO reacts with -SH groups in rod outer segments. They also indicate that SH-groups play an important role in the structural organization of rod outer segments.Supported by Grants from the Consejo Nacional de Investigaciones Cientificas y Técnicas, Argentina and Fight for Sight, Inc. N.Y. United StatesI am grateful to Miss Margarita López for her skilful technical assistance and to Mr. Alberto Saenz for the electron micrographs     

Horizontal reactor for the continuous production of ethanol by yeasts immobilized in pectin

Summary Yeast cells (Saccharomyces cerevisiae) were immobilized in pectin gel, incubated 12 h at 30°C and then used for the continuous production of ethanol employing a wedge-shaped horizontal reactor and sugar cane molasses as the carbon source. Under steady state conditions the mean residence time was 1.6 h and the volumetric productivity 40 g EtOH/hl. The gas evolved was easily released. Successive batch incubation in a synthetic medium substantially restored the fermentative capacity of the beads already used in the continuous assay.Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del IPN, México D.F.Member of the Scientific Researcher's Career of the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina.     

Germination characteristics ofDiamorpha cymosa seeds and an ecological interpretation

Summary Laboratory-stored seeds ofDiamorpha cymosa (Nutt.) Britton (Crassulaceae) were germinated at monthly intervals starting shortly after maturity in late May and ending at approximately the time germination is completed in the field (November). Seeds were placed at 5, 10, 15, 20, 25, 30, 15/6, 20/10, 30/15 and 35/20°C at a 14-hr photoperiod (12/12 hr thermoperiods at the alternating temperature regimes) and in constant darkness. In June, seeds were almost completely dormant and thus germinated poorly or not at all under all conditions. As seeds aged from late May to November 1. germination at the 14-hr photoperiod increased in rate and total percentage, 2. the maximum germination temperature increased from 15 to 25°C at constant temperatures and from 20/10 to 30/15°C at the alternating temperature regimes and 3. the optimum temperature for germination increased from 15 to 15–20°C at constant temperatures but remained at20/10°C at alternating temperature regimes throughout the study. During the same period germination in constant darkness was negligible at constant and alternating temperature regimes. This pattern of physiological after-ripening apparently is an adaptation to summer-dry,winter-wet habitats such as rock outcrops of southeastern United States.A short period of illumination with white light given after a 12-hr imbibition period in darkness promoted germination in the dark at 25/10°C but not at 15 or 25°C. A short period of illumination given during the imbibition period was much less effective in promoting germination in the dark. Drying up to 7 days did not cause light-stimulated seeds to lose their ability to germinate in darkness. The light requirement for seed germination probably does not play a role in restrictingD. cymosa to its well-lighted habitats on granite and sandstone outcrops.This research was supported by funds from the University of Kentucky Research Foundation and by an NIH Biomedical Sciences Support Grant to the University of Kentucky.     

Diets for rearing the ambrosia beetle of tea, Xyleborus fornicatus (Coleoptera: Scolytidae), in vitro

An artificial diet consisting of sucrose, casein, yeast extract, tea bark extract and cellulose powder was suitable for rearing Xyleborus fornicatus Eichh. through several successive generations in the laboratory. Since the flightless adult male progeny seldom emerged, diet evaluations were based on the number of emerging adult female progeny. At 28° and 75% R.H. the emergence of progeny adult females occurred 40–70 days after the date of inoculation of the parent female. The number emerging from these laboratory cultures far exceeded the average brood size observed under field conditions. Cellulose powder was found to offer the critical physical consistency needed for tunnelling.At 75% R.H., the beetles bred successfully in the temperature range of 24°–32°. Under uniform laboratory conditions in total darkness, emergence followed a definite rhythm, with peak emergence at 12.00 h. Since the observations were made on the progeny of beetles reared continuously in the laboratory in total darkness for more than ten generations, such a rhythm appears to be an in-born endogenous character that is independent of external environmental variations.

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Résumé Xyleborus fornicatus a pu être élevé pendant plusieurs générations successives sur un aliment artificiel constitué par du sucrose, de la caséine, de l'extrait de levure, de l'extrait d'écorce de thé et de la poudre de cellulose.A 28° et pour une H.R. de 75% l'émergence des premiers imagos femelles intervient 40 à 70 jours après la mise en élevage de la femelle pondeuse. Le nombre de femelles issues de ces élevages en laboratoire est beaucoup plus élevé que le nombre moyen de descendants observés dans les conditions naturelles. La poudre de cellulose s'est révélée offrir la bonne consistance physique, nécessaire au creusement des galeries.Pour une H.R. de 75%, les insectes se reproduisent normalement, dans une gamme de température comprise entre 24° et 32°. Sous les conditions uniformes du laboratoire, dans l'obscurité totale, l'émergence des imagos se manifeste selon un rythme défini, avec un pic à midi. Un tel rythme semble être de nature endogène et innée, indépendant des variations du milieu extérieur.

     

The coupling effects of some thiol and other sulfur-containing compounds on the circadian rhythm of cell division in photosynthetic mutants of Euglena

Previous work has demonstrated a persisting, free-running, circadian rhythm of cell division in the P₄ZUL photosynthetic mutant of the alga Euglena gracilis Klebs (Strain Z) Pringsheim grown organotrophically in continuous light or darkness at 19° C following prior synchronization by a repetitive LD: 10,14 light cycle. A similar circadian rhythmicity has been recently discovered in the W₆ZHL heat-bleached and the Y₉ZNalL naladixic acid-induced mutants of Euglena grown under comparable conditions. Over extended timespans, however, these mutants appear to gradually lose first their ability to display persisting overt rhythms, and then even their capability of being entrained by imposed LD cycles. These properties can be restored by the addition of certain sulfur-containing compounds to the medium including cysteine, methionine, dithiothreital, sodium monosulfide, sodium sulfite, and sodium thiosulfate, as well as thioglycolic [mercaptoacetic] acid. The implications of these findings toward biological clock mechanisms are discussed: It appears that some sort of coupling process is operating as opposed to the initiation of an underlying oscillation.Non-Standard Abbreviations LL continuous illumination - DD continuous darkness - LD repetitive light-dark cycle - SS stepsize - period of biological rhythm Supported by research grants (GB-36287, GB-43543) from the National Science Foundation.Reports on portions of this work were presented at the 19th Annual Meeting of the Biophysical Society, Philadelphia, Pennsylvania, February 19–21, 1975; at the XII International Botanical Congress, Leningrad, U.S.S.R., July 3–10, 1975; and at the XII International Conference of the International Society for Chronobiology, Washington, D.C., August 10–13, 1975.     

Photocontrol of Spirodela intermedia flavonoids

Clone 115 of Spirodela intermedia W. Koch grown in Hutner's medium with sucrose produces the glycoflavones vitexin and orientin in darkness or in light of various wavelengths. The anthocyanin cyanidin-3-monoglucoside was present only after prolonged illumination of the plants with white or blue light. No cyanidin-glucoside was formed under constant red light. The substitution of red, blue, or far-red light for the last 24 hours of culture under constant white light reduced each flavonoid over those maintained in white light or given 24 hours of darkness. Reducing the light intensity from 900 to 400 ft-c of constant cool-white fluorescent light had no appreciable influence on vitexin (4′-hydroxyl) but markedly reduced orientin and cyanidin-glucoside (both 3′4′-hydroxyl). Substituting alternate 12-hour periods of light and darkness for continuous light reduced the glycoflavones approximately 50% while cyanidin-glucoside was reduced about 85%. Most responses to red, blue, or far-red light are consistent with a phytochrome-controlled promotion of vitexin synthesis.

The evidence suggests that in S. intermedia: A) Environmental conditions which elicit cyanidin-glucoside and glycoflavone synthesis are different since a prolonged illumination with white light is required for the former but not the latter. B) The availability of a 3′4′-hydroxyl precursor for orientin and anthocyanin probably limits their synthesis in low intensity light. Since vitexin is essentially unaltered under these conditions this also suggests that acetate or malonate units for the A-ring and the deamination products of aromatic amino acids for the B-ring and carbons of the C-ring are not limiting factors. C) Light controls the biosynthesis of flavonols in the same manner as glycoflavones; under all experimental conditions the synthesis of kaempferol paralleled vitexin while quercetin responded in the same manner as crientin.

     

Effect of incubation temperature on zearalenone production by strains of Fusarium crookwellense

After 6 weeks incubation on rice 2 strains of Fusarium crookwellense produced more zearalenone (6060–5010 mg/kg dry wt of culture) at ambient temperature (16–29°C) in daylight than at ambient temperature (18–23 °C) in darkness or at controlled temperatures of 11 °C, 20 °C or 25 °C in darkness. Yields at 25 °C were low. Incubation at 11 °C during the second 3 weeks incubation increased yields only when preliminary incubation had been at 25 °C. After 6 weeks incubation at controlled temperatures in darkness, 4 strains produced most zearalenone at 20 °C (2460-21 360 mg/kg), 1 strain at 11 °C (6570 mg/kg). Yields at a temperature oscillating daily from 10–20 °C were less than at 15 °C. One of the 5 strains produced appreciable amounts of a-zearalenol (1645 mg/kg at 20°C) and 2 of nivalenol (340 and 499 mg/kg at 20 °C).     

Ultrastructural changes in isolated plastids

Summary Etio-chloroplasts were isolated from greening maize leaves and their ultrastructure was investigated immediately after isolation, as well as at intervals of several hours after their exposure to light or darkness. The following ultrastructural changes have been observed:In plastids isolated from etiolated leaves illuminated for 1–2 hours, the crystalline structure of the prolamellar bodies is partly restored during the isolation. In some plastids, regions with a regular, crystalline structure of densely packed tubules are even observed. The prolamellar bodies do not change further, either in light or in darkness.In young chloroplasts—i.e., in plastids isolated from etiolated leaves, illuminated for 6 or 15 hours—many prolamellar bodies, usually lying between the grana, appearde novo during isolation. These prolamellar bodies do not disappear in light either. They do not develop at all, however, if the isolation is performed at low temperature (4 °C).The results of the present paper indicate that in isolated etio-chloroplasts some tubular structures are newly formed, but that the conversion of this material into the thylakoids is not possible under the experimental conditions used.     

Ahemeral light regimens test the photoperiodic threshold of the european starling(Sturnus vulgaris)

Male European starlings(Sturnus vulgaris) were held for three consecutive photoperiod oscillations (ahemeral years) composed of 30-h day lengths, i.e., the daily light and dark each lasted three hours longer than under the natural daily photoperiod at latitude 38°N. These starlings had no gonad metamorphosis during the 45 actual months necessary to complete the three ahemeral photoperiod oscillations; nor did subsequent exposure to continuous illumination elicit gonad response. It is concluded that the daily duration of light and darkness (although certainly operant in controlling starling sexual cycles under temperate-zone photoperiod oscillations) is not the critical factor establishing a sexual cycle under the ahemeral regimen. Rather, it appears that this species must experience a daily duration of light of 12 hours or less (a definitive photoperiodic threshold) before photo-induction of a sexual cycle is possible.Presented at the Eighth International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.     

Coupled saccharification and fermentation of pre-treated Eucalyptus wood: a simple kinetic model

Coupled saccharification and fermentation of Eucalyptus globulus wood, pre-treated by acid hydrolysis and sodium hypochlorite, was carried out in two column reactors: one for enzymatic hydrolysis of the substrate at 50°C and the other for fermentation of sugars with calcium alginate-immobilized Saccharomyces cerevisiae at 30°C. A buffered solution containing cellulases at pH 4.8 was recycled through both reactors. The maximum yields were about 0.26 g ethanol per g of substrate. The results were reproduced reasonably well using a simple kinetic model consisting of two successive pseudo-first-order reactions.C. Albornoz and D. M. Ferrari are with the Centro de Investigaciones Tecnológicas (CIT), Administración Nacional de Combustibles, Alcohol y Portland (ANCAP), Pando, Canelones, C.P. 91000, Uruguay. S. Blanco and G. Ellenrieder are with Instituto de Investigaciones para la Industria Química (INIQUI), Universidad Nacional de Salta (UNSa), Buenos Aires 177, 4400 Salta, Argentina.     

Ultrastructure of neurosecretory cells of the hypothalamic supraoptic nucleus in white rats following painful stress and during aging

The ultrastructural organization of neurosecretory cells (NSC) belonging to the hypothalamic supraoptic nucleus was investigated in young rats following periods of painful stress differing in duration (of 2 and 20 min). Intact young rats of similar age and others at late stages of development (24–27 months old) served as controls. Short- and longer-acting painful stress was found to intensify and inhibit the functional activity of NSC respectively. Complex ultrastructural changes in the NSC of young rats following protracted painful stress is compared with the ultrastructural organizational pattern in several NSC of aging rats. Findings would imply that aging occurs in rats following prolonged painful stress, resulting from functional hypersecretion and depletion.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 21, No. 3, pp. 389–395, May–June, 1989.     

Energization and ultrastructural pattern of thylakoids formed under periodic illumination followed by continuous light

Bean leaves grown under periodic illumination (56 cycles of 2 min light and 98 min darkness) were subsequently exposed to continuous illumination, and in connection with granum formation and accumulation of the light-harvesting pigment-protein complex thermoluminescence and light-induced shrinkage of thylakoid membranes were studied. Juvenile chloroplasts with large double sheets of thylakoids obtained under periodic light exhibited low temperature spectra of polarized fluorescence yielding fluorescence polarization (FP) values < 1 at 695 nm, characteristic for pheophytin emission. In the course of maturation under continuous light when normal grana appeared and the chlorophyll a/b light-harvesting photosystem II complex was incorporated into the membrane, at 695 nm the relative intensity of fluorescence dropped and FP changed to a value of > 1, suggesting an overlap between the emission of pheophytin and that of the chlorophyll a/b light-harvesting photosystem II complex. Thermoluminescence glow curves recorded with juvenile thylakoids displayed a relatively high proportion of emission at low temperatures (around -10°C) while with mature chloroplasts, more thermoluminescence originated from energetically deeper traps (discharged around 28°C). This means that during thylakoid development the capacity of the membrane to stabilize the separated charges increases, which might be favourable for the ultimate conservation of energy. The more extensive energization of mature thylakoids was also indicated by a light-induced decrease in the thickness of the membranes upon illumination; a change which could not be detected in juvenile thylakoids.Abbreviations EDTA ethylenediamine tetraacetic acid - Hepes 4-(2-hydroxy ethyl)-1-piperazine ethane sulfonic acid Dedicated to Prof. L.N.M. Duysens on the occasion of his retirement.     

Orientation responses of Triops granarius (Lucas) (Branchiopoda: Notostraca) and Streptocephalus ssp. (Branchiopoda: Anostraca)

Summary Triops granarius and Streptocephalus spp. show an orthokinetic response and swim faster in light than in darkness. Triops is negatively, Streptocephalus positively phototactic. The lethal temperature for 24 hours' exposure is 34°C for Triops, 35°C for Streptocephalus. Temperatures around 29°–30°C are preferred by both to 20°C or 33°C. Phototaxis overrides these temperature reactions in Streptocephalus but not in Triops. Both swim against water currents: Triops does not become habituated to mechanical stimuli upon responses to which its survival may depend.

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Résumé Le Triops granarius et le Streptocephalus spp. ont une réaction orthocinétique et se déplacent plus vite dans la lumière que dans le noir. Le Triops est négativement phototactique, le Streptocephalus l'est positivement. La température mortelle pour une exposition de 24 h. est 34°C pour le Triops et 35°C pour le Streptocephalus. Tous les deux préfèrent des températures de l'ordre de 29°–30°C plutôt que de 20°C ou 33°C. Le phototactisme domine ces réactions aux température chez le Streptocephalus mais pas chez le Triops. Tous les deux se déplacent contre les courants: le Triops ne peut pas s'accoutumer aux excitents méchaniques, même si sa vie dépend de sa réaction à ces excitents.