Expression of regenerative capacity of caudal spinal cord during the larval development of Xenopus laevis.
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Animals↗
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[The larval development of Dipetalonema rugosicauda (syn. Wehrdlikmansia rugosicauda) in the tick Ixodes ricinus. I. Infection of ticks with microfilariae using artificial feeding techniques (author's transl)].
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Animals↗
Anthelmintic activities of fenbendazole against Nematodirus helvetianus in cattle: effect on egg production, embryogeny, and development of larval stages.
Calves experimentally infected with Nematodirus helvetianus were treated with a single dose of fenbendazole at the rate of 5 mg/kg of body weight. Fenbendazole was found to have an efficacy of 97.4% against adult N helvetianus. Additionally, eggs recovered 12 hours after calves were given the anthelmintic had fewer and frequently abnormal blastomeres. Fewer eggs were evident at 36 hours after treatment, and none was found at 72 hours or later. On the culturing of eggs from manure passed at 12 hours and later, almost no larval stages developed.
Animals↗
Parasites of domestic and wild animals in South Africa. IV. Helminths in sheep on irrigated pasture on the Transvall Highveld.
The seasonal incidence of helminth infestation in sheep on newly established irrigated pastures was determined by the slaughter of pairs of tracer lambs exposed for periods of approximately 33 days from October 1968--July 1970 and of sets of 3 lambs from March 1971--May 1973. It took several months for the infestation to become established on the pasture, but thereafter, of the various species present; Haemonchus contortus was most prevalent. In general, peak burdens of this species were recovered from January--May or June, while marked inhibition of larval development was evident from April--August. Ostertagia circumcinta usually occurred in increased numbers from April--October, and larval development was inhibited during July and August. Although the sizes of the burdens varied considerably from year to year, Trichostrongylus spp. were present mainly from April--August. Oesophagostomum columbianum, although present in the lambs slaughtered during the first 5 months of the survey, virtually disappeared until May 1971. After this it reappeared in small numbers in nearly all the sheep, reaching peak burdens during April and May 1972, and May 1973. Moniezia expansa were generally recovered from the lambs slaughtered from November--May.
Agriculture↗
Independent temporal expression of two N-substituted aminoacyl-tRNA hydrolases during the development of Artemia salina.
Encysted embryos of the crustacean Artemia salina contain an enzymatic activity which hydrolyzes N-acetylphenylalanyl-tRNA to N-acetylphenylalanine and tRNA. The enzyme apparently does not hydrolyze other free or N-substituted aminoacyl-tRNAs. The levels of this enzyme do not significantly change during embryonic and early larval development. In contrast, an unspecific hydrolase active on several N-substituted aminoacyl-tRNAs is practically absent in the encysted embryos and during embryogenesis and appears abruptly during larval development. The independent temporal expression of these two hydrolases during Artemia salina differentiation makes this organism siuitable for the study of the physiological role of these enzymes.
Animals↗
Normal and experimentally induced lysosomal activity in the larval fat body of Calliphora erythrocephala Meigen.
Acid phosphatase activity was demonstrated by EM-cytochemistry in 4 day old third instar larvae of the fly Calliphora erythrocephala Meigen, but not in younger stages. During larval development, the activity increased, reaching a maximum at the onset of pupariation. The reaction product was localized in Golgi vesicles and sacculi, in vacuoles and in protein granules of varying size and composition, confirming the autophagic character of the protein granules. Throughout larval development, the reaction product was restricted to membrane-bound structures and no indications of "free" cytoplasmic activity that might be related to cytolysis were found. Enzyme activity could be evoked by transplanting inactive fat body lobes into host larvae of a later developmental stage. High enzyme activity was induced in these transplants within 18 h. The sites of activity were roughly the same, but a portion of the activity in the transplants was found in the vacuoles. The induction could be inhibited by cyclohexamide.
Acid Phosphatase↗
A comparison of beating parameters in larval and post-larval locomotor systems of the lobster Homarus gammarus (L.).
A study has been made of the interrelations between rhythmical exopodite beating in different larval stages and swimmeret beating in poast-larval stages of the lobster Homarus gammarus. Data on exopodite beat cycle durations have been used for statistical comparisons of exopodite performance within one larva, and also between different stages of larval development. Inter-exopodite comparisons reveal clear bilateral differences (table 1), although there is no consistently favoured relationship (tables 2 and 3). There are significant differences in cycle duration between the first three developmental stages, with a slight increase at the first moult, and a marked decrease at the second (table 4). However, within each stage the repeat frequency exhibits little change (table 5). Therefore it appears that changes in swimming behaviour occur discontinuously in development, and are associated with the larval moults. It is suggested that changes in beat frequency, and especially the faster beating in stage III, may represent responses to changed loading conditions (table 7). Measurements of swimmeret beating in post-larval lobsters have been analysed in terms of cycle durations, and inter- and intra-segmental phase relations. Swimmeret beating patterns are very regular (figure 1), but not restricted to a narrow range of frequencies (table 6a). Intersegmental phase lag remains constant around 0.2 (figure 3) independent of beat frequency (figure 4). Similarly the powerstroke/returnstroke ratio of approximately 0.5 (figure 5) shows no significant correlation with cycle duration (figure 6). Differences emerge in the performance of larval exopodites and post-larval swimmerets (table 6b), although the possibility cannot be excluded that the larval exopodite oscillator in some way influences the developing action of the post-larval swimmeret system.
Age Factors↗
Development of the compound eyes of dragonflies (Odonata). II. Development of the larval compound eyes.
The development of the compound eye was analyzed by marking individual ommatidia and by studying naturally occurring pigment band patterns. New ommatidia are added to the eye along its anterior margin. This changes the directions of view of the older ommatidia with the greatest change occurring in the fovea. New ommatidia are added to the fovea medially, and old ones are removed laterally as their interommatidial angles and directions of view in the visual field change. Over one-third of the aeshnid ommatidia are foveal during at least one of the early larval instars, and are then used for peripheral vision later in development. The design of each ommatidium is a compromise so that it is adapted for all stages of development, but sometimes better adapted for one instar than for others. Factors which are balanced for best vision are lens diameter, facet admission function, interommatidial angle, and inclination of the optic axis to the eye surface. Ommatidia are described in terms of these factors throughout their life history, from initial differentiation anteriorly, through passage through the fovea, to their final relatively posterior location.
Animals↗
Development of Dipetalonema viteae third-stage larvae (Nematoda: Filarioidea) in micropore chambers implanted into jirds, hamsters, normal and immunized mice.
Development of third-stage larvae of Dipetalonema viteae within subcutaneously implanted micropore chambers proceeded in all hosts tested up to the fourth-stage larvae and occasionally to adolescent worms. In the jird the timing of development was comparable to a natural infection. Although the mouse is an insusceptible host, larval development could take place, but was very slow. Two intraperitoneal inoculations of living third-stage larvae into mice induced the production of antibodies against the larval cuticle and against common antigens. In such immune mice the development of third- and fourth-stage larvae within micropore chambers was significantly inhibited, larval mortality was increased, and the larval motility was impaired.
Animals↗
Parasites of domestic and wild animals in South Africa. XI. Helminths in cattle on natural pastures in the Northern Transvaal.
After being exposed to infestation for 4 to 6 weeks, pairs of tracer calves were slaughtered to determine the seasonal incidence of helminth infestation in cattle on natural pasture. Haemonchus placei was recovered from March-July and from November-February, and peak burdens were recorded during December and January. There was marked inhibition in larval development from April-July. Trichostrongylus spp. were recovered from March-June and from November-February, the greatest number of worms being recorded during December. Cooperia spp. infestation occurred from March-August and November-February with peak burdens during April-June and December. From February-August more than 50% of the worms recovered were in the 4th larval stage of development. The greatest number of Oesophagostomum radiatum were recovered from June-January. Longistrongylus sabie and Impalaia tuberculata, parasites normally found in impala, were recovered from many of the survey animals, this being the first record of their occurrence in cattle.
Animals↗
The nature and development of sex attractant specificity in cockroaches of the genus Periplaneta. IV. electrophysiological study of attractant specificity and its determination by juvenile hormone.
The antennae of male Periplaneta americana acquire a large number of olfactory receptors at the adult stage. Electrophysiological methods (single unit and electroantennogram recording) show that a portion of the receptors added at the adult ecdysis are sex attractant receptors. Sex attractant receptors are not present in large numbers on larval and adult female antennae. The differentiation of pheromone receptors is inhibited during normal larval development by juvenile hormone. Topical application of juvenile hormone-mimic to male antennae during the terminal larval instar inhibits their development. Comparative electrophysiological studies indicate a high degree of cross-reactivity of the P. americana sex attractant among four other species within the genus Periplaneta.
Action Potentials↗
Fatty acid synthetase complex from the insect Ceratitis capitata.
Fatty acid synthesis capacity of the insect Ceratitis capitata has been investigated in vitro from [1-14C]acetyl-CoA using homogenates at different stages of development. A maximum activity was observed after 5--6 days of larval development. But homogenates of the pharate adult insect did not show synthetic capacity of fatty acids. Fatty acid synthetase complex has been isolated from the particle-free supernatant fraction of homogenates from the 6-day C. capitata larvae. The enzyme complex was purified 182-fold with respect to the protein contained in the crude extract. The complex was homogeneous when analysed by gel filtration and by polyacrylamide-gel electrophoresis. The molecular weight was 5.2X10(5). The enzyme was dissociated into half-molecular subunits. Amino acid analysis, general properties, stability and kinetic constants (V and Km) for the substrates are reported. The fatty acid synthetase complex from the insect contains 42+/-1-SH residues and one phosphopatetheine moiety per 5.2X10(5). Activity was dependent on the presence of NADPH; FMN strongly inhibited the enzyme activity promoted by NADPH. The enzyme complex synthesized a range of fatty acid (10:0--18:0), palmitate being the predominant end product. The proportions of fatty acids synthesized varied with substrate concentrations. Fatty acids released from the complex were almost completely in the free form.
Amino Acids↗
[The relationship between the population count of black fly larvae and pupae (Simuliidae) in bodies of water and the number of attacking females].
Species of black flies, which develop in abundance in water bodies of Lower Priamurje and are potentially capable of bloodsucking, have not been registered near the blood donors. Only a few number of species developing in water attack for bloodsucking that apparently depends on unfavourable conditions of the larval development. A part of emerging females do not possess sufficient nourishing resources for completion of their gonotrophic cycle and need an additional bloodsucking. Of 35 registered species (27 of them possess morphological devices for bloodsucking) only 11 species attack. 4 species (Byssodon maculata ussuriana, Gnus malyshevi albipes, G. pavlovskii, Prosimulium ex gr. hirtipes) are mass bloodsuckers.
Animals↗
Incorporation of radioactive precursors into filarial larvae of Brugia developing in susceptible and refractory mosquitoes.
The incorporation of tritiated precursors injected into mosquito hosts parasitized by developing filarial larvae of Brugia patei has been studied by autoradiography in 2 species of mosquito, Aedes togoi in which filarial development was normal and Anopheles labranchiae atroparvus in which filarial development was abnormal. In both mosquito hosts there was significant incorporation into 4--5-day-old developing larvae of uridine and amino acids (isoleucine, leucine, valine, arginine, lysine, cystine, methionine, phenylalanine, tyrosine, tryptophan, histidine, and proline), although lower incorporation of methionine, tyrosine, and tryptophan was found during abnormal development. No incorporation of thymidine, hydroxytryptophan, dopa, or carbohydrate was found at this stage of larval development. Some incorporation of glucose and dopa was found in or around earlier stages of development in An. l. atroparvus. Mosquito flight muscle showed lower incorporation of glucose, but not of amino acids, around the site of filarial parasite development. The flight muscle of An. l. atroparvus showed a higher level of incorporation of lysine compared to that in A. togoi and higher levels of lysine and valine were found in the abnormally developing filarial larvae in the refractory mosquito.
Aedes↗
Development of Onchocerca volvulus in Simulium ochraceum and Simulium metallicum.
The development of Onchocerca volvulus was compared in Simulium ochraceum and S. metallicum by maintaining infected flies under uniform conditions. Larval development in S. ochraceum was synchronous and orderly so that nearly all larvae reaching the thoracic muscles from a single blood meal matured to third-stage infective larvae within 192 hours. In contrast, development in S. metallicum was asynchronous, slower, and retarded. In this species many first-larvae were malformed and stunted after the 5th day of development; and microfilariae and first- and second-stage larvae were still present 8--10 days after a single infecting blood meal when third-stage larvae had developed. The development of O. volvulus in S. ochraceum is more compatible with the intense transmission associated with human disease.
Animals↗
Phenogenetics of the eyeless-dominant mutant of Drosophila melanogaster.
The eyeless-Dominant (eyD) mutation is a fourth chromosome insertional translocation which affects the eyes, antennae, ocelli, and sexcombs when heterozygous but is a larval-pupal lethal when homozygous. By use of a crowding technique, it was possible to separate eyD homozygotes and heterozygotes with 100% accuracy at an early stage of larval development. Under these conditions, the eyD homozygotes had a biphasic lethal period since 45% died as first or second instar larvae and 55% died as pupae. The eyDleyD pupal lethal, isolated by this technique, was able to form all the adult structures with the exception of the eye-antennal disc derivatives. The brain was present but abnormal. In testing the competence of the eyDleyD larval eye discs by means of transplantation experiments, it has been demonstrated that the mutant discs develop non-autonomously. Histological studies have revealed the existence of neurological defects in both eyD heterozygotes and homozygotes. The eyDleyD lethal larvae lacked detectable optic formation centers and showed an extreme reduction in the number of cells present in the cortex of the brain. The ey"dleyD lethal pupae possessed partial formation centers and also had severe reduction in the number of cortical cells. The eyD heterozygotes possessed normal appearing formation centers but they did exhibit a moderate reduction in the number of their cortical cells as compared to wild-type. These studies have shown that there is a direct correlation between the extent of neurological damage and the time of developmental arrest. It appears that the eyD mutation must adversely affect the neuroblasts at a very early stage of development. As a working hypothesis, it is suggested that the eyD mutation operates via the same basic mechanism of cell death in heterozygous and homozygous animals.
Animals↗
[Morphology and development of the cysticercoids of Paricterotaenia porosa (Cestoda: Dilepididae)].
Studies of the development of Paricterotaenia porosa in its intermediate host Chironomus sp. were carried out. At 20 degrees C the development of the larva is completed in 24 days. The primary cavity is formed in 9 days, the separation of the cercomere anlage--in 11 to 12 days and the invagination of the larva--in 19 days. The larval development of P. porosa is characterized by its passing in the cavity of the external cyst, by the complete separation of anlages of the body of the larva and cercomere at the metamere stage and by the intensive growth of the cercomere after the invagination of the larva. The analysis of the cercomere structure suggests its protective function.
Animals↗
[Age specificity of the effect of 5-bromdeoxyuridine on the differentiation and puff spectrum of the salivary gland chromosomes of Drosophila virilis Sturt. I. Relationship between the viability of individuals and induction of new puffs and the period of action of 5-bromdeoxyuridine].
5-Bromodeoxyuridine (BUdR) influences the differentiation of the imaginal discs, larval viability and the chromosome puffing throughout the larval development. The differentiation of imaginal discs is more sensitive during the early 3rd instar. "cryptocephal" phenocopy appeared if the larvae were reared in the BUdR medium till the late 2nd instar. 2nd and 3rd instars are critical for the larval viability. During the period of the middle 3rd instar BUdR induced the complete spectrum of the newly forming specific puffs.
Age Factors↗