Sublethal effects of three ectoparasites on fish

Vulnerability to predation, resistance to high temperature, weight-length relationships, and fecundity were compared for fish with and without or with light and heavy infestations of three ectoparasites. The fish and parasites were fathead minnow ( Pimephales promelas ) with anchor worm ( Lernaea cyprinaceae); brook trout ( Salvelinus fontinalis ) with gill lice ( Salmincola edwardsii); and yellow perch ( Perca flavescens ) with black-spot ( Neascus of Crassiphiala bulboglossa). The only sublethal effect found was that of gill lice, which reduced resistance of brook trout to high temperature. None of the three ectoparasites increased vulnerability offish to predation by piscivorous fish.     

Gap junctions in the differentiated neural retinae of newly hatched chickens.

Gap junctions in the neural retinae of newly hatched chickens were examined in thin section and by freeze cleaving. Unusual gap junctions containing linear arrays of intramembrane particles are found between principal and accessory cones which form a double cone at the region of the outer limiting membrane. These unusual gap junctions are often continuous with macular aggregates of hexagonally packed intramembrane particles which are characteristic of a typical gap junction. Typical gap junctions are also found in both the outer and the inner plexiform layers and in the outer nuclear layer, but are not so abundant as in the outer limiting membrane region. The sizes of intramembrane particles and their centre-to-centre spacing within the macular aggregate of a gap junction in differentiated neural retinae are slightly larger than those in undifferentiated neural retinae. Tight junctions are not found in differentiated neural retinae.     

Induction of microsomal stearyl coenzyme A desaturase in the newly hatched chicks.

The development of the stearyl-CoA desaturase system was studied in newly hatched chicks. The desaturation activity was very low in hepatic microsomes from chick embryos, less than 0.05 nmol of oleate formed min^?1 (mg of protein)^?1. After hatching and feeding, the desaturation activity gradually increased to 4–5 nmol of oleate formed min^?1 (mg of protein)^?1 in 6-day-old chicks. This increase could be prevented by administration of cycloheximide or actinomycin D. Measurement of the microsomal electron transfer components throughout the induction period showed no significant changes in the NADH- or NADPH-specific reductases or in the concentrations of cytochromes b₅ and P-450. However, the activity of the terminal component of the desaturase system (the desaturase enzyme) increased in parallel with the desaturation activity. Supplementing the liver microsomes from chick embryos with isolated desaturase enzyme resulted in the formation of an active desaturation system. It is proposed that the induction of the stearyl-CoA desaturase system during development of newly hatched chicks is dependent on the synthesis of the terminal desaturase enzyme.     

Tissue-Specific antioxidant profiles and susceptibility to lipid peroxidation of the newly hatched chick

The hatching process is characterized by a range of adaptive changes, and a newly hatched chick is considered as an intermediate stage between prenatal and postnatal development. The aim of the present study was to evaluate the characteristic relationships between tissue-specific fatty acid composition and antioxidant protection in newly hatched chicks. Liver, yolk sac membrane, heart, kidney, lung, and four brain regions (cerebrum, cerebellum, stem, and optic lobes) were collected. Fatty acid composition of total lipids and phosphoglycerides, α-tocopherol, lutein, ascorbic acid, reduced glutathione, and the activities of Mn-and Cu,Zn-superoxide dismutase (SOD) and Se-dependent and non-Se-glutathione peroxidase (GSH-Px), and catalase (CAT) were determined. The levels of Fe, Cu, Zn, and Mn as well as tissue susceptibility to lipid peroxidation were also studied. The tissues of the newly hatched chick showed distinctive features in fatty acid profiles, antioxidant accumulation, and susceptibility to lipid peroxidation. The brain clearly displayed the greatest susceptibility to spontaneous and Fe-stimulated lipid peroxidation, was highly unsaturated and contained very low levels of vitamin E, no detectable carotenoids, low GSH-Px, and low CAT activity. At the same time, the brain was characterized by high ascorbic acid concentration and comparatively high SOD activity. It was suggested that in postnatal development, antioxidant enzymes presumably play the major role in antioxidant protection of the chick tissues.     

Modification of responses of newly hatched snails by exposure to odors during development

Predatory marine snail larvae and embryos were exposed to preyodors (oyster, mussel and barnacle) during development. Whenjuvenile snails hatched they were tested by bioassay to determineeffects of this prior odor exposure. Juvenile snails were testedwith oyster, mussel and barnacle odors and with partially purifiedbarnacle odor of known attractiveness. Independent of priorodor exposure, only solutions containing barnacle odor wereattractive. Snails exposed during development to prey odorsnot in themselves attractive were more responsive to barnacleodors than snails that developed in barnacle odors. Snails notexposed to prey odors during development were intermediate intheir responsiveness. Field bioassays showed detectable attractantlevels in an environment containing barnacles. Attractant activitywas not detected in an environment where barnacles were absent.Responses of snails that developed in field odor conditionswere similar to those of snails that developed in the presenceof barnacles. Odor exposure during development is importantin determining future responses of these predatory snails toprey odors. ¹Duke University Marine Laboratory, Pivers Island, Beaufort,NC 28516, USA²University of Miami RSMAS/MAC 4600 Rickenbacker Causeway, Miami,FL 33149, USA³Suffolk University, Department of Biology, Beacon Hill, Boston,MA 02114, USA     

Embryonic development and newly hatched larvae of the little dragon sculpinBlepsias cirrhosus

This paper describes both embryonic development and newly hatched larval morphology of the little dragon sculpinBlepsias cirrhosus. The eggs ofB. cirrhosus are almost spherical, 3.0–3.2 mm in diameter, and have a yolk color of burnt orange. Development is very slow, being especially sluggish once the embryo appears. The embryo begins forming from the 10th day. In size, the early embryo is less than 1/6 of the yolk’s circumference. Incubation at 10°C takes about 200 days, 50 days shorter than the incubation period in a natural environment, with a mean water temperature of 11°C. The notochord length of newly-hatched larvae averages 11.1 mm. The larvae are developed so fully that the notochord is already flexing and the caudal and pectoral rays are forming.     

Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis and Oestrus ovis

Abstract. Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis De Geer (Diptera: Gasterophilidae) and Oestrus ovis (L.) were studied by scanning electron microscopy. Two types of trichoid sensilla, two types of coeloconic sensilla and a pit sensillum were present on the thoracic and abdominal segments of G. intestinalis larvae. Sensilla on larvae of O. ovis were similar although only one type of trichoid sensillum was present. Total number of sensilla were higher for O. ovis than for G. intestinalis (248 v . 214). Variation in numbers of sensilla is consistent with the concept that increasing numbers of sensilla are associated with increasingly complex searching behaviour required to locate suitable habitats for development.     

Behavioral responses of newly hatched zebrafish (Danio rerio) to amino acid chemostimulants

The zebrafish chemosensory systems of olfaction, taste and solitary chemosensory cells (SCCs) are established during the first week after fertilization (a.f.). These systems presumably support the early development of feeding behaviors required as yolk supplies diminish over the same period. Yet there is no previous data reporting early chemosensory responses in zebrafish. We therefore assayed the chemosensory behavior of newly hatched zebrafish on days 3, 4 and 5 a.f. Responses were compared between fish exposed to water alone versus water containing a mixture of 12 amino acids (100 microM each) flowing through a 50 ml test chamber at 4 ml/min; computer-assisted motion analysis was used to quantify responses. Behavioral responses were first observed at day 4 a.f.; the number of fish swimming, their swimming speeds, and their net-to-gross displacement (NGDR) all increased significantly in response to amino acid stimulation. Because taste buds first appear 4-5 days a.f. and the SCCs may not respond to amino acids, these initial chemosensory responses of day 4 fish may be mediated by already established olfactory neurons. The onset of chemosensitivity in day 4 fish corresponded with an easily recognizable developmental phenotype of inactive floating; day 3 fish were inactive and resting on the bottom while day 5 fish were active and moving through the water column. The ease of identifying responsive day 4 fish suggests these animals may be useful for characterizing odorant sensitivity or developmental plasticity or for screening for chemosensory mutations.     

The Golgi complex in the esophageal mucous glands of the newly hatched chick

The general morphology of the mucous gland cell and the nature of the secretory granule in esophageal glands of the newly hatched chick have been described. Lightly basophilic supporting cells, attached to secretory cells by desmosomes and containing tonofilaments, are located on the basal lamina. Electron microscopic studies showed a morphological polarity of the Golgi complex which suggests that mucous precursors are transported from other sites within the cell to the Golgi complex for further packaging into secretory granules. Finally, acid mucopolysaccharides (AMPS) were specifically stained using the Thorotrast technique and not detected in the rough endoplasmic reticulum, the transitional elements, or in the lamellae at the forming face of the Golgi complex. Conversely, AMPS are found in the vicinity of the mature face of the Golgi complex, and in the secretory granules. The acquisition of cytochemical reactivity for AMPS within the Golgi complex is discussed.     

Effect of epidermal papillomatosis on survival of the freshwater fish Rutilus rutilus

Epidermal papillomatosis occurs in several marine and freshwater fish species. Previously, papillomatosis has been shown to induce mortality in juvenile carp. We studied the effect of epidermal papillomatosis on the survival of adult male roach Rutilus rutilus by caging naturally diseased, marked (by us) fish in the field. Within the constraints of the experimental design, there was no difference in survival between healthy, slightly diseased and heavily diseased fish. Therefore, we conclude that the possible effect of epidermal papillomatosis on the mortality of wild roach is relatively minor.     

冷冻前后的低渗应激对小鼠孵化囊胚存活率的影响

The objective of this study to evaluate the effect of hypotonic stress on developmental potential of hatched blastocysts perivitrification. Hatched mouse blastocysts were vitrified in liquid nitrogen after equilibration in 10% or 20% GL for 5 min and in GFS40 for 30 sec respectively, the survival rates were 93%-97% after the frozen-thawed embryos were cultured in vitro for 24 h. There were no statistical difference between the frozen and the fresh group (P > 0.05). In order to evaluate effects of hypotonic stress on developmental abilities, fresh hatched mouse blastocysts were respectively exposed to 1.00 x, 0.50 x, 0.30 x, 0.25 x and 0.20 x PBS for 30 min, then cultured in mKRB for 24 h, the survival rates were 98%, 99%, 92%, 92% and 50% respectively. The rate in 0.20 X PBS group was significantly lower than in other groups (P < 0.01). When frozen-thawed embryos were directly treated with different osmotic solutions, the survival rates were 88%, 72%, 58%, 11% and 0 respectively in 1.00 x, 0.50 x, 0.30 x, 0.25 x and 0.20 x PBS group. The rate in 1.00 x PBS group was significantly higher than in other groups (P < 0.05). However, when frozen-thawed embryos were first cultured in vitro for 12 h, then exposed to 1.00 x, 0.50 x, 0.30 x, 0.25 x and 0.2 x PBS, the survival rates were 98%, 94%, 82%, 58% and 26% respectively. There was no statistical difference between 1.00 x and 0.50 x PBS group (P > 0.05). Although the rate in 0.30 x, 0.25 x and 0.20 x PBS group was significantly lower than in 1.00 x group(P < 0.01), it was significantly higher than in the same treatment group without in vitro culture(P < 0.05).     

Climbing by newly hatched larvae of the spotted stalk borer Chilo partellus to the top of sorghum plants

The biological impact of consumption and utilization of celery was examined for the generalist herbivore, Spodoptera exigua (Hübner). An analysis of leaves and petioles demonstrated that both plant parts contained high levels of water (>85%), but that leaves contained twice as much total organic nitrogen as petioles. Developmental and reproductive rates were significantly higher (P<0.01, t-test) for larvae fed on leaves. Penultimate and final instars consumed significantly more (P0.05, t-test) dry weight of plant material when fed petioles as opposed to leaves. Although growth rates were similar regardless of food source for penultimate instars, conversion of food to body weight was lower for larvae limited to petioles. In the final instar, both growth and conversion rates were lower for larvae fed petioles than for those given leaves. Thus, since larvae exhibit preferences for the nutritionally less suitable petioles during later larval stages, environmental factors other than nutrition must influence movement and distribution of S., exigua in celery.

---

Résumé L'impact biologique de la consommation et de l'utilisation du céleri a été examiné sur un herbivore généraliste Spodoptera exigua Hübner. Une analyse de feuilles et de pétioles montre que ces deux parties de la plante ont une haute teneur en eau (>85%), mais que les feuilles contiennent deux fois plus d'azote organique total que les pétioles. Les taux de développement et de reproduction on été significativement plus élevés (<0,01 test t) pour les chenilles nourries sur feuilles. Les 2 derniers stades ont consommé significativement plus (P<0,05 test t) de poids sec de matière végétale en s'alimentant sur pétioles qu'en s'alimentant sur feuilles. Bien que les taux de croissance aient été voisins quel que soit l'aliment pour les avant-derniers stades, la conversion d'aliment en poids de corps était inférieure pour les chenilles ne consommant que des pétioles. Au dernier stade, tant les taux de croissance que de conversion des chenilles élevées sur pétioles étaient inférieurs à ceux des chenilles élevées sur feuilles. Ainsi, puisque les chenilles présentent une préférence pour les pétioles moins nutritifs au dernier stade larvaire, des paramètres écologiques autres que l'alimentation doivent influencer les mouvements et la distribution de S. exigua sur céleri.

     

Variability in water temperature affects trait-mediated survival of a newly settled coral reef fish

As animals with complex life cycles metamorphose from one stage to the next, carry-over effects from earlier stages can affect future mortality. To examine the relationship between early life history traits and survival, seven monthly cohorts of newly-settled bluehead wrasse Thalassoma bifasciatum were collected immediately after settlement and over sequential 3-day periods. Otolith analysis was used to quantify mean larval and juvenile growth rates, pelagic larval duration (PLD), and settlement size and condition of different age classes to identify the traits most important for survival. Overall, survivors tended to have shorter PLDs, to settle at smaller sizes and higher condition levels, and to exhibit faster early juvenile growth. Water temperature contributed to among-cohort variability in traits as warmer water led to faster larval and juvenile growth and shorter PLDs. Trait-specific fitness functions demonstrated that temperature can influence fitness by changing the nature of selection on each trait. Estimates of selection intensity revealed that settlement condition contributed the most to variation in fitness across cohorts, followed by juvenile growth. Frequent loss of low settlement condition individuals and occasional loss of the very highest condition fish suggest that particularly high settlement condition during the warmest temperatures may be detrimental. Not only does the quality of settlers vary over time, but selective loss of individuals with particular phenotypic traits is not pervasive and can vary with environmental conditions such as temperature.     

Effect of free CO2 on survival rate of fish eggs

Vitality of phytophilic and pelagophilic fish eggs was studied as affected by solved CO2. It is established that small concentrations of free CO2 in water (5-10 mg/l) stimulate the vitality of phytophilic fish embryos and inhibit the vitality of pelagophilic fish embryos, which is explained by differences in ecology of their development.     

Gene expression pattern of glucose transporters in the skeletal muscles of newly hatched chicks

The gene expression pattern of the glucose transporters (GLUT1, GLUT3, GLUT8, and GLUT12) among pectoralis major and minor, biceps femoris, and sartorius muscles from newly hatched chicks was examined. GLUT1 mRNA level was higher in pectoralis major muscle than in the other muscles. Phosphorylated AKT level was also high in the same muscle, suggesting a relationship between AKT and GLUT1 expression.