Scaling of enzyme activity in larval herring and plaice: effects of temperature and individual growth rate on aerobic and anaerobic capacity

Herring Clupea harengus and plaice Pleuronectes platessa were reared at 8 and 12° C from the fertilized egg to a larval age of up to 600 degree-days. Soluble protein as well as the activities of both citrate synthetase (CS) and lactate dehydrogenase (LDH) were measured in homogenate supernatants of individual larvae at 10° C. Scaling factors were calculated using the expression y = ax^b where y is the enzyme activity, x the protein content of the larva a is a constant and b the scaling factor. All scaling factors showed significant differences between the species. Within species, the scaling factors for CS activity were either small or not significantly different between the two rearing temperatures, but the scaling factors for the LDH activities were significantly different at the two temperatures for both species. Herring larvae, which had higher LDH activities when newly hatched, showed smaller scaling factors for LDH ( b =1·42 at 8°C and b =1·07 at 12° C) than plaice ( b =2·11 at 8°C and b =1·45 at 12° C). Activities converged as the larvae grew. The results of the current study together with reanalysis of data from the literature indicate an increasing aerobic and anaerobic capacity during the larval stage of fishes (positive allometry).     

Early development of the skull of Sander lucioperca (L.) (Teleostei: Percidae) relating to growth and mortality

The early osteological development of the skull (chondrocranium and osteocranium) of the pikeperch Sander lucioperca was studied. Specimens were reared at two temperatures, 15·5 and 18·0° C, from hatching until 47 and 43 days after fertilization (DAF), respectively. The skeletal elements characteristic for the different developmental stages were the same at both rearing temperatures, but pikeperch reared at 15·5° C reached the developmental stages later. The formation of the functional complexes, the neurocranium, jaws and suspensorium, branchial basket and hyoid arch, was evaluated chronologically. The focus was on skull development during several functional changes: at hatching, at the shift from endogenous to mixed feeding, the shift to exclusively exogenous feeding and upon reaching the final prey-capture mechanism. Growth in total length differed between fishes reared at the two temperatures, except during a phase of very slow growth from the end of the embryonic stage until the second larval stage. The latter phase, in which most of the bony elements of the viscerocranium started to form, was marked by high mortality. When exogenous feeding began, the growth rates at both temperatures increased distinctly and the first bony elements were formed in the neurocranium. Specimens reared at 18·0° C grew continuously, but those at 15·5° C showed a second period of slow growth and high mortality. Fish reared at 18·0° C reached the successive larval stages distinctly earlier than fish reared at 15·5° C.     

The cell kinetics of teleost fish epidermis: Epidermal mitotic activity in relation to wound healing at varying temperatures in plaice (Pleuronectes platessa)

An autoradiographic study of experimental wounding of the skin of juvenile plaice was performed using tritiated thymidine (20 μCi per gram body weight) injected intraperitoneally, at water temperatures of 5, 10 and 15°C.
Samples of lesion were taken at regular intervals up to 108 hours and autoradiographic preparations made. In addition wounds of less than 12 hours duration, unsuitable for autoradiography were examined and in vitro explant autoradiography studies on similar material used to support the findings for these short term lesions. Results showed that there was a very rapid migration of Malpighian cells into the defect which was not accompanied by any evidence, over the time-scale of the study, of a mitotic burst. Adjacent normal skin was markedly reduced in thickness. Closure of these relatively small wounds was achieved within nine hours at 10°C and by 12 hours at 5°C. The thickness of the migrated epidermal cover was much thicker at 15°C than 5°C.
Numbers of labelled cells were similar in migrating and peripheral epidermis and mucous cells appeared to be randomly distributed except in the periphery of advancing migrating cells, where thev were absent.     

Effects of temperature on developmental performance, survival and growth of sea lamprey embryos

This study assesses the influence of thermal regime on the development, survival rates and early growth of embryos of sea lamprey Petromyzon marinus incubated at five constant temperatures (7, 11, 15, 19 and 23° C). The time from fertilization to 50% hatching and from hatching to 50% burrowing were inversely related to incubation temperature. All the embryos incubated at 7° C died at very early stages, while those maintained at 11° C did not attain the burrowing stage. Survival from fertilization to hatching was 61, 89, 91 and 89% at 11, 15, 19 and 23° C, decreasing to 58, 70 and 70% from hatching to burrowing at 15, 19 and 23° C, respectively. Larvae reared during the first 3 months of exogenous feeding in a common environment at constant 21° C, revealed maximum survival for an incubation temperature of 15° C (43% of burrowed larvae) decreasing strongly at 19° C (16%) and 23° C (one suvivor among 240 larvae). Body length at the burrowing stage was maximum for embryos incubated at 19° C, but body mass increased in the interval 15–23° C. Mean incubation temperatures experienced by 117 broods during the embryonic development in the source river were estimated in 15·3±2·30° C and 16·7±1·76° C (mean±1 s.d .) for the periods fertilization-to-hatching and hatching-to burrowing, respectively.     

Discovery and initial characterization of a new conditional (temperature-sensitive) maternal effect mutation in the axolotl

Abstract. The discovery of a new temperature-sensitive maternal effect mutation in Ambystoma mexicanum is described. The new gene ( ts-1 ) was recognized when 100% of the eggs spawned by homozygous females failed to develop past early gastrulation when reared at 25° C. Eggs raised at 10° C developed normally to sexual maturity. A temperature-sensitive period during blastulation was identified by a preliminary series of temperature shifts. Histologic examination revealed that nuclear abnormalities, especially chromosomal bridges, characterized ts-1 embryos reared beyond the ninth cleavage at the restrictive temperature (25° C).     

The effect of pre-fasting diet and water temperature on liver glycogen and liver weight in rainbow trout, Salmo gairdneri Richardson, during fasting

The effect of feeding an isocaloric and isonitrogenous trout diet that contained different levels of digestible carbohydrate (cerelose) to rainbow trout at either 10 or 15° C on liver glycogen and liver weight was determined in two fasting studies of 12 and 41 days duration. Trout fed diets with increased levels of digestible carbohydrate (HC) had significantly higher liver-body weight ratios (LW) and liver glycogen (LG) than trout reared on low digestible carbohydrate diets (HF). Both LW and LG declined in fasting trout previously fed HC diets but declined little in fasting trout previously fed HF diets. Trout reared at 10° C had higher LW and LG than trout reared at 15° C on either the HC or HF diets. During fasting, the trout reared on HC diets at 10° C required a longer period of time for the LG and LW to decline to the levels of trout reared on the low carbohydrate diets, than did trout reared on the HC diets at 15° C. The results indicate that both pre-fasting diet and water temperature can affect liver glycogen utilization and liver weight in fasting trout. Prolonged elevation of LW and LG in fasting trout could jeopardize the survival rate of stocked trout, particularly at low water temperatures.     

Photomicrographic atlas of Atlantic herring embryonic development

The development of the Atlantic herring is related to a staging series intended to provide a standard background for studies of herring embryonic development. The series is based on herring embryos from the Isle of Man (Irish Sea) stock reared at 8°C. The stages are named rather than numbered in order to simplify usage and the series has been sub-divided into five periods: zygote and cleavage, blastula, gastrula, segmentation, and organogenesis.     

Effect of temperature and host stage on performance of Aphelinus varipes Förster (Hym., Aphelinidae) parasitizing the cotton aphid, Aphis gossypii Glover (Hom., Aphididae)

Development time, mummification, pupal mortality, host feeding and sex ratio of a Norwegian strain of Aphelinus varipes Förster parasitizing the cotton aphid, Aphis gossypii Glover were studied at 20, 25 and 30°C in controlled climate cabinets. Petri dishes with cucumber ( Cucumis sativus L) leaves on agar were used as experimental units. Cotton aphids in different larval instars and as adults, reared at the three different temperatures, were presented to A. varipes in a `no-choice' situation for 6 h. These presentations were done at 25°C in each experiment to avoid an influence of temperature on parasitization rate. More first instar aphids were parasitized than third and fourth instars among the aphids reared at 20°C. Pupal mortality of the parasitoid was not influenced by temperature. It was lower in aphids parasitized as adults than in aphids parasitized in second instar. The sex ratio of A. varipes was female-biased, and varied between 92% females developed from aphids reared at 25°C and 70% from aphids reared at 20°C. The sex ratio was not significantly influenced by host stage. The development time of A. varipes ranged from 17.5 days at 20°C to 9.8 days at 30°C.     

Temperature-dependent genotypic selection and embryonic survival of rainbow trout

The survival of rainbow trout (Salmo gairdneri) with different developmental rates and genotypes at eight polymorphic loci was compared in two experiments. The embryos were reared at temperatures colder (5 and 8°C) and warmer (12°C) than normally experienced by the strain (9.5°C). Embryo survival in five different hatching groups (representing the sequential order of hatching) was compared at 8 and 12°C. Embryos in the center of the hatching distribution (groups 2, 3, and 4) showed a greater survival to yolk sac resorption than those in the extremes (groups 1 and 5). These differences are significant in the embryos reared at 12°C in both experiments. Embryo survival from hatching to yolk sac resorption was poorer at 12 compared to 8°C. In the one experiment where it was examined, significantly fewer embryos hatched at 5 and 12 than at 8°C. Significant deviations from genotypic expectations (based upon parental allele frequencies) were detected in the progeny (23 of 34 cases). In contrast, few deviations from Hardy-Weinberg expectations were detected (5 of 34 cases) when progeny allele frequencies are used. Few significant differences in genotype frequencies were detected among the progeny reared at the different temperatures. This suggests that nonequal contributions of parental gametes rather than differential selection of genotypes account for the deviations from expectations in the progeny.This research was supported by National Science Foundation Grant BSR-8300039 awarded to Dr. Fred W. Allendorf. Moira M. Ferguson was supported by a postgraduate scholarship from the Natural Sciences and Engineering Research Council of Canada.     

Effects of different incubation temperatures on the yolk‐feeding stage of Eupallasella percnurus(Pallas)

Embryos and yolk‐feeding larvae of lake minnow Eupallasella percnurus were reared at 13, 16, 19, 22 and 25° C with no access to external food. Time from egg activation to first embryonic movements, hatching, filling of swimbladder and final yolk resorption increased with decreasing temperature. At 13° C, c . 40% of larvae were unable to fill their swimbladder. The predicted lower temperature at which development and growth ceased (biological zero, t ₀) was the same for both processes, c . 7·5–10·5° C. There was no ontogenetic shift in the t ₀ value. Temperature coefficients for development ( Q _10dev.) ranged from 2 to 3 at 19–25° C, but were higher in hatched larvae at lower temperatures. Eggs of E. percnurus had a combination of small size, high hydration and low caloric value of fresh matter. Dry mass of larval tissue on yolk, percentage of dry matter in wet matter, and specific growth rate were maximized at 22 and 25° C. At 19–25° C, energy and matter contained in the initial eggs were converted to body tissue most efficiently. Temperatures from 22 to 25° C are considered optimal for E. percnurus embryos and yolk‐feeding larvae and are recommended for their indoor rearing.     

Diapause in a Glasgow strain of the flour moth, Ephestia kuehniella

ABSTRACT. The incidence of diapause in Ephestia kuehniella Zeller from an unhealed granary in Scotland was influenced by both photoperiod and temperature. At 25°C, nearly 50% of larvae entered diapause when reared in continuous darkness (DD) and up to 30% did so in short photoperiods. Little diapause was detected around LD 14:10 but a second, smaller peak of about 20% occurred at LD 16:8 and LD 18:6, falling away again to nearly zero in continuous light. More larvae entered diapause when reared continuously at 15 or 20°C than at 25 and 30°C. However, when larvae reared from hatch at 25°C in LD 16:8 were transferred after 1 week to 15°C in LD 9:15, almost twice as many entered diapause as did those reared at 15°C throughout. The sensitive phase for diapause induction occurred near the start of the final instar. The mean duration of diapause was between 2 and 3 months in most photoperiods at 20 and 25°C, and was shorter at 15°C. However, in DD at 25°C, it lasted about 7 months. Termination of diapause was hastened in larvae reared at 25°C in DD by transferring them to LD 14:10, and also by chilling them at 7.5°C for 6 weeks before returning to 25°C in DD. In an unhealed store in southern England, viable adults emerged from May to July and originated from larvae which terminated diapause relatively late. It would appear from the results of transferring larvae back to the laboratory at various times during the winter that some phases of diapause development were completed quite early after exposure to low temperatures, although no further development took place in the store until temperatures rose again in April.     

Opposite effects of temperature on breaking of dormancy and on induction of frost resistance in apple embryos

Apples ( Pyrus mains L., ev. Golden Delicious) were placed at 0, 12 and 35°C. At different intervals, seeds were taken from fruits, and the ability of isolated embryos to germinate was determined. In parallel, the survival of similar embryos frozen for 30 min at -7°C was estimated. Storage of apples at 0°C led to complete removal of embryo dormancy within ca 10 weeks. At 12°C, dormancy was only partly eliminated, and at 35°C breaking of dormancy did not occur. The onset of secondary embryo dormancy was thus evident as the result of 35 and 12°C treatments. On the other hand, the storage of apples at 35°C was the most effective treatment for induction of frost resistance in the embryos. At 12°C the same level of frost resistance was reached much slower. Even a prolonged storage of apples at 0°C did not allow frost survival of all embryos. The above relations were confirmed in experiments with transfer of fruits from one temperature of storage to another. The temperature of fruit storage affected the dormancy removal in embryos and induction of resistance to rapid freezing in opposite directions.     

Induction of developmental abnormalities in larval goldfish, Carassius auratus L., under cool incubation conditions

Compared with incubation at a constant 22° C, exposure of goldfish embryos and larvae to 13° C, under a variety of thermal protocols, caused increased frequencies of abnormal development and, in some cases, reduced survival to hatching. The low-temperature incubation conditions were particularly deleterious when eggs were incubated at 13° C from the outset, regardless of the temperature at which the donor female ovulated and the eggs were fertilized. Significantly higher frequencies of developmental abnormalities were also noted when embryos were transferred from 22°C to 13°C at 6, 24, 128 and, in one case, 175 h after fertilization. In three of five experiments, subjecting embryos and larvae to diel fluctuations between 22 and 13° C, with a 5-h hold at the lower temperature, caused an increase in development abnormalities. These results demonstrate that the thermal requirements of goldfish embryos and larvae necessitate a delay in ovulation and spawning until water is sufficiently warm. Developmental abnormalities can be induced by exposure to cool (13° C) conditions, at least up to the time that swimbladder inflation occurs.     

Implications of Chaoborus pupation and ecdysis in cold water

1. Cold water acted differently to delay and lengthen the pupation period for the larvae of two species of the zooplankton predator Chaoborus (Diptera: Chaoboridae). During Chaoborus pupation, the zooplankton community is released from predation, while the dark-coloured Chaoborus pupae are more susceptible to their own predators.
2. Fourth instar larvae of Chaoborus americanus and C. trivittatus , collected from an oligotrophic lake, were reared individually at 5 °C in the dark. Chaoborus americanus was also reared at 9 and 12 °C under spring photoperiod conditions (L : D, 16 : 8 h). Individuals were observed through pupation to emergence (ecdysis) or death.
3.  Chaoborus americanus pupated at 5, 9 and 12 °C with substantial emergence only at 12 °C. In comparison, C. trivittatus emerged at 5 °C. Light was not a necessary cue for pupation and ecdysis, contrary to previous reports. Cold water delayed the onset and lengthened and increased the variability of the duration of pupation.
4. In Shirley Lake, C. americanus pupated in late June–early July while C. trivittatus pupated first in April and again in June–July.
5.  Chaoborus americanus pupae needed a temperature cue to complete ecdysis. The ecdysis temperature threshold helps to explain the difference in pupation timing, and the geographical distribution, of C. americanus and its relatively inflexible life history contrasted with C. trivittatus . Delayed predator pupation in years with low spring temperature can affect the community dynamics of the prey.     

Effects of photoperiod and temperature on the development and diapause of the bark beetle Ips typographus

Abstract:  Diapause was induced in a Central European population of Ips typographus grown at 20°C when the day length decreased below 16 h [50% diapause incidence occurred in the 14.7:9.3 h L:D (light:dark) regime]. The non-diapausing adults fed on days 2–6 and 10–14 after the ecdysis and swarmed after the second feeding bout with chorionated eggs in the ovaries and sperm in the spermiducts. Neither gonads nor the flight muscles matured and no swarming occurred in the diapausing adults. The development from egg to adult took about 34 days in both 18:6 h (no diapause) and 12:12 h L:D (diapause) regimes, but it was extended by up to 30% without diapause induction when only larvae or pupae were exposed to L:D 12:12 h. Diapause was induced in insects reared at L:D 12:12 h through the last larval and the pupal instars and/or in the adult stage. Temperature ≥ 23°C prevented diapause induction at L:D 12:12 h but diapause occurred at L:D 14:10 h associated with 26:6°C thermoperiod. The effect of thermoperiods on the developmental rate requires further research. Exposure of the non-diapausing adults to 5°C for several days blocked feeding and evoked a diapause-like state, whereas diapausing adults fed and their gonads slowly developed at this temperature. Diapausing adults exposed in forest to low night temperatures and transferred in October to 20°C readily reproduced at 18:6, but not 12:12 h L:D photoperiods. After 2-months at 5°C and darkness, they became insensitive to the photoperiod, matured and most of them also swarmed at 20°C in the 12:12 h L:D regime. In a Scandinavian population, diapause occurred at 18:6 h L:D and was terminated either by exposure to 5°C or by very long photoperiod (L:D 20:4 h) combined with high temperature (23°C).     

Effects of temperature, sorbitol, alanine and diapause hormone on the embryonic development in Bombyx mori: in vitro tests of old hypotheses

Abstract.  An in vitro culture method is described in which embryonic development in Bombyx mori is traced at various temperatures and treatments. The results show that the induction, intensification and termination of diapause are distinct processes. Prediapause embryos, explanted from 40-h-old diapause-destined eggs and cultured in Grace's medium, continue to develop to the appendage-formation stage without arrest, which indicates that the isolated embryos have not entered diapause, whereas the development of embryos from diapausing eggs (15 days after being laid) is significantly slower. The rate of development of embryos dissected from diapause eggs increases during chilling (5 °C) and incubation (at 25 °C) gradually during chilling and dramatically at 25 °C. The in vitro experiments also reveal that sorbitol directly inhibits the development of embryos explanted from diapausing eggs but has no affect on the development of embryos from prediapause eggs. Neither alanine nor diapause hormone prevent isolated embryos from developing.     

Effects of ambient colour on colour preference and growth of juvenile rainbow trout Oncorhynchus mykiss (Walbaum)

Colour preference of individual juvenile rainbow trout Oncorhynchus mykiss was tested at 1 and 12° C, and also at 12° C after a 42 day growth experiment under white, blue, green, yellow or red ambient colour. All experiments were carried out under controlled laboratory conditions and the preference was assessed by the location of the fish in a preference tank with four chambers. Rainbow trout showed a preference for blue and green at 1° C and for green at 12° C. After the growth experiment the fish reared in blue tanks preferred blue and green but green was the most preferred colour for the fish reared in green, yellow and red tanks. Yellow and especially red chambers were avoided, irrespective of the ambient colour during the growth trial. The final mass of fish reared in the red aquaria was significantly smaller than that of the fish in green tanks. In addition, when the data of the preference tests were correlated with the data of the growth experiment using mean values of the four tested colours, a very good linear relationship was observed between the preference ( i.e. visit frequency in coloured compartments) and growth rate as well as food intake. When considering the results both from the preference and growth trials it is suggested that green is the best environmental colour for rearing juvenile rainbow trout while rearing in a red environment cannot be recommended.     

Influence of photoperiod on low temperature acclimation for cold-hardiness in Drosophila auraria

ABSTRACT. Imagines of Drosophila auraria Peng, a reproductive diapause species, developed cold-hardiness at low temperatures to a greater extent when exposed to a diapause-inducing photoperiod (LD10:14 h) than when exposed to a diapause-preventing photoperiod (LD 16:8h). Imagines kept at 18°C, which was the temperature at which they were reared to eclosion, did not survive a test exposure to -5°C for 8 days regardless of age or photoperiod. When transferred to 10 or 5°C, either from eclosion or from 8 days after eclosion, the survival rate, on testing, rose with time since transfer and rose faster and higher with a photoperiod of LD 10:14h than with LD16:8h. Flies transferred to 15°C only showed improved ability to survive the test if they were kept in LD 10:14h. When cultured at 18°C to the age of 8 days after eclosion, diapause was terminated in about 30% of females even at LD 10:14h. In these post-diapause females the ability to develop cold-hardiness at lower temperatures was somewhat less than in the diapausing females, but apparently greater than in the non-diapause females. These results suggest that the physiological mechanism which promotes cold-hardiness under a diapause-inducing photoperiod is not directly linked to the process causing reproductive diapause.
In Sapporo, flies from a natural population became tolerant to cold in October when they entered diapause and daily mean temperature fell below 15°C and the light/dark cycle fell below LD 12:12h.     

Influence of food quality and temperature on life history characteristics of the parthenogenetic mayfly, Cloeon triangulifer

SUMMARY. 1. Laboratory and field data indicate that Cloeon triangulifer McDunnough has at least three generations per year in White Clay Creek (Pennsylvania, U.S.A.).
2. The duration of the egg stage ranged from 5 days at 30°C to about 90 days at 10°C.
3. Larvae completed development (i.e. first instar to adult) in 27 days at 25°C, 45 days at 20°C, and 179 days at 10°C on an algal diet dominated by diatoms.
4. Larvae reared on hickory leaves completed development in 30 days at 25°C but died prior to metamorphosis at 10, 15 and 20°C.
5. Adult size (i.e. body length, wing length and dry mass) and fecundity were inversely related to rearing temperature for all laboratory and field experiments.
6. The significant interaction of food quality and temperature suggest that these factors may be important in understanding geographic variation in the life history of C. triangulifer.