Variations in the amounts of glycogen,free sugars,lipids and phospholipids during embryonic development of Hyalomma dromedarii (Acarina:Ixodidae)

Changes in the amounts of glycogen, neutral free sugars, lipids and phospholipids during embryogenesis of Hyalomma dromedarii were examined. Chromatographic analysis of neutral free sugars revealed the presence of glucose, mannose, fructose, ribose, deoxyribose and inositol, but not of trehalose. Glucose is the principal free sugar during embryogenesis. Generally, the observed changes in the developmental profiles of the individual neutral free sugars suggest that they provide the material for glycogen biosynthesis and are themselves interconverted.Glycogen levels were very low in the newly oviposited eggs and remained so until day 12, after which they increased rapidly, remaining at high levels until hatching. In contrast, levels of lipids and phospholipids were high in the newly oviposited eggs. Total lipids exhibited a significant decrease during the first six days of embryogenesis whereas total phospholipids remained constant during this period of development. Thereafter total phospholipids underwent a significant decline on day 9 and reached their lowest levels on day 21, 24 and in the hatched larvae.     

Trypanosoma cruzi: pattern of RNA synthesis following infection of vertebrate cells

The pattern of RNA synthesis of intracellular Trypanosoma cruzi amastigotes, immediately following infection of Lesch-Nyhan human fibroblasts, was studied by autoradiography. Amastigote RNA synthesis, determined by [3H]guanine incorporation, was not detected until 2 h after infection. At 8 h postinfection more than 90% of intracellular amastigotes were labeled. It was verified that extracellular trypomastigotes also synthesized RNA. Therefore it was concluded that, if RNA is required for trypomastigote-to-amastigote transformation, this nucleic acid is already present in the trypomastigotes before infection of the vertebrate cell. It is probable that the RNA synthesized by amastigotes during the prereplicative lag period (the period between initial infection and the onset of DNA synthesis) is required for intracellular growth and reproduction.     

Trypanosoma Cruzi: Pattern of Rna Synthesis Following Infection of Vertebrate Cells

SYNOPSIS. the pattern of RNA synthesis of intracellular Trypanosoma cruzi amastigotes, immediately following infection of Lesch-Nyhan human fibroblasts, was studied by autoradiography. Amastigote RNA synthesis, determined by [₃H]guanine incorporation, was not detected until 2 h after infection. At 8 h postinfection more than 90% of intracellular amastigotes were labeled. It was verified that extracellular trypomastigotes also synthesized RNA. Therefore it was concluded that, if RNA is required for trypomastigote-to-amastigote transformation, this nucleic acid is already present in the trypomastigotes before infection of the vertebrate cell. It is probable that the RNA synthesized by amastigotes during the prereplicative lag period (the period between initial infection and the onset of DNA synthesis) is required for intracellular growth and reproduction.     

Effect of body size and sugar meals on oviposition of the yellow fever mosquito,Aedes aegypti (Diptera: Culicidae)

The effects of dietary sugar and body size on the oviposition of Ae. aegypti were studied under laboratory conditions. In female mosquitoes provided with sugar, the start of maximum fecundity was significantly delayed and the oviposition period was longer than in females provided with water. The peak of oviposition was also delayed in sugar‐fed females. Large females oviposited more eggs per day than small females at maximum fecundity and during eight days of observations. Large females also visited significantly more water‐containing cups in their cages per day than small females at maximum fecundity. During the eight days of observations, large females and sugar‐fed females visited more water‐containing cups in their cages than water‐fed small females. Both large females and sugar‐fed females oviposited their eggs at sites higher above the water line than water‐fed small females. These results suggested that large and sugar‐fed female Ae. aegypti mosquitoes had more energy reserves and oviposited their eggs at higher sites, which would lead to a time lag in hatching.     

Diurnal rhythm of nuclear RNA polymerase I activity in a duckweed, Lemna gibba G3, under continuous light conditions

The diurnal change of nuclear RNA polymerases I and II was examinedin a longday duckweed, Lemna gibba G3, under continuous lightconditions. RNA synthesis in crude nuclei was dramatically stimulatedby addition of the exogenous RNA polymerase of Escherichia coli,but not by the addition of calf thymus DNA. Treatment of crudenuclei with the supernatant fractions after precipitation ofthe nuclei decreased the RNA synthetic activity of the nucleiirrespective of the preparation time of both fractions. RNApolymerase I activity in crude nuclei, which was determinedin the presence of -amanitin at a low concentration of KCl,exhibited a diurnal rhythm but RNA polymerase II activity, whichwas presumed to be a portion of RNA synthesis inhibited by -amanitinin the presence of a high concentration of KCl, remained constantthroughout the day. Identical results were obtained when bothenzymes were solubilized widi ammonium sulfate and chromatographedon DEAE-Sephadex column. Both activities in the supernatantfraction obtained after precipitation of the nuclei did notchange diurnally. It was concluded, therefore, that the diurnalrhythm of RNA synthetic activity in the crude nuclei is dueto the RNA polymerase I activity and not the RNA polymeraseII activity. (Received August 29, 1978; )     

Induction of mictic females in the rotifer Brachionus: oocytes of amictic females respond individually to population-density signal only during oogenesis shortly before oviposition

1. One at a time during the reproductive period of amictic females, oocytes fill with yolk and undergo a mitotic maturation division (oogenesis), are oviposited as single cells, and then develop parthenogenetically into females. Sexual reproduction in Brachionus and several other genera is initiated when amictic females are crowded and oviposit some eggs induced to differentiate into mictic females. Mictic females produce haploid eggs that can develop parthenogentically into males or be fertilised and develop into diapausing embryos called resting eggs. 2. This study examines the time when oocytes in amictic females respond to maternal population density. Is the fate of all oocytes in the germarium irreversibly determined during the early postnatal life of the mother, or is each oocyte labile until just before oviposition? In the former case, the probability of an amictic female producing a mictic daughter at any time throughout her reproductive period would reflect the population density she experienced while young and not that at the time she oviposited an egg. 3. Amictic females of two clones of a Florida strain of B. calyciflorus were cultured singly from birth at a low or high density (in a large or small volume) until about halfway through their reproductive period and then switched (experimental treatment), or not (control treatment), to the other density condition. The results indicate that the female fate of an oocyte is determined by maternal population density during oogenesis. Eggs oviposited soon after transfer from low to high density had the same, or a higher, probability of becoming mictic females compared with those produced by control females kept at the high density; eggs oviposited after transfer from the high to the low density had the same low probability of becoming mictic females as those produced by control females kept at the low density. 4. Control females kept at the high density were less likely to produce mictic daughters as they aged. This decline is not because of a decreased propensity of older females to respond to crowding, as older females responded maximally when transferred from a low to a high population density. 5. As oocytes in amictic females respond to maternal population density only during oogenesis, there is a negligible lag between the population‐density signal in the environment and the commitment to sexual reproduction. This minimises the obligatory two‐generation lag between this signal and production of resting eggs, and thus reduces the possibility that crowding will lead to food limitation before production of these eggs.     

RNA content and RNA synthesis in diapause and non-diapause eggs of Bombyx mori

Changes in amount of RNA and its synthesis were studied in diapause and non-diapause eggs of Bombyx mori. In non-diapause eggs, the amount of total RNA began to increase at the stage of late gastrula and increased constantly thereafter. The synthesis of total and ribosomal RNA commenced at the onset of gastrulation, and after two days it levelled off. In contrast, the amount of total RNA in diapause eggs did not change essentially, and only a low level of total and ribosomal RNA synthesis was detected. On the other hand, if diapause eggs were activated by hot HCl treatment 24 hr after oviposition, the results obtained were essentially similar to those for non-diapause eggs, except that there was a lag of two days after acid treatment. These findings indicate that a significant control of ribosomal and other RNA occurs in relation to diapause and development.     

Incorporation of Radioactive Precursors into DNA and RNA of Plasmodium knowlesi in vitro

SYNOPSIS. Cultures of the intra-erythrocytic stages of Plasmodium knowlesi incubated in vitro utilized all the pre-formed radioactive purines tested (adenine, adenosine, deoxvadenosine, guanine, guanosine and hypoxanthine) but none of the pyrimidines (thymine, thymidine, uracil, uridine, cytidine and deoxycytidine). They did, however, utilize the pyrimidine precursor orotic acid.
All precursors analysed, including deoxyadenosine, were incorporated into both DNA and RNA (in the ratio of ∼1:3) but 19% was incorporated into other unidentified compounds. ³Hadenosine was incorporated into adenine and guanine residues of both DNA and RNA.
No unambiguous evidence was obtained for any periodicity in the synthesis of DNA or RNA in our cultures, even tho cultures remained as synchronous in vitro as they are in vivo. An estimate is presented of the amount of DNA made during one cycle in vitro.     

Physiological regulation of long-term oviposition in the house cricket, Acheta domesticus

In house crickets [Acheta domesticus (L.)] a single mating early in adult life sufficed to induce egg laying for the duration of the life of a female. Female house crickets mated readily shortly after adult emergence but oviposition did not commence until about 12–14 days after emergence, even though females matured eggs by 7 days. The egg-laying factor associated with mating remained active during prolonged periods of substrate deprivation during which the female did not oviposit. If the spermatophore was removed prematurely shortly after a mating, the long-term, egg-laying response was truncated and was correlated with a dramatic decline in the fertility of eggs which were oviposited. The egg-laying stimulus appeared to act in the spermatheca, apparently through neural means, since denervation of the spermatheca abolished mating-induced oviposition. These results indicate that the oviposition factor found in the testes is able to act for long periods of time and has to be present continually in order to be effective. Furthermore, the long-term oviposition stimulus in the house cricket may be different from prostaglandin E2 which induces a prompt ovipositional response.     

Evidence of cross-fertilization in a gonochoric population of the tadpole shrimp Triops numidicus (Crustacea: Branchiopoda: Notostraca)

Cross-fertilization was evident in a gonochoric population of the notostracan Triops numidicus, in which a thick, hard eggshell had been suspected of preventing the sperm from reaching the egg. Most of the eggs from copulated females hatched into larvae, but the eggs from virgin females did not develop. In the larvae, paternal DNA fragments were detected by AFLP. In histological sections, several spermatozoa were found in the shell of newly oviposited eggs in the brood pouches of copulated females, suggesting that the shell was still soft enough to be penetrated by spermatozoa. These results showed that copulation and subsequent fertilization achieved by penetration of sperm through the newly deposited eggshell were indispensable for the normal development of the eggs.     

Viral RNA Synthesis and Levels of DNA-Dependent RNA Polymerases During Replication of Adenovirus 2

The rates of RNA synthesis in cultured human KB cells infected by adenovirus 2 were estimated by measuring the endogenous RNA polymerase activities in isolated nuclei. The fungal toxin α-amanitin was used to determine the relative and absolute levels of RNA synthesis by RNA polymerases I, II, and III in nuclei isolated during the course of infection. Whereas the level of endogenous RNA polymerase I activity in nuclei from infected cells remained constant relative to the level in nuclei from mock-infected cells, the endogenous RNA polymerase II and III activities each increased about 10-fold. These increases in endogenous RNA polymerase activities were accompanied by concomitant increases in the rates of synthesis in isolated nuclei of viral mRNA precursor, which was monitored by hybridization to viral DNA, and of viral 5.5S RNA, which was quantitated by electrophoretic analysis on polyacrylamide gels. The cellular RNA polymerase levels were measured with exogenous templates after solubilization and chromatographic resolution of the enzymes on DEAE-Sephadex, using procedures in which no losses of activity were apparent. In contrast to the endogenous RNA polymerase activities in isolated nuclei, the cellular levels of the solubilized class I, II, and III RNA polymerases remained constant throughout the course of the infection. Furthermore, no differences were detected in the chromatographic properties of the RNA polymerases obtained from infected or control mock-infected cells. These observations suggest that the increases in endogenous RNA polymerase activities in isolated nuclei are not due to variations in the cellular concentrations of the enzymes. Instead, it is likely that the increased endogenous enzyme activities result from either the large amounts of viral DNA template available as a consequence of viral replication or from functional modifications of the RNA polymerases or from a combination of these effects.     

Purine nucleotide content of developing Ascaris lumbricoides eggs

Farland W. H. &; Macinnis A. J. 1978. Purine nucleotide content cf developing Ascaris lumbricoides eggs. International Journal for Parasitology8: 177–186. Populations of Ascaris lumbricoides eggs obtained from the terminal portion of the uteri of mature females were shown to develop synchronously, allowing the detection of quantitative and qualitative changes in nucleotide content during development. Application of a method for the preparation of perchloric acid-soluble fractions from Ascaris eggs utilizing Alamine 336S in chloroform is described. This method was useful in neutralizing the extract and for removal of interfering lipids.Guanine nucleotides were found in high concentration in ovarian tissue of adult female worms, and comprise more than 80% of the total acid-soluble nucleotides in 0-day eggs. Muscle tissue contained a predominance of adenine nucleotides.To determine the fate of large concentrations of guanine nucleotides present in 0-day eggs, perchloric acid-soluble fractions were prepared from embryonating eggs on various days of development. Nucleotide content was determined after fractionation on DEAE-cellulose columns,A dramatic decrease (6·2 fold) in guanine nucleotides between 5 and 8 days' embryonation was seen; [GMP] and [GDP] showed the greatest change. ATP concentration increases 3·3 fold through 21 days' embryonation. The total acid-soluble nucleotide content decreased 60% during this time. Uric acid, an end product of purine metabolism, was detectable in 5-day eggs and accumulated through the course of embryonation. The decrease of guanine nucleotides correlates temporally with the increase in DNA content during embryonation. The methodology and results of this study provide a basis for additional study of nucleic acid metabolism during development of Ascaris eggs.     

Plant Desiccation and Protein Synthesis: III. Stability of Cytoplasmic RNA during Dehydration, and Its Synthesis on Rehydration of the Moss Tortula ruralis

RNA species from the haploid gametophyte generation of the moss Tortula ruralis exhibit typical eukaryotic characteristics. The major ribosomal and soluble RNA species are stable during drying and rehydration. RNA synthesis occurs rapidly on reintroduction of the moss to water and incorporation into high molecular weight RNA fractions was detected after 20 to 30 minutes of rehydration and into low molecular weight fractions after 30-60 minutes. Newly synthesized ribosomal RNA was detected in ribosomes within 2 hours of rehydration, but not in polysomes. It is apparent that the ribosomal and transfer RNA conserved during desiccation is involved in the re-establishment of early protein synthesis during subsequent rehydration and that, initially, there is no requirement for newly synthesized material.     

RNA associated with nonhistone chromosomal proteins of dog liver

The nonhistone chromosomal proteins were separated on Sephadex G-200 into 3 fractions of which two were associated with 3S RNA. The RNA eluted with fraction I (guanine + cytosine content 54%) is tightly bound to the proteins from which it can be separated only after digestion with pronase. The RNA associated with fraction III (guanine + cytosine content 64%) can be separated from the proteins directly by chromatography on DEAE-Sephadex A 25. No dihydropyrimidines have been detected in any of the two RNAs.     

Diapause in the mite Metaseiulus occidentalis: Stages sensitive to photoperiodic induction

Stages of Metaseiulus occidentalis sensitive to photoperiod induction of diapause were determined by transferring various stadia into diapause-inducing conditions, and rearing them until adult females could be scored for reproductive condition. When eggs were transferred to 10 hr light at 19°C from 24 hr light at 25°C and the mites reared to adults, 92 per cent entered diapause. When larvae and all subsequent stages were kept under the inductive conditions, 62 per cent of adult females diapaused. Mites transferred as protonymphs into inductive conditions yielded only 10 per cent in diapause, and mites transferred as deutonymphs or newly emerged females did not enter diapause.However, adult females reared from eggs at 19°C under 12 hr light (which is near the critical photophase of 11·2 hr at 19°C) showed an unexpected sensitivity to photoperiod. Some newly emerged females oviposited upon transfer to an 8 hr photophase at 19°C. Some then stopped ovipositing and apparently entered diapause; these females resumed ovipositing after intervals ranging from 34 to 100 days. This was termed ‘switching’ into diapause. Some females reared under a 16 hr photophase at 19°C ‘switched’ also upon transfer as adults to shorter photophases—either 8 or 12 hr at 19°C. Thus, ‘switching’ may be due to transfer to shorter photophases. Promptness of mating vs delayed mating allowed ‘switching’ to be more easily detected.     

In vitro synthesis of simian virus 40 DNA. I. Synthesis by a soluble extract from infected CV1 cells.

Simian Virus 40 (SV40) DNA replication was studied in vitro using cell free extracts prepared from SV40 infected CV1 cells. The cells were fractionated into a soluble cytoplasmic fraction and nuclei. The nuclei were lysed with high salt and used to prepare a soluble nuclear fraction. Both fractions displayed DNA polymerase activity as measured with activated calf thymus DNA. However, only the cytoplasmic fraction was active when SV40 DNA comonent I molecules were used as template. Under these conditions, the cytoplasmic extract was shown to catalyse the SV40 DNA dependent, in vitro incorporation of the four deoxyribonucleotides into DNA molecules which had, at both neutral and alkaline pH, the same sedimentation behavior as authentic SV40 DNA component I and component II molecules. Optimal Mg++ concentration was 5-8 mM. Incorporation of label into DNA component I molecules showed an initial lag of about 15 min., after which it was linear with time for up to 5 hrs at 32 degrees. Incorporation into DNA component II molecules proceeded without obvious lag and reached a plateau after approximately 2 hrs of incubation. It is concluded that the cytoplasmic extract supports the in vitro synthesis of SV40 DNA and that DNA component II molecules appear to be a precursor to DNA component I molecules in the reaction. Labeling of viral DNA molecules was highly dependent on ATP and on an ATP generating system. In the absence of ATP and of the energy generating system, incorporation occurred but both template and newly synthesized DNA molecules were extensively degraded.     

Clustered male production by workers in the stingless bee Melipona subnitida Ducke (Apidae, Meliponinae)

Summary: In stingless bees brood cells are sequentially filled with liquid larval food (mass-provisioning), upon which the queen lays an egg. Thereafter the cell is closed by a worker. This study showed that during these processes workers of Melipona subnitida regularly laid eggs that served as food for the queen. Occasionally cells were oviposited in and immediately closed by a worker. These cells always rendered males. Some of these reproductive workers were seen to lay a trophic egg as well. Cells which were exclusively oviposited in by the physogastric queen gave rise to workers and queens only. In one colony it could be verified that three workers alone, which differed in age by one day, laid 15 male-producing eggs within a period of two successive weeks. Among them the number of ovipositions was positively related to the order in which workers eclosed - the oldest worker laying most eggs - and inversely related to the number of times they closed cells oviposited in exclusively by the queen. Apparently the physogastric queen was not able to stop certain workers from reproducing. We therefore conclude that some workers in M. subnitida temporarily dominated their queens in egg-laying.     

Life Cycle of the Mulberry Longicorn Beetle,Apriona germari Hope on an Artificial Diet

Mulberry longicorn beetle, Apriona germari, was reared on an artificial diet to investigate its life cycle. Average egg period was 17.95 days. Most larvae pupated at the 8th (33.3%) or 9th (33.3%) instars, but others emerged from the 7th to the 11th instars. The total duration of larval stage from the 1st to the end of the 9th and the 11th instars were 176.2 and 251.5 days, respectively. For terminatiopn of diapause and acceleration of pupation, low temperature treatment at 5°C for 60 days was highly effective. Average pupal period for female and male was 19.3 and 18.4 days, respectively. Average longevity of adults was similar with 40.5 days for female and 44.3 days for male. Mating had occurred from about 10 days after the adult emergence, and then a female adult laid one or two eggs per day. Average number of eggs oviposited by a female was approximately 47.7. Total life span of A. germari, when reared on an artificial diet in the laboratory, ranged broadly from 197.5 days to 331.5 days mainly depending on the larval period.     

THE BASE COMPOSITION OF NUCLEIC ACIDS IN CHROMOSOMES, PUFFS, NUCLEOLI, AND CYTOPLASM OF CHIRONOMUS SALIVARY GLAND CELLS

The base composition of RNA from individually isolated giant chromosomes, puffed chromosome segments, nucleoli, and samples of cytoplasm from Chironomus salivary gland cells was determined by microelectrophoresis. Data on the adenine: guanine quotient of the chromosomal DNA were also obtained. The results show that: 1) Chromosomal, nucleolar, and cytoplasmic RNA's differ significantly from each other in base composition. 2) Nucleolar and cytoplasmic RNA's, in spite of the difference, show great similarities with regard to the base composition and are both rich in adenine and uracil. 3) The RNA extracted from chromosome I differs significantly from the RNA's extracted from different segments of chromosome IV, and the latter differ significantly from each other. 4) The values for the RNA: DNA quotients of chromosome segments parallel the development of synthetically active genes, so-called Balbiani rings. 5) The chromosomal RNA does not show a base symmetry in any of the investigated cases, nor is the content of guanine + cytosine the same as that for DNA. The first of these two facts excludes the possibility that the chromosomal RNA is a complete copy of both strands of the chromosomal DNA. In spite of the difference in guanine + cytosine content between the two nucleic acids the RNA may still partly or completely be a single strand copy depending upon how representative the DNA values are for the synthetically active DNA.