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  • Drosophila  (158)
  • Calcium
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  • 1
    ISSN: 1436-6215
    Keywords: Strontium ; oraler Strontium-Test ; Calcium ; Absorption ; gesunde Probanden ; Strontium ; oral strontium test ; calcium ; absorption ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary Intestinal strontium absorption has been discussed recently as an indirect measure for calcium uptake. Prerequisite for the clinical use of an oral strontium test is the availability of a reliable procedure including controlled strontium supply, sample pretreatment and analysis as well as the assessment of normal values. In the present study, a group of young females (n=33; 24.0 ± 2.7 y; BMI 21.5 ± 1.9) received an oral dose of 2.27 mmol strontium in a standardized breakfast that contained 0.625 mmol calcium. Before and 220 min after the bolus serum strontium concentrations were determined by means of atomic absorption spectrophotometry (coefficient of variation: within day 4.8 %, n=10; day-to-day 9.5 %, n=8). The error of the method was 2.7 %. Calculation of the fractional strontium absorption rate considered the respective distribution volume (extracellular fluid; either estimated using body weight or determined by means of bioimpedance analysis [BIA]). Average absorption rates were 13.3 ± 3.1 % and, considering BIA measurement 13.6 ± 2.6 %, respectively. Smoking, exercise and, use of oral contraceptives showed no effects. Our oral strontium test is characterized by excellent reliability, easy handling and low costs and, thus, is suitable for routine use.
    Notes: Zusammenfassung Die Erfassung der Strontiumabsorption wird heute als indirektes Verfahren zur Beurteilung der intestinalen Calciumabsorption diskutiert. Voraussetzung für die klinische Anwendung ist ein vertrauenswürdiges Testverfahren inclusive kontrollierter Strontiumgabe, Probenaufarbeitung und -analyse sowie die Erfassung von Normalwerten. Für unsere Studien wurde ein Kollektiv junger Frauen (n=33, 24,0 ± 2,7 Jahre; BMI 21,5 ± 1,9) herangezogen. Die Probandinnen erhielten eine Bolusgabe von 2,27 mmol Strontium zusammen mit einem Standardfrühstück (ca. 0,625 mmol Calcium). Vor und 220 min nach der Bolusgabe erfolgte die Bestimmung des Serum-Strontiumgehaltes mittels Atomabsorptionsspektrometrie. Der Variationskoeffizient der Methode lag innerhalb eines Tages bei 4,8 % (n=10) und von Tag zu Tag 9,5 % (n=8). Der Fehler der Methode betrug 2,7 %. Die Berechnung der fraktionellen Strontiumabsorptionsrate erfolgte unter Berücksichtigung des entsprechenden Verteilungsraumes (Extrazellulärflüssigkeit; Schätzverfahren über Körpergewicht bzw. Bioimpedanz-Analyse [BIA]). Die Strontiumabsorptionsrate lag im Mittel bei 13,3 ± 3,1 %, unter Berücksichtigung der BIA-Werte bei 13,6 ± 2,6 %. Rauchen, sportliche Aktivität bzw. Einnahme oraler Kontrazeptiva zeigten keinen Einfluß. Das hier vorgestellte Testverfahren ist aufgrund seiner hohen Vertrauenswürdigkeit und relativ einfacher Handhabung für Routine-untersuchungen geeignet.
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  • 2
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    Entomologia experimentalis et applicata 76 (1995), S. 25-35 
    ISSN: 1570-7458
    Keywords: dispersal ; flight duration ; cactophilic ; Drosophila ; age effects ; body size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The flight ability ofDrosophila aldrichi (Patterson & Crow) andD. buzzatii (Patterson & Wheeler) using tethered flights, was measured with respect to age-related changes, genetic variation and adult body size variation induced by rearing at different larval densities.Drosophila buzzatii flew for much longer thanD. aldrichi, especially females, but age-related changes in flight duration were significant only forD. aldrichi. Effects of body size on flight ability were significant inD. buzzatii, but not inD. aldrichi. InD. buzzatii, there was a significant genotype-environment interaction (larval density × line) for flight duration, with short and average flight duration isofemale lines showing longer flights, but a long flight duration line shorter flights as body size decreased (i.e., as larval density increased). Heritability estimates for flight duration were similar in the two species, but flight duration showed no significant genetic correlations with developmental time, body size or wing dimensions (except for one wing dimension inD. buzzatii). Although not significantly different between the species, heritabilities for life-history traits (adult size and developmental time) showed contrasting patterns — with higher heritability for body size (body weight and thorax length) inD. buzzatii, and higher for developmental time inD. aldrichi. In agreement with limited previous field evidence,D. buzzatii is better adapted for colonization than isD. aldrichi.
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  • 3
    ISSN: 1572-8773
    Keywords: metallothionein ; development ; metal induction ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Expression of the two Drosophila melanogaster metallothionein genes, Mtn and Mto, has been analyzed by in situ hybridization during post-embryonic development. Mtn and Mto transcripts were detected exclusively in the digestive tract of larvae, pupae and adults reared on standard medium. Mtn and Mto expression domains overlap, but each gene is also expressed at unique sites. Mtn mRNA levels are approximately 10 and 20 times higher than those of Mto in larvae and adults, respectively. Copper and cadmium ions strongly induce Mtn and Mto mRNA accumulation in the midgut. Zinc is a weaker inducer, acting only at high concentrations. Mtn gene expression is induced by these three metals in Malpighian tubules, while Mto gene expression in this organ is induced only by zinc. Iron is a poor inducer of metallothionein mRNA accumulation. Functions of MTN and MTO proteins in metal homeostasis and detoxification are considered.
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  • 4
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    Journal of solution chemistry 21 (1992), S. 525-532 
    ISSN: 1572-8927
    Keywords: Calcium ; molybdate ; aqueous ; thermodynamic ; complexation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The solubility of powellite [CaMoO4(c)] was studied in aqueous Na2MoO4, CaCl2 and Ca(NO3)2 solutions ranging in concentrations from 1×10−4M to 1.0M and over equilibration times extending to 36 days. Our experimental data were interpreted using the aqueous ion-interaction model of Pitzer and coworkers. The Ca2+−MoO 4 2− ion-interactions were found to be analogous to Ca2+−SO 4 2− . The use of Ca2+−MoO 4 2− ion-interactions parameters (β(0)=0.2, β(1) = 3.1973 and β(2)) and a logK sp of −7.93 gave excellent predictions of all of the experimental data. Commonion ternary interaction parameters such as MoO 4 2− −Cl− or MoO 4 2− −NO 3 − were not required.
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  • 5
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    Cellular and molecular life sciences 47 (1991), S. 111-114 
    ISSN: 1420-9071
    Keywords: Drosophila ; repeat matings ; polyandrous pattern diversity ; sperm length
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to test the validity of the prediction of the mating pattern of females from the sperm length distribution in males, three species ofDrosophila were analysed. Males in the three species are equally polygynous but females differ in the level of polyandry. A ‘low recurrence polyandry’ is observed in the sperm dimorphic speciesD. affinis while a ‘high recurrence polyandry’ is observed in the sperm monomorphic speciesD. latifasciaeformis andD. littoralis. These results are consistent with the hypothesis proposed previously that sperm dimorphism in males can only be maintained by a selective alternative in females (i.e. facultative female polygamy), whereas a stricter mating system (e.g., ‘obligatory’ polyandry) should only result in sperm monomorphism irrespective of the absolute value of sperm length.
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  • 6
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    Cellular and molecular life sciences 51 (1995), S. 976-979 
    ISSN: 1420-9071
    Keywords: Calcium ; T lymphocytes ; aging ; psychosocial stress ; overcrowding ; animal housing ; lymphocyte activation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Intracellular calcium concentration is a sensitive marker of the homeostasis of living cells, and its increase is an essential step of T lymphocyte activation. Changes in the environment provoke an adaptive stress-response of the organism. In our present work we have investigated the effect of chronic overcrowding on resting and lectin-stimulated cytoplasmic free calcium concentration of splenic T lymphocytes from young and aged CBA/CA mice (50 animals total). The animals were kept under ‘normal’ (68 cm2/animal) or ‘overcrowded’ (22 cm2/animal) conditions for 3 months. Young animals showed no change in resting and stimulated calcium after overcrowding. T cells from aged mice, however, displayed significantly smaller levels of both resting and lectin-stimulated intracellular calcium concentration (p〈0.01 each), as compared to those of the non-stressed, aged animals. This inadequate adaptation in the calcium metabolism of T lymphocytes may significantly contribute to the diminished immune response of the aged in stress.
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  • 7
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    Journal of industrial microbiology and biotechnology 7 (1991), S. 41-44 
    ISSN: 1476-5535
    Keywords: Efrotomycin ; Calcium ; Nocardia lactamdurans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary Efrotomycin is a modified polyketide antibiotic of the elfamycin family that has use in the area of pig husbandry. Optimization of the fermentation medium for production of efrotomycin byNocardia lactamdurans revealed that the fermentation is sensitive to hard water and certain lots of cottonseed flour used to prepare a complex fermentation medium. A limited metal ion analysis of the hard water indicated that calcium ions are present at concentrations found to be inhibitory by the addition of calcium chloride to medium prepared with distilled water. Similarly, a correlation between lots of cottonseed flour that poorly supported the fermentation and high calcium levels is presented. Further experimentation revealed that by altering the sterilization conditions of the cottonseed flour, the inhibitory effect of poor lots could be prevented.
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  • 8
    ISSN: 1432-1890
    Keywords: Calcium ; Iron ; Lead ; Phosphorus ; Short roots ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Norway spruce [Picea abies (L.) Karst.] seedlings, nonmycorrhizal of mycorrhizal with Laccaria laccata or Paxillus involutus were grown in a quartz sand-nutrient solution system for 6 months and then treated with 5 μM Pb for 4 days. Element contents of cortex cell wall of young, medium and old short roots were determined by X-ray microanalysis of longitudinal thin sections. The Pb content was influenced neither by age nor by the distance from the root tip (up to 1.7 mm) but was significantly lower in the P. involutus mycorrhizae than in the L. laccata mycorrhizae or in nonmycorrhizal short roots. In the P. involutus mycorrhizae, the P content of the cortex cell walls was twice as high in young mycorrhizae than in old mycorrhizae. In the nonmycorrhizal short roots and the L. laccata mycorrhizae, P content was influenced neither by age nor by distance from the root tip. The Ca and Fe contents of the cortex cell walls increased with age in the nonmycorrhizal short roots and the mycorrhizae. It is concluded that the element content of the cortex cell walls of short roots is strongly influenced by age, while the distance from the root tip seems to be of minor importance.
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  • 9
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    Calcified tissue international 30 (1980), S. 209-216 
    ISSN: 1432-0827
    Keywords: Calvarium ; cAMP ; Vitamin D3 metabolites ; Calcium ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Results from in vitro works suggest that 1,25- and 24,25-dihydroxyvitamin D3 (1,25-(OH)2D3 and 24,25-(OH)2D3) act on bone via different mechanisms. The present investigation was performed to study the effect of these two metabolites and of their precursor 25-hyxdroxyvitamin D3 (25-(OH)D3) on bone cAMP content in vitro. Rats' paired half calvaria were incubated under sterile conditions with one vitamin D3 derivative (10−13 to 10−9 M) or with ethanol (0.005 ml for 15 min to 24 h in 1 ml medium containing 0, 0.2, 1, 2, or 3 mM calcium. In some experiments: (a) cycloheximide (10−5M) was added simultaneously with the vitamin D3 metabolites; (b) 1–84 bPTH (5 × 10−8 M) was added for 5 or 15 min at the end of the 24 h incubation. Calvaria were immersed in 1 ml TCA 5% 4°C and homogenized. The cAMP was extracted with diethylether and measured by a competitive protein binding assay. Results bring further evidence for a particular effect of low doses of 24,25-(OH)2D3 (10−9 to 10−12M) and of 25-(OH)D3 (10−9 to 10−11M) on bone, different from that of 1,25-(OH)2D3: cAMP content was higher in 24,25-(OH)2D3- or 25-(OH)D3-treated and lower in 1,25-(OH)2D3-treated calvaria than in ethanol-treated ones with 1 mM calcium. The 1,25-(OH)2D3 effect persisted in calcium-free medium whereas 25-(OH)D3 and 24,25-(OH)2D3 effects could not be observed with 0 mM nor with 3 mM calcium. The required duration of the preincubation (over 1 h) as well as the inhibitory action of cycloheximide may suggest an involvement of protein synthesis in the vitamin D3 metabolites effects. Neither 1,25-(OH)2D3 nor 24,25-(OH)2D3 affected the PTH-induced increase in bone cAMP content.
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  • 10
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    Calcified tissue international 32 (1980), S. 201-206 
    ISSN: 1432-0827
    Keywords: Magnesium ; Parathyroid hormone ; Secretion ; In vitro ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In a well-defined in vitro perifusion system, the effects of extracellular magnesium concentration (Mg) on parathyroid hormone (PTH) secretion by bovine parathyroid tissue were examined. At Mg less than 0.8 mM, the ability of the glands to secrete hormone maximally in response to low calcium (Ca) stimulation was progressively impaired. Low Mg also impaired the ability of isoproterenol, dibutyryl cyclic AMP and theophylline to stimulate hormone release. The defect in hormone release at low Mg observed in vitro was analogous to the well-documented inhibition of secretion observed in vivo. Increases in Mg from 0 to 0.8 mM rapidly repaired the defect in hormone secretion. At Mg above 1.0 mM there was a Ca-like effect on hormone release, with a progressive decrease in secretion at increased Mg. Although its mechanism is not yet clear, the low Mg effect appears to impair principally the process of hormone release rather than its biosynthesis or storage.
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  • 11
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    Calcified tissue international 50 (1992), S. 391-396 
    ISSN: 1432-0827
    Keywords: Bone ; Matrix ; Phosphoproteins ; Biomineralization ; Calcium ; Nucleation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Osteopontin, bone sialoprotein, and bone acidic glycoprotein-75 are three acidic phosphoproteins that are isolated from the mineralized phase of bone matrix, are synthesized by osteoblastic cells, and are generally restricted in their distribution to calcified tissues. Although each is a distinct gene product, these proteins share aspartic/glutamic acid contents of 30–36% and each contains multiple phosphoryl and sialyl groups. These properties, plus a strict relationship of acidic macromolecules with cell-controlled mineralization throughout nature, suggest functions in calcium binding and nucleation of calcium hydroxyapatite crystal formation. However, direct proof for such roles is still largely indirect in nature. The purpose of this review is to present two speculative hypotheses regarding acidic phosphoprotein function. The goal was to use new sequence information along with database comparisons to develop a structural rationalization of how these proteins may function in calcium handling by bone. For example, our analysis has identified a conserved polyacidic stretch in all three phosphoproteins which we propose mediates metal binding. Also, conserved motifs were identified that are analogous with those for casein kinase II phosphorylation sites and whose number correlates well with that of phosphoryl groups/protein. A two-state conformational model of calcium binding by bone matrix acidic phosphoproteins is described which incorporates these findings.
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  • 12
    ISSN: 1432-0827
    Keywords: Calcitonin ; Antibodies ; Calcium ; Osteoporosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In order to evaluate the potential inhibition of the acute anti-osteoclastic activity of salmon calcitonin (SCT) by specific antibodies (Ab), we compared the SCT-induced hypocalcemic effect in young male rabbits with significant titers of high affinity Ab and in matched animals without Ab. Immunization of rabbits was performed by repetitive s.c. injections of SCT and Freund adjuvant. Ab were present in four-fifths of SCT-treated rabbits (Ab+). Their titer varied from 0.8×10(-9) to 30×10(-9) M/liter and their constant of affinity from 0.97×10(9) to 4.2×10(9) L/M. Intravenous injection of 1 IU/kg SCT to Ab+ rabbits induced a significant decrease (P〈0.01) of ionized serum calcium (Ca2+) after 30 minutes (mean±SD:-9±0.6%) and until the 240th minute of the test (-16.7±4.7%), with a maximum after 120 minutes (-22.6±2%). This was not significantly different from the hypocalcemic effect measured after the same procedure performed in matched animals without Ab (Ab-): significant decrease in Ca2+ (P〈0.01) after 30 minutes (-8.2±2.2%), maximal after 150 minutes (-23.2±4.9%), and lasting until 210 minutes (-14.5±3.7%). We conclude that, in the particular model of the male young rabbit, specific anti-SCT Ab do not block or reduce the acute anti-osteoclastic activity of SCT.
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  • 13
    ISSN: 1432-0827
    Keywords: Computed tomography ; Trabecular bone density ; Strontium ; Calcium ; Atomic absorption spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Changes in the average linear attenuation coefficient (LAC) within a fixed measurement volume in the proximal end of the dog tibia, which contains trabecular bone and associated soft tissues (the trabecular bone “space”), were monitored continuously using gamma-ray computed tomography (γ-CT) prior to, during, and following intravenous infusion of strontium (Sr) lactate. An infusion of 1.3–4.7 g of Sr over a period of 110–160 minutes into 20-kg dogs resulted, within 6–8 hours, in an increase of 0.019–0.045 cm-1 (P〈0.002) in the LAC. Calibration of the γ-CT system showed that 0.44 mg/cm3 of Sr produced a change of 0.01 cm-1 in the LAC. Using this conversion factor, the Sr concentration in the trabecular bone space resulting from infusion, as measured by flame atomic absorption spectroscopy, agreed with that predicted by the change observed in the LAC. Sr present in the serum and urine was consistent with the changes observed in the LAC over the study period. Control dogs infused with mineral-free solutions showed no change in LAC. Calcium equivalents required to give the changes observed in the LAC using Sr indicate that variations in skeletal turnover in man can be monitored in the peripheral skeleton using γ-CT.
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  • 14
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    Calcified tissue international 51 (1992), S. 42-47 
    ISSN: 1432-0827
    Keywords: Kidney ; Endoplasmic reticulum ; Calcium ; In vivo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Calcium uptake by the endoplasmic reticulum (ER) is important for cellular calcium homeostasis, yet its regulation in nonmuscle cells is poorly understood. We reported that Ca2+ uptake by a light fraction of canine renal cortical ER (LER) is stimulated by protein kinase C in vitro. Here we describe conditions in vivo that stimulated renal cortical LER Ca2+ uptake. Thirty minutes after contralateral nephrectomy in the dog, 45Ca2+ uptake into renal cortical LER was increased 42% above control LER. There was no difference in LER Ca2+ uptake 24 hours after uninephrectomy. Acute denervation did not reproduce the increase in LER 45Ca2+ uptake seen at 30 minutes after uninephrectomy, nor did prior thyroparathyroidectomy abolish it. Forty-eight hours after thyroparathyroidectomy, 45Ca2+ uptake activity into renal cortical LER was decreased ≈sevenfold. In a proximal tubular cell line (LLC-PK1), 30-minute incubation with 12-O-tetradecanoylphorbol-13-acetate doubled 45Ca2+ uptake into a nonmitochondrial pool. Pretreatment with epidermal growth factor halved ER Ca2+ uptake, whereas insulin-like growth factor and growth hormone, alone or in combination, had no effect. Our data suggest that Ca2+ uptake into renal cortical ER is stimulated acutely during compensatory renal growth, perhaps through protein kinase C, and is stimulated chronically by parathyroid hormone.
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  • 15
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    Journal of molecular evolution 41 (1995), S. 1152-1159 
    ISSN: 1432-1432
    Keywords: Synonymous substitutions ; Nonsynonymous substitutions ; Estimation methods ; Confidence intervals ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for estimating the numbers of synonymous (Ks) and nonsynonymous (Ka) substitutions per site is proposed. The method is based on the Li's (J Mol. Evol. 36:96–99, 1993) and Pamilo and Bianchi's (Mol. Biol. Evol. 10:271–281, 1993) method, but a putative source of bias is solved. It is proposed that the number of synonymous substitutions that are actually transitions or transversions should be computed by separating the twofold degenerate sites into two types of sites, 2S-fold and 2V-fold, where only transitional and transversional substitutions are synonymous, respectively. Kimura's (J. Mol. Evol. 16:111–120, 1980) two-parameter correcting method for multiple substitutions at a site is then applied using the overall observed synonymous transversion frequency to estimate both the numbers of synonymous transversional (Bs) and transitional (As) substitutions per site. This approach, therefore, also minimizes stochastic errors. Computer simulations indicate that the method presented gives more accurate Ks and Ka estimates than the aforementioned methods. Furthermore, the obtention of confidence intervals for divergence estimates by computer simulation is proposed.
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  • 16
    ISSN: 1432-1432
    Keywords: Evolution ; Expression patterns ; α-Amylase ; Glucose repression ; Starch induction ; Intra- and interspecific variation ; Drosophila ; Gene expression ; Regulatory genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Intraspecific variation of α-amylase activity in D. melanogaster and D. immigrans, which is distantly related to D. melanogaster, and interspecific variation of α-amylase activity in 18 Drosophila species were examined. The amount of intraspecific variation of α-amylase activities measured in terms of coefficient of variation in D. melanogaster and D. immigrans was one-half and one-tenth or less, respectively, of the interspecific variation in 18 Drosophila species. We also surveyed the response patterns of α-amylase activity to dietary carbohydrates at the larval and adult stages. The levels of α-amylase activity depended on both repression by dietary glucose (glucose repression) and induction by dietary starch (starch induction). In general, our data suggest that glucose repression was conserved among species at both stages while starch induction was mainly observed in larvae, although the degree of the response depended on species. In D. lebanonensis lebanonensis and D. serrata, larvae expressed electrophoretically different α-amylase variants (isozymes) from those of adult flies. These results may suggest that the regulatory systems responsible both for the response to environment and developmental expression are different among species in Drosophila.
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  • 17
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    Journal of molecular evolution 33 (1991), S. 156-162 
    ISSN: 1432-1432
    Keywords: Drosophila ; Mitochondrial DNA ; Nucleotide sequence ; Nonsynonymous substitutions ; Phylogeny ; A+T content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of a segment of the mitochondrial DNA from threeDrosophila species (D. erecta, D. eugracilis, andD. takahashii), belonging to different subgroups of themelanogaster group has been determined. The segment encompasses three complete tRNA genes (tRNAtrp, tRNAcys, and tRNAtyr) and portions of two protein-coding genes: the subunit 2 of the NADH dehydrogenase (ND2) and the subunit 1 of the cytochrome oxidase (COI). Comparisons also involve homologous sequences already known for four otherDrosophila species of themelanogaster group. Length differences were confined in the intergenic region where a long stretch of AT repeats was observed in one of the species analyzed. The three tRNA genes exhibit very different evolutionary rates, the most slowly evolving one, tRNAtyr, is adjacent to the 5′ end of COI; tRNAs in similar positions have been previously shown to evolve slowly because they are probably involved in transcript processing. Although the rate of synonymous substitutions was very similar between ND2 and COI genes there were strong discrepancies between them in terms of the number of nonsynonymous substitutions. Differences have also been found in G+C content of the genes, which are likely to be linked to different selective pressures. There is a reduction in G+C content in the region where selective constraints are reduced. This suggests the existence of different levels of constraints along the sequenced segment. An overall analysis of the types of substitutions showed a decrease in A+T content during the course of evolution of the species.
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  • 18
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    Journal of molecular evolution 35 (1992), S. 51-59 
    ISSN: 1432-1432
    Keywords: Drosophila ; Gart locus ; Chironomus tentans ; Purine nucleotide biosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Drosophila Gart locus consists of two genes. One gene encodes three enzymes in the de novo purine nucleotide biosynthesis pathway [glycinamide ribonucleotide synthetase (GARS), aminoimidazole ribonucleotide synthetase (AIRS), and glycinamide ribonucleotide transformylase (GART)]. The second gene lies within an intron of the purine gene and encodes a cuticle protein. To investigate the evolution of the Gart locus, the Chironomus tentans homolog was cloned by screening a genomic DNA library with a polymerase chain reaction product. This study shows that the interesting structural features of this locus conserved in two distant Drosophila species are not found in the Chironomus homolog. These features include the cuticle protein gene nested within an intron and the existence of an alternative transcript to yield a monofunctional enzyme. In addition, the extremely rapid divergence of coding sequence seen for members of the tandemly duplicated AIRS domain in Drosophila is found to be much less rapid in Chironomus.
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  • 19
    ISSN: 1432-1432
    Keywords: Drosophila ; per gene ; Threonine-Glycine ; repeat sequence ; melanogaster subgroup phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The Threonine-Glycine (Thr-Gly) region of the period gene (per) in Drosophila was compared in the eight species of the D. melanogaster subgroup. This region can be divided into a diverged variable-length segment which is flanked by more conserved sequences. The number of amino acids encoded in the variable-length region ranges from 40 in D. teissieri to 69 in D. mauritiana. This is similar to the range found within natural populations of D. melanogaster. It was possible to derive a Thr-Gly “allele” of one species from that of another by invoking hypothetical Thr-Gly intermediates. A phylogeny based on the more conserved flanking sequences was produced. The results highlighted some of the problems which are encountered when highly polymorphic genes are used to infer phylogenies of closely related species.
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  • 20
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    Journal of molecular evolution 32 (1991), S. 421-428 
    ISSN: 1432-1432
    Keywords: Alcohol dehydrogenase ; Amino acid sequence ; Phylogenetic relationships ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Increasing data onDrosophila alcohol dehydrogenase (ADH) sequences have made it possible to calculate the rate of amino acid replacement per year, which is 1.7×10−9. This value makes this protein suitable for reconstructing phylogenetic relationships within the genus for those species for which no molecular data are available such asScaptodrosophila. The amino acid sequence ofDrosophila lebanonensis is compared to all of the already knownDrosophila ADHs, stressing the unique characteristic features of this protein such as the conservation of an initiating methionine at the N-terminus, the unique replacement of a glycine by an alanine at a very conserved position in the NAD domain of all dehydrogenases, the lack of a slowmigrating peptide, and the total conservation of the maximally hydrophilic peptide. The functional significance of these features is discussed. Although the percent amino acid identity of the ADH molecule inDrosophila decreases as the number of sequences compared increases, the conservation of residue type in terms of size and hydrophobocity for the ADH molecule is shown to be very high throughout the genusDrosophila. The distance matrix and parsimony methods used to establish the phylogenetic relationships ofD. lebanonensis show that the three subgenera,Scaptodrosophila, Drosophila, andSophophora separated at approximately the same time.
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  • 21
    ISSN: 1432-1432
    Keywords: Drosophila ; dec-1 locus ; Restriction map conservation ; Sequence comparison ; Melanogaster species subgroup ; Phylogeny
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    Notes: Summary We have analyzed ∼18 kb of DNA in and upstream of thedefective chorion-1 (dec-1) locus of the eight known species of themelanogaster species subgroup ofDrosophila. The restriction maps ofD. simulans, D. mauritiana, D. sechellia, D. erecta, andD. orena are shown to have basically the restriction map ofD. melanogaster, whereas the maps ofD. teissieri andD. yakuba were more difficult to align. However, the basic amount of DNA and sequence arrangement appear to have been conserved in these species. A small deletion of varying length (65–200 bp) is found in a repeated sequence of the central transcribed region ofD. melanogaster, D. simulans, andD. erecta. Restriction site mapping indicated that thedec-1 gene is highly conserved in themelanogaster species subgroup. However, sequence comparison revealed that the amount of nucleotide and amino acid substitution in the repeated region is much larger than in the 5′ translated region. The 5′ flanking region showed noticeable restriction site polymorphisms between species. Based on calculations from the restriction maps a dendrogram was derived that supports earlier published phylogenetic relationships within themelanogaster species subgroup except that theerecta-orena pair is placed closer to themelanogaster complex than toD. teissieri andD. yakuba.
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  • 22
    ISSN: 1432-1432
    Keywords: Drosophila ; Mariner ; Transposable elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The abundance of the transposable elementmariner differs dramatically in the genomes of the closely related speciesDrosophila simulans, D. mauritiana, D. sechellia, andD. melanogaster. Natural populations ofD. simulans andD. mauritiana have 1–10 and 20–30 copies per diploid genome, respectively, and the insertion sites are polymorphic. The element has not been found inD. melanogaster. In this paper we show thatD. sechellia, a species endemic to the Seychelles Islands, contains only twomariner elements that are at fixed sites in the genome. One element, inserted in chromosome 2R at 51A1–2, contains three deletions and is missing much of the 3′ end. The other element, inserted in chromosome 3L at 64A10–11, is the full length of 1286 bp. Although the sequence of the full-length element is polymorphic in populations ofD. sechellia, at least some of the sequences are closely related to elements fromD. simulans andD. mauritiana that are known to be active. However, judging from the progeny of crosses betweenD. sechellia andD. simulans, the biological activity of the full-lengthD. sechellia element appears to be low, either because of the nucleotide sequence of the element or because of its position in the genome, or both.
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  • 23
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    Journal of molecular evolution 34 (1992), S. 130-140 
    ISSN: 1432-1432
    Keywords: Drosophila ; Sophophora ; cDNA-DNA hybridization ; Phylogenetics
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    Topics: Biology
    Notes: Summary We have performed DNA-DNA hybridization experiments among several species of Drosophila using the evolutionarily conserved portion of the genome representing sequences coding for amino acids of proteins. This was done by using as tracer, radioactively labeled complementary DNA that was reverse transcribed from adult mRNA. We show that this procedure extends phylogenetically the distance over which the technique can be applied to fast-evolving groups such as Drosophila. The major phylogenetic conclusions are (1) the subgenus Sophophora is a monophyletic lineage; (2) within Sophophora the melanogaster subgroup is closer to the obscura group than either group is to the willistoni group; (3) the subgenus Drosophila is complex with most major lineages originating deep in the phylogeny; the subgenus may not be monophyletic; (4) as with most groups classically placed in Drosophila, the Hawaiian Drosophila originate early, supporting the notion that this lineage is older than the extant islands; and (5) the virilis/repleta lineage is monophyletic within Drosophila.
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  • 24
    ISSN: 1432-1432
    Keywords: Gene structure ; Heat shock ; hsp70 ; Antiparallel ORFs ; Drosophila
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    Notes: Abstract A clone isolated from a Drosophila auraria heat-shock cDNA library presents two long, antiparallel, coupled (LAC) open reading frames (ORFs). One strand ORF is 1,929 nucleotides long and exhibits great identity (87.5% at the nucleotide level and 94% at the amino acid level) with the hsp70 gene copies of D. melanogaster, while the second strand ORF, in antiparallel in-frame register arrangement, is 1,839 nucleotides long and exhibits 32% identity with a putative, recently identified, NAD+-dependent glutamate dehydrogenase (NAD+-GDH). The overlap of the two ORFs is 1,824 nucleotides long. Computational analysis shows that this LAC ORF arrangement is conserved in other hsp70 loci in a wide range of organisms, raising questions about possible evolutionary benefits of such a peculiar genomic organization.
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  • 25
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    Journal of molecular evolution 32 (1991), S. 454-462 
    ISSN: 1432-1432
    Keywords: Alcohol dehydrogenase gene ; Drosophila ; Gene structure ; Evolutionary trends ; Nucleotide substitution rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The study of individual genes is essential to a comprehensive understanding of genome evolution. The wealth of information on alcohol dehydrogenase (Adh) inDrosophila makes this gene particularly suitable for such analysis. We have characterized more than 4 kb of the genomicAdh region inDrosophila ambigua and compared this region toDrosophila mauritiana andDrosophila pseudoobscura. The presence of two genes,Adh and 3′ORF (open reading frame), has been confirmed and some of their essential features have been inferred from primary structural analysis. Inter- and intraspecific comparisons have led us to support that both genes may have diverged from an ancient precursor. They appear to be evolving independently, and show a species-specific pattern. TheAdh in theobscura group species lacks amino acids three and four when compared to the species of themelanogaster group and has accumulated most of its amino acid replacements in the third exon. Neither characteristic is observed when any other group species are compared, which suggests that these may be particular features of the evolution of theobscura group. The 3′ORF is highly conserved among the three species analyzed, although variability in the length of the third exon and the nucleotide substitution rate, which is much higher than inAdh, are worth noting. According to our data, both mutation/fixation rates and the distribution of mutations vary over time, which makes it difficult to predict the evolutionary dynamics of specific genome regions.
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  • 26
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    Journal of molecular evolution 33 (1991), S. 514-524 
    ISSN: 1432-1432
    Keywords: Drosophila ; Zaprionus ; Mariner ; Transposable elements ; Horizontal gene transfer ; Alcohol dehydrogenase (Adh) ; Sequence divergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The transposable element mariner occurs widely in themelanogaster species group ofDrosophila. However, in drosophilids outside of themelanogaster species group, sequences showing strong DNA hybridization with mariner are found only in the genusZaprionus. the mariner sequence obtained fromZaprionus tuberculatus is 97% identical with that fromDrosophila mauritiana, a member of themelanogaster species subgroup, whereas a mariner sequence isolated fromDrosophila tsacasi is only 92% identical with that fromD. mauritiana. BecauseD. tsacasi is much more closely related toD. mauritiana than isZaprionus, the presence of mariner inZaprionus may result from horizontal transfer. In order to confirm lack of a close phylogenetic relationship between the genusZaprionus and themelanogaster species group, we compared the alcohol dehydrogenase (Adh) sequences among these species. The results show that the coding region of Adh is only 82% identical betweenZ. tuberculatus andD. mauritiana, as compared with 90% identical betweenD. tsacasi andD. mauritiana. Furthermore, the mariner gene phylogeny obtained by maximum likelihood and maximum parsimony analyses is discordant with the species phylogeny estimated by using the Adh genes. The only inconsistency in the mariner gene phylogeny is in the placement of theZaprionus mariner sequence, which clusters with mariner fromDrosophila teissieri andDrosophila yakuba in themelanogaster species subgroup. These results strongly suggest horizontal transfer.
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  • 27
    ISSN: 1432-1432
    Keywords: Drosophila ; Two-dimensional electrophoresis ; Gonadal protein divergence ; Postzygotic reproductive isolation ; Speciation ; Hybrid sterility
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    Notes: Abstract The possible association between gonadal protein divergence and postzygotic reproductive isolation was investigated among species of the Drosophila melanogaster and D. virilis groups. Protein divergence was scored by high-resolution two-dimensional electrophoresis (2DE). Close to 500 protein spots from gonadal tissues (testis and ovary) and nongonadal tissues (malpighian tubules and brain) were analyzed and protein divergence was calculated based on presence vs absence. Both testis and ovary proteins showed higher divergence than nongonadal proteins, and also a highly significant positive correlation with postzygotic reproductive isolation but a weaker correlation with prezygotic reproductive isolation. Particularly, a positive and significant correlation was found between proteins expressed in the testis and postzygotic reproductive isolation among closely related species such as the within-phylad species in the D. virilis group. The high levels of male-reproductive-tract protein divergence between species might be associated with F1 hybrid male sterility among closely related species. If so, a lower level of ovary protein divergence should be expected on the basis that F1 female hybrids are fully fertile. However, this is not necessarily true if relatively few genes are responsible for the reproductive isolation observed between closely related species, as recent studies seem to suggest. We suggest that the faster rate of evolution of gonadal proteins in comparison to nongonadal proteins and the association of that rate with postzygotic reproductive isolation may be the result of episodic and/or sexual selection on male and female molecular traits.
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  • 28
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    Journal of molecular evolution 41 (1995), S. 615-621 
    ISSN: 1432-1432
    Keywords: Drosophila ; Ribosomal genes ; Sequence data
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    Notes: Abstract We compare the 5S gene structure from nine Drosophila species. New sequence data (5S genes of D. melanogaster, D. mauritiana, D. sechellia, D. yakuba, D. erecta, D. orena, and D. takahashii) and already-published data (5S genes of D. melanogaster, D. simulans, and D. teissieri) are used in these comparisons. We show that four regions within the Drosophila 5S genes display distinct rates of evolution: the coding region (120 bp), the 5′-flanking region (54–55 bp), the 3′-flanking region (21–22 bp), and the internal spacer (149–206 bp). Intra- and interspecific heterogeneity is due mainly to insertions and deletions of 6–17-bp oligomers. These small rearrangements could be generated by fork slippages during replication and could produce rapid sequence divergence in a limited number of steps.
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  • 29
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    Journal of comparative physiology 176 (1995), S. 355-364 
    ISSN: 1432-1351
    Keywords: Drosophila ; Giant fiber ; Escape Olfactory ; Flight
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    Topics: Biology , Medicine
    Notes: Abstract We have monitored the patterns of activation of five muscles during flight initiation of Drosophila melanogaster: the tergotrochanteral muscle (a mesothoracic leg extensor), dorsal longitudinal muscles #3, #4 and #6 (wing depressors), and dorsal ventral muscle #Ic (a wing elevator). Stimulation of a pair of large descending interneurons, the giant fibers, activates these muscles in a stereotypic pattern and is thought to evoke escape flight initiation. To investigate the role of the giant fibers in coordinating flight initiation, we have compared the patterns of muscle activation evoked by giant fiber stimulation with those during flight initiations executed voluntarily and evoked by visual and olfactory stimuli. Visually elicited flight initiations exhibit patterns of muscle activation indistinguishable from those evoked by giant fiber stimulation. Olfactory-induced flight initiations exhibit patterns of muscle activation similar to those during voluntary flight initiations. Yet only some benzaldehyde-induced and voluntary flight initiations exhibit patterns of muscle activation similar to those evoked by giant fiber stimulation. These results indicate that visually elicited flight initiations are coordinated by the giant fiber circuit. By contrast, the giant fiber circuit alone cannot account for the patterns of muscle activation observed during the majority of olfactory-induced and voluntary flight initiations.
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  • 30
    ISSN: 1432-1351
    Keywords: Ligand-gated channel ; Chloride channel ; Histamine ; Drosophila ; Visual ecology
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    Topics: Biology , Medicine
    Notes: Abstract The large monopolar cells (LMCs) of the first optic neuropil (lamina) in insects respond to the photoreceptor neurotransmitter histamine with an increase in chloride conductance. We have compared the properties of this conductance from a range of diptera from different visual environments: Tipula paludosa (slow flying, crepuscular), Drosophila melanogaster (slow-flying diurnal), and 3 fast-flying diurnal species Musca domestica, Calliphora vicina and Lucilia sericata. In whole-cell recordings of dissociated LMCs, histamine-induced currents were elicited using a multichannel parallel perfusion device, allowing rapid determination of the dose-response function, characterised by affinity (K d) and Hill coefficient (n). Calliphora, Lucilia and Musca had the steepest dose response curves (n = 2.8) and the lowest affinity for histamine (K d 35–50 μM); the crepuscular Tipula had a significantly higher affinity (K d = 16 μM) and lower Hill coefficient (n = 1.8). Drosophila had a high affinity (K d 24 μM), and a high Hill coefficient (n = 2.5). In excised inside-out patch recordings all species showed similar single channel properties (conductance 40–60 pS, mean open time 〈 1 ms). The low Hill coefficient in Tipula would be expected to result in lower synaptic gain. We suggest this may be an adaptation to prevent the LMC's response bandwidth being filled with the high levels of photon noise typical of photoreceptors adapted for low light levels. The lower affinity for histamine found in the more photopic species suggests that the concentration of histamine (and therefore presumably number of synaptic vesicles released from the photoreceptors) should be higher. This might improve signal-to-noise ratio by decreasing the contribution of the shot event noise introduced by stochastic release of synaptic vesicles.
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  • 31
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    Journal of comparative physiology 170 (1992), S. 311-316 
    ISSN: 1432-1351
    Keywords: Phototransduction ; Limulus polyphemus ; Inositol trisphosphate ; Calcium ; Latency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The latent period before depolarization of Limulus ventral photoreceptors by light flashes was compared with that following brief, intracellular, pressure-injection of d-myo-inositol 1,4,5 trisphosphate. At temperatures between 18 °C and 22 °C and with an extracellular calcium concentration of 10 mM, the responses of 4 cells to light and to injections of 100 μM inositol trisphosphate displayed average latencies of 71 and 56 ms, respectively. The latencies of responses to InsP3 included an estimated 20 ms dead-time inherent in the injection method. Reducing the temperature lengthened the latency of the response to light (Q10 approximately 3.2 between 7 and 22 °C) more than that to inositol trisphosphate (Q10 approximately 2.3). Bathing the photoreceptors in seawater containing no added calcium and 1 mM of the calcium chelator EGTA greatly increased the latency of the light response at all temperatures, but did not increase the latency of the response to inositol trisphosphate. We conclude that the response to inositol trisphosphate lacks the calcium- and temperature-sensitive latent period which characterizes the response to light. If inositol trisphosphate acts, via the release of stored calcium, to stimulate an intermediate in the visual cascade, then that intermediate would appear to be downstream from the latency-generating mechanism.
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  • 32
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    Journal of comparative physiology 171 (1992), S. 413-419 
    ISSN: 1432-1351
    Keywords: Calcium ; Cobalt ; Lateral line ; Behavior
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    Topics: Biology , Medicine
    Notes: Summary The hypothesis that the blind cave fish (Astyanax hubbsi) adjusts the level of stimulation to its lateral line system (LLS) by varying its own velocity was examined. When the sensitivity of the LLS sense organs was reduced by lowering the Ca2+ concentration in the water or by adding Co2+ the fish compensated for this by swimming at a higher velocity.
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  • 33
    ISSN: 1432-1351
    Keywords: Ligand-gated channel ; Chloride channel ; Histamine ; Drosophila ; Visual ecology
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    Topics: Biology , Medicine
    Notes: Abstract The large monopolar cells (LMCs) of the first optic neuropil (lamina) in insects respond to the photoreceptor neurotransmitter histamine with an increase in chloride conductance. We have compared the properties of this conductance from a range of diptera from different visual environments:Tipula paludosa (slow flying, crepuscular),Drosophila melanogaster (slow-flying diurnal), and 3 fast-flying diurnal speciesMusca domestica,Calliphora vicina andLucilia sericata. In whole-cell recordings of dissociated LMCs, histamine-induced currents were elicited using a multichannel parallel perfusion device, allowing rapid determination of the dose-response function, characterised by affinity (K d) and Hill coefficient (n).Calliphora,Lucilia andMusca had the steepest dose response curves (n = 2.8) and the lowest affinity for histamine (K d 35–50 μM); the crepuscularTipula had a significantly higher affinity (K d = 16 μM) and lower Hill coefficient (n = 1.8).Drosophila had a high affinity (K d 24 μM), and a high Hill coefficient (n = 2.5). In excised inside-out patch recordings all species showed similar single channel properties (conductance 40–60 pS, mean open time 〈 1 ms). The low Hill coefficient inTipula would be expected to result in lower synaptic gain. We suggest this may be an adaptation to prevent the LMC's response bandwidth being filled with the high levels of photon noise typical of photoreceptors adapted for low light levels. The lower affinity for histamine found in the more photopic species suggests that the concentration of histamine (and therefore presumably number of synaptic vesicles released from the photoreceptors) should be higher. This might improve signal-to-noise ratio by decreasing the contribution of the shot event noise introduced by stochastic release of synaptic vesicles.
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  • 34
    ISSN: 1432-1432
    Keywords: Drosophila ; per gene ; Repeated sequence ; Threonine-glycine ; Length polymorphism ; Minisatellite
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    Topics: Biology
    Notes: Summary Single-fly polymerase chain reaction amplification and direct DNA sequencing revealed high levels of length polymorphism in the threonine-glycine encoding repeat region of theperiod (per) gene in natural populations ofDrosophila melanogaster. DNA comparison of two alleles of identical lengths gave a high number of synonymous substitutions suggesting an ancient time of separation. However detailed examination of the sequences of different Thr-Gly length variants indicated that this divergence could be understood in terms of four deletion/insertion events. InDrosophila pseudoobscura a length polymorphism is observed in a five-amino acid degenerate repeat, which corresponds tomelanogaster's Thr-Gly domain. In spite of the differences betweenD. melanogaster andD. pseudoobscura in the amino acid sequence of the repeats, the predicted secondary structures suggest evolutionary and mechanistic constraints on theper protein of these two species.
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  • 35
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    Journal of molecular evolution 16 (1980), S. 37-46 
    ISSN: 1432-1432
    Keywords: Evolution ; Drosophila ; Temperature ; Mitochondrial enzymes ; Kinetic properties
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The evolutionary behavior of two mitochondrial enzymes (L-glycerol 3-phosphate:cytochrome c oxidoreductase E.C.1.1.1.95,αGPO, and L-malate: NAD+ oxidoreductase, E.C.1.1.1.37, m-MDH) obtained from several temperate and tropicalDrosophila species was examined by comparing their catalytic properties, which related to temperature (Km-Ea-Q10-Thermostability). MitochondrialαGPO or m-MDH obtained either from temperate or from tropical species was found to exhibit similar catalytic properties while for both cytosolic enzymes, theαGPDH and s-MDH, Km patterns were similar among species from the same thermal habitat and different between thermal habitats. In combination with other observations reported in the literature these facts support the view that the function, and probably the structure, of mitochondrial enzymes are better conserved in evolution than those of the corresponding enzymes found in the cytosol. It is proposed that the relative invariance of the mitochondrial enzymes structure is probably linked to a necessary relative invariance of molecular interactions inside the mitochondrion.
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  • 36
    ISSN: 1432-2285
    Keywords: Calcium ; Barium ; Manganese ; Strontium ; Picea abies needles
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    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The concentrations of Ca, Sr, Ba and Mn were determined in up to five successive needle age classes from 54 individual Norway spruce trees [Picea abies (L.) Karst] from nine different sites. The accumulation behaviour was found to be very nonuniform, going from an increase with needle age to a decrease; irregular patterns were also found. The type of accumulation is largely site specific. The increasing behaviour can in most cases be approximated by a simple arithmetic function. All four elements usually show the same accumulation pattern, the similarities being closest between Ca and Mn and least between Ca and Ba. It is postulated that the similarity between the four elements is due to their precipitation and storage as oxalates. The similarity between Ca, Sr and Ba is observed at all concentrations, that with Mn only at concentrations larger than 300 μg/g. Mn at small concentrations (〈 50 μg/g) shows a decreasing pattern and no similarity at all with Ca, Sr and Ba, but behaves similar to mobile elements.
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  • 37
    ISSN: 1423-0127
    Keywords: T cell ; Cell Tak® ; Calcium ; Superfusion ; Spectrofluorometer ; Confocal microscopy ; Concanavalin A ; Isoproterenol
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    Topics: Biology , Medicine
    Notes: Abstract Mitogen- and isoproterenol-induced changes of [Ca2+]i in T cells attached to a glass substrate were examined. Murine (C57BL/6) splenic T cells were attached to coverslips or 35-mm dishes (MatTek) precoated with Cell Tak® (3.5 µg/cm2). The cells were then loaded with fluorescent dye (2 µg/ml of fura2-AM or fluo3-AM) and changes in [Ca2+]i in a population of cells (using a spectrofluorometer) or in single cells (using a confocal microscope) were measured during continuous superfusion. Population measurements of [Ca2+]i demonstrated that concanavalin A (Con A, 2 or 5 µg/ml) caused an increase in [Ca2+]i that rose to a peak and then declined to a steady state. The concentration-response relationship (0.05–5 µg/ml) had an EC50 of ∼0.3 µg/ml. Isoproterenol decreased the Con A-induced elevation of steady state [Ca2+]i. In single cell studies, the increase in [Ca2+]i in response to Con A typically occurred in about 50% of the cells in a microscope field, and the delay before activation varied among cells. Taken together, these data demonstrate that Cell Tak® can be used to attach T cells to glass coverslips and will be useful for the study of signaling mechanisms in T cells.
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  • 38
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    Development genes and evolution 188 (1980), S. 55-63 
    ISSN: 1432-041X
    Keywords: Drosophila ; Compound eye ; shibire ts ; Development
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    Topics: Biology
    Notes: Summary We have analysed the effect of temperature on both developing and adult eye cell clones homozygous forshi ST139, a temperature-sensitive mutant ofDrosophila melanogaster. The mutant gene, autonomous in its cellular expression, causes structural modifications of ommatidial cells when adult clones of cells are exposed to the restrictive temperature (29°C) for several days. However, the mutant phenotype reverses to normal within 4 days at the permissive temperature (20°C). The results of pulse, shift-up and shift-down experiments show that the temperaturesensitive period for developing compound eye cells is from the late second instar up to the early pupa. Cytodifferentiation of compound eye cells is blocked by restrictive temperature treatment during this period, whereas cell proliferation does not seem to be directly affected. These results are discussed with regard to the other known aspects of the phenotype observed in mutant individuals.
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  • 39
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    Development genes and evolution 192 (1983), S. 164-170 
    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal disc ; Morphogenesis ; Tissue culture
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    Topics: Biology
    Notes: Summary The early morphogenesis of the eye-antennal disc ofDrosophila in response to 20-hydroxy ecdysone involves the curling of the eye anlagen dorsally over the antenna. During this process, the area of the peripodial membrane is substantially reduced. The peripodial membrane is taut at this stage, and if it is cut the curling of the disc cannot continue, and the eye anlagen returns to its original position within one minute of the operation. In contrast, cutting the columnar epithelium between the eye and antennal anlagen does not disrupt curling, but actually facilitates it. During curling, the cells of the peripodial membrane appear healthy, and exhibit basal extensions. We suggest that the curling of the eye is mediated by the conversion of cuboidal peripodial membrane cells into pseudostratified columnar epithelium at the edges of the peripodial membrane. Subsequently, cells of the peripodial membrane secrete first a pupal cuticle, and then an imaginal cuticle.
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  • 40
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    Development genes and evolution 192 (1983), S. 275-279 
    ISSN: 1432-041X
    Keywords: Evagination ; Morphogenesis ; Metamorphosis ; Female genital disc ; Drosophila
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    Topics: Biology
    Notes: Summary The morphology of the evaginating female genital disc ofDrosophila melanogaster was examined at different stages of metamorphosis. The observations show that the internal genital organs are derived from the anterior half of the disc and that their morphogenesis is mainly a protrusion of the different primordial areas of the disc epithelium. The external genital and anal derivatives originate from the posterior half of the disc, which undergoes complex rearrangements during metamorphosis. The disc opens along the posterior margin and the dorsal and ventral epithelia evert and thereby completely reverse their anteroposterior orientation. Dramatic elongation has been observed during the formation of the seminal receptacle. The cells of the repressed male genital primordium do not form any recognizable structures and are assumed to be eliminated during metamorphosis.
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  • 41
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    Development genes and evolution 192 (1983), S. 299-302 
    ISSN: 1432-041X
    Keywords: Differentiation ; Teratogens ; Drosophila ; 5-Azacytidine ; Methylation
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    Topics: Biology
    Notes: Summary The effects of cytidine and cytidine analogs were studied inDrosophila embryonic cell cultures and two wild-type established cell lines, Oregon-R and Schneider line 2. Primary embryonic cultures have been shown to be an excellent system for the study of embryonic development; a number of cell types undergo normal differentiation in vitro. Treatment of these cultures with putative teratogens resulted in an inhibition of muscle and/or neuron differentiation in our study. Treatment of these cells with cytidine and seven other analogs had no effect on neuron and muscle differentiation. The compound 5-azacytidine, when added to primary cell cultures, inhibited normal differentiation at subtoxic doses while inducing the production of three proteins that comigrate with the heat-shock proteins, hsp 23, 22a and 22b. 5-Azacytidine did not stimulate differentiation in Oregon-R or SchneiderDrosophila cell lines. The in vitro blockage of differentiation by 5-azacytidine suggests that it may act as a teratogen.
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  • 42
    ISSN: 1432-041X
    Keywords: Drosophila ; Head development ; Segmentation mutants ; Nervous system ; Optic lobe
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    Topics: Biology
    Notes: Abstract We describe the development of 20 sensory organs in the embryonic Drosophila head, which give rise to 7 sensory nerves of the peripheral nervous system (PNS), and 4 ganglia of the stomatogastric nervous system (SNS). Using these neural elements and the optic lobes as well as expression domains of the segment polarity gene engrailed in the wild-type head of Drosophila embryos as markers we examined the phenotype of different mutants which lack various and distinct portions of the embryonic head. In the mutants, distinct neural elements and engrailed expression domains, serving as segmental markers, are deleted. These mutants also affect the optic lobes to various degrees. Our results suggest that the optic lobes are of segmental origin and that they derive from the ocular segment anteriorly adjacent to the antennal segment of the developing head.
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  • 43
    ISSN: 1420-9071
    Keywords: Aromatic plants ; essential oils ; Drosophila ; insecticides
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    Topics: Biology , Medicine
    Notes: Abstract Effects of the essential oils (EOs) extracted from eleven aromatic plants belonging to the Lamiaceae family (common in the Greek flora) were examined upon three different developmental stages ofDrosophila auraria. All of the EOs examined exhibited insecticidal effects, either by preventing egg hatching, or by causing the death of larvae and adult flies. In several cases, malformation and/or prohibition of puparium formation was also observed.
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  • 44
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    Development genes and evolution 192 (1983), S. 280-284 
    ISSN: 1432-041X
    Keywords: Evagination ; Morphogenesis ; Metamorphosis ; Intersexual genital disc ; Drosophila
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    Topics: Biology
    Notes: Summary Morphogenetic movements of the intersexual genital disc of thedoublesex-dominant mutant ofDrosophila melanogaster were followed during metamorphosis. Intersexual genital discs contain well developed genital primordia of both sexes as well as an anal primordium, and all of these primordia evaginate simultaneously. The female genital primordium is deflected to the ventral side by the male genital primordium which is located anterior to it. Subsequently the anterior parts of the two genital primordia project their internal appendages in parallel in the anterior direction. The morphogenetic movements closely resemble those of the corresponding parts of normal males and females. The disc opens at the stalk along the posterior edge and the two genital primordia completely evert their posterior parts. These areas undergo complex rearrangements whereby the anlage for the male genital arch as well as that for the 8th tergite evert and move around the lateral side of the disc. They both fuse dorsally after enclosing the anal tube. The formation of the characteristic abnormalities of the intersexual genitalia seems not to result simply from spatial problems of the simultaneous evagination of the genital anlagen but rather to be a direct result of the ambiguous genetic signalling in the intersexual cells of these primordia.
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  • 45
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    Development genes and evolution 192 (1983), S. 337-346 
    ISSN: 1432-041X
    Keywords: Drosophila ; Gynandromorphs ; Genital disc ; Compartments ; Evolution
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    Topics: Biology
    Notes: Summary The genital imaginal disc ofDrosophila differentiates the terminalia, i.e. the genitalia and analia, of both sexes. It represents a composite anlage, containing a female genital primordium, a male genital primordium and an anal primordium. In normal males and females, only one of the two genital primordia differentiates; the other is developmentally repressed. Therefore, cell-lineage relationships between the male and female genital primordia can only be studied in sexual mosaics which differentiate female and male cells. We producedMinute (M)‖non-Minute(M+) gynandromorphs and selected those with sexually mosaic terminalia for a cell-lineage analysis. In these mosaics, either the male (XO) or female (XX) cells wereM + and thus had a growth advantage. The differential growth rates served as a tool to detect clonal restrictions. In control gynandromorphs (M +‖M +), the amount of female genitalia differentiated was largely independent of the amount of male genitalia present. In contrast, male and female anal structures, as a rule, added up to one full set. The same was true for the experimentalM‖M + gynandromorphs, but the contribution ofXX andXO cells to mosaic terminalia changed drastically due toM + cells competing successfully against the more slowly growingM cells. Specific subsamples ofM‖M + gynandromorphs showed thatM cells in a non-mosaic primordium are shielded from cell competition taking place in the neighbouring mosaic primordium. We conclude that the three primordia of the genital disc represent developmental compartments. In the genital primordia, even developmentally repressedM + cells compete successfully against developmentally activeM cells.
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  • 46
    ISSN: 1432-041X
    Keywords: Muscle ; Salivary glands ; Gut ; Programmed cell death ; Steroid hormones ; Drosophila
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    Topics: Biology
    Notes: Summary In holometabolous insects, the steroid molting hormone 20-OH-ecdysone (ecdysterone) orchestrates the diverse developmental events of metamorphosis, in large part by regulating gene expression. In Drosophila, the Broad Complex (BR-C) is one of the first loci to be induced by ecdysterone at the end of larval life, and is essential for translating the hormonal signal into the behavioral and anatomical events which herald the onset of metamorphosis. BR-C products are believed to act by binding to and modifying the transcriptional activities of other hormone-sensitive genes. In addition to abnormalities of the epidermis, BR-C mutants dying during metamorphosis manifest a syndrome of multiple internal tissue defects which represent a failure of the larval-to-adult transition. We have reported features of central nervous system metamorphosis requiring BR-C function, notably morphogenetic movements and optic lobe organization. In this paper we describe defective development of salivary glands, flight muscles, and gut in BR-C mutants, including: persistence of larval salivary glands; failure of the adult salivary glands to extend into the thorax; abnormalities of midgut transition and of proventriculus structure and location; and absence of dorsal-ventral indirect flight muscles. Some of these abnormalities represent defects in programmed cell death. Distinct patterns of phenotypes were seen in mutants of each of the three lethal complementation groups comprising the BR-C. The patterns of phenotypes suggest overlapping but distinct functions encoded by this complex locus.
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  • 47
    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal discs ; Pattern formation ; rotund
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    Notes: Summary InDrosophila imaginal discs, pattern formation requires the activity of three positional information systems, antero-posterior (A/P), dorso-ventral (D/V) and proximo-distal (P/D). Three genes,Decapentaplegic, Distal-less androtund (rn), involved in pattern formation along the P/D axis have been characterized. Thern gene is required in a sub-distal region, localized at a similar position along the P/D axis in all appendages; it encodes two major transcripts, m1.7 and m5.3, both expressed in the central region of all the major imaginal discs. The present study of these transcripts in severalrn mutant favours m5.3 as encodingrn morphogenetic function in the imaginal discs. The fine characterization of its distribution partitions all major imaginal discs in domains along the P/D axis. The ventral and dorsal discs appear to be similarly but not identically organized: two P/D domains are evident in the wing and haltere discs whilst the leg and antenna discs appear to be composed of at least three. We also show that m5.3 is sex-regulated in the genital disc and thatrn function is required for proper development of a sub-distal structure of the female genitalia. This suggests that the primordia of the female genitalia may be organized in a similar way to the other imaginal discs, and strongly supports the hypothesis thatrn function is specific to pattern formation along the P/D axis and that it may be involved in the establishment or maintenance of this pattern.
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  • 48
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    Development genes and evolution 201 (1992), S. 364-375 
    ISSN: 1432-041X
    Keywords: Drosophila ; Tissue culture ; In vitro ; Invertebrate embryogenesis
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    Topics: Biology
    Notes: Summary We have devised techniques to culture whole, dissected embryos of Drosophila melanogaster. We examine multiple aspects of the morphological and physiological development of the epidermis, musculature, nervous system, and internal organs in this cultured preparation, and show that in vitro development closely parallels normal embryogenesis. These techniques permit a wide range of experimental manipulations during embryogenesis and allow us to extend observations through late embryonic stages, after cuticle deposition. Applications of this technique are presented.
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  • 49
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    Development genes and evolution 205 (1995), S. 62-72 
    ISSN: 1432-041X
    Keywords: Antennal lobe ; Cell division ; euroblasts ; BrdU incorporation ; Drosophila
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    Topics: Biology
    Notes: Abstract The adult antennal lobe of Drosophila melanogaster emerges from a precursor, the larval antennal lobe. Pulse and pulse-chase labelling of dividing cells in larvae and pupae with bromodeoxyuridine confirmed previous data that some of the interneurons of the adult antennal lobe derive from a lateral neuroblast which starts to divide early in the first larval instar. However, the majority of these interneurons originate from neuroblasts that initiate mitosis at later stages, with a peak of about 10–12 pairs of dividing neuroblasts in the late third larval instar. No clustering of adult antennal lobe neurons according to their birthdates was observed. In contrast to neurons, terminal divisions of glia in the antennal lobe reach their maximum only 12 h after puparium formation.
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  • 50
    ISSN: 1432-041X
    Keywords: Brachyury ; Trg ; Hindgut ; Proctodeum ; Drosophila
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    Notes: Abstract The proctodeum of the Drosophila embryo originates from the posterior end of the blastoderm and forms the hindgut. By enhancer-trap mutagenesis, using a P-element-lacZ vector, we identified a mutation that caused degeneration of the proctodeum during shortening of the germ band and named it aproctous (apro). Expression of the lacZ reporter gene, which was assumed to represent expression of the apro gene, began at the cellular blastoderm stage in a ring that encompassed about 10–15% of the egg's length (EL) and included the future proctodeum, anal pads, and posterior-most part of the visceral mesoderm. In later stages, strong expression of lacZ was detected in the developing hindgut and anal pads. Expression continued in the anal pads and epithelium of the hindgut of larvae; the epithelium of the hindgut of the adult fly also expressed lacZ. The spatial patterns of the expression of lacZ in various mutants suggested that the embryonic expression of apro was regulated predominantly by two gap genes, tailless (tll) and huckebein (hkb): tll is necessary for the activation of apro, while hkb suppressed the expression of apro in the region posterior to 10% EL. Cloning and sequencing of the apro cDNA revealed that apro was identical to the T-related gene (Trg) that is a Drosophila homolog of the vertebrate Brachyury gene. apro appears to play a key role in the development of tissues derived from the proctodeum.
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  • 51
    ISSN: 1432-041X
    Keywords: Drosophila ; Mini-white reporter gene ; Teashirt ; Engrailed ; Wingless
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    Notes: Abstract Developmental expression of transduced mini-white(w) gene of Drosophila is sensitive to its flanking genomic enhancers. Taking advantage of this phenomenon, we mobilized a P lacW transposon and screened for new transposant lines which showed patterned expression of the mini-w gene in adult eyes. From a screen of about 1,000 independent P lacW transposant lines on the second chromosome, we identified 7 lines which showed patterned w expression in adult eyes. These P insertions were assigned to engrailed, wingless and teashirt genes based on their chromosomal locations, developmental expression of the lacZ reporter gene, lethal embryonic mutant phenotypes and, finally, their failure to complement the lethal alleles of the respective genetic loci. Our results show that although only a small fraction of the total transposant lines displayed patterned w expression, the genetic loci thus identified are those which play essential roles in pattern formation. Scopes of screens for genetic loci based on w reporter gene expression in adult eyes are discussed.
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  • 52
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    Development genes and evolution 188 (1980), S. 163-177 
    ISSN: 1432-041X
    Keywords: Yolk sac ; Ultrastructure ; Embryogenesis ; Drosophila
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    Topics: Biology
    Notes: Summary Changes at the ultrastructural level during germ band extension in the embryo ofDrosophila melanogaster are described. Cytoplasmic connections between cells and the yolk sac are present during initial cellular movements. At this time, a continuous system of microfilaments is present adjacent to the membranes in the connections and at the periphery of the yolk sac. As germ band extension progresses, this system becomes discontinuous, and microfilaments are apparent only in the immediate vicinity of the connections. Cytoplasmic connections are disassembled at approximately the midpoint of extension; at the same time, extensive membrane associations develop between germ band cells and between these cells and adjacent yolk sac membranes. Positioning and orientation of cytoplasmic connections suggest that the yolk sac, via these connections, is actively involved in the cellular movements of early germ band extension.
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  • 53
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    Development genes and evolution 189 (1980), S. 57-67 
    ISSN: 1432-041X
    Keywords: Drosophila ; Ecdysone deficient mutants ; Ecdysteroid titer ; Ring gland ; Fine structure
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    Notes: Summary This paper describes two ecdysone-deficient, recessive-lethal mutants,lethal(1)giant ring gland (grg) andlethal(1)suppressor of forked mad-ts (mad-ts: Jürgens and Gateff 1979) and compares their ecdysteroid titers with that of the wild-type. Mutant larvae show a much reduced ecdysteroid content, amounting to 1/10 to 1/30 of the wild-type values, but never a true titer peak. They fail to pupate and die after 1–3 weeks. Ecdysteroid feeding elicits different responses in the larvae of the two mutants.mad-ts larvae pupate within 24 h, thus showing that their low ecdysteroid titer is directly connected to their inability to pupate.mad-ts resembles the mutantlethal (3)ecdysone-1 ts (Garen et al. 1977). Thegrg mutant larvae, on the other hand, fail to pupate after 20-hydroxyecdysone feeding as well as injection. The primary defect of thegrg mutant is not entirely clear. Thegrg larval salivary gland cells appear to possess normal ecdysteroid receptors. Furthermore, the low ecdysteroid titer ingrg is not the result of an increased ecdysteroid catabolism. The primary defect in the mutant may lie in the malfunctioning neurosecretory cells which do not show neurosecretion in histological preparations. Further support for this notion comes from electronmicrographs of the enlargedgrg ring glands which, in contrast to the wild-type, do not possess nerve endings. In the wild-type three ecdysteroid peaks were found: one shortly before puparium formation, the second at approximately 12 h and the third at about 30 h after pupation. The ecdysteroid titer peak in late third instar, wild-type larvae is mainly due to the presence of 20-dydroxyecdysone as shown by radioimmunoassays after thin layer chromatography and derivatization followed by gas liquid chromatography and mass spectroscopy. In addition, a number of unidentified polar and apolar metabolites were also present.
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  • 54
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    Development genes and evolution 188 (1980), S. 157-161 
    ISSN: 1432-041X
    Keywords: Drosophila ; Imaginal discs ; Compartments ; Distal outgrowth
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    Topics: Biology
    Notes: Summary Peripheral tissue of the imaginal wing disc gives rise to the proximal mesothoracic structures of the adult. Pieces of peripheral tissue, which have no regenerative capacity when cultured as intact fragments, are capable of distal outgrowth (regeneration) after dissociation and reaggregation. This ability depends on the region of the disc periphery from which the fragment is taken. Extensive distal outgrowth occurs in reaggreages of a fragment containing equal proportions of tissue from anterior and posterior developmental compartments. The extent of outgrowth decreases as the proportion of posterior tissue is reduced, so that a fragment containing only anterior tissue shows no regeneration after dissociation. Limited distal outgrowth occurs in reaggregates of a wholly posterior fragment, but the regenerative capacity is increased greatly when a small amount of anterior tissue is included. It is concluded that distal outgrowth in the wing disc requires an interaction between cells of the anterior and posterior compartments.
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  • 55
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    Development genes and evolution 189 (1980), S. 91-96 
    ISSN: 1432-041X
    Keywords: Epimorphic regulation ; Drosophila ; Imaginal discs
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    Topics: Biology
    Notes: Summary It has been known for many years that when a wing disc ofDrosophila is bisected, and the fragments cultured in adult females, regulation occurs and either a complete disc is regenerated or the fragment is duplicated. We have investigated how this regeneration process occurs. To establish which cells contribute to the regenerate, and thus determine if regeneration is the result of epimorphic regulation, fragments of discs, after culture in an adult for one to five days, were exposed to3H-thymidine to label replicating cells. Imaginal discs, both whole and as regenerating fragments, undergo some DNA replication which is distributed throughout the disc, but cut discs frequently show clusters of labelled cells around the wound, indicating that regeneration is probably epimorphic.
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  • 56
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    Development genes and evolution 192 (1983), S. 48-50 
    ISSN: 1432-041X
    Keywords: Drosophila ; Hybrid lethality ; Imaginal discs ; Interspecific transplantation
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    Topics: Biology
    Notes: Summary Females ofDrosophila melanogaster, crossed with males ofDrosophila mauritiana, produce only female offspring. The male hybrid larvae grow very slowly, fail to pupate and die after prolonged larval life. Imaginal discs from these male hybrids transplanted into Drosophila melanogaster larvae can give rise to adult structures with normal patterns. Differentiation of hybrid imaginal disc tissue is improved by short term culture in non-hybrid larvae prior to metamorphosis, suggesting that the hybrid larval haemolymph is inadequate to sustain normal imaginal disc growth. This may represent the physiological basis of the reproductive isolating mechanism separating the twoDrosophila species
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  • 57
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    Development genes and evolution 192 (1983), S. 270-274 
    ISSN: 1432-041X
    Keywords: Fate map ; Repressed primordium ; Sex determination ; Genital disc ; Drosophila
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    Notes: Summary The female genital disc ofDrosophila melanogaster was cut into distinct fragments, and the prospective fates of the fragments were determined by putting them through metamorphosis in host larvae. The dorsal epithelium contains the anlagen for the anal plates and parovaria, as well as the repressed male genital primordium. The ventral epithelium gives rise to all of the female genital structures except for the parovaria. The results were compared with published fate maps and observations made in experiments with sex-transforming mutations. This allowed us to establish a detailed three-dimensional fate map of the female genital disc, which shows a well-developed female genital primordium in the ventral epithelium, a repressed male genital primordium in the anterior part of the dorsal epithelium and an anal primordium in the posterior region of the dorsal disc epithelium.
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  • 58
    ISSN: 1432-041X
    Keywords: Drosophila ; Cell degeneration ; Imaginal disc ; Basal lamina ; Blood cells
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    Notes: Summary The mutationsvestigial (vg; recessive) andUltravestigial (vg U; dominant) ofDrosophila melanogaster give rise to identical mutant adult phenotypes in which much of the cases this results from cell death in the presumptive wing margin of the wing disc in the third larval instar, but the process of cell degeneration is quite different in the two mutants. Invg cell death occurs continuously throughout the third larval instar, while invg U it occurs only in the early third instar. Cells fragment and some of the fragments condense, becoming electron dense (“apoptosis”). Both condensed and ultrastructurally normal cell fragments are extruded to the basal side of thevg disc epithelium. They accumulate under the basal lamina in the wing pouch area until they are phagocytosed by blood cells entering the wing pouch during the six hours following pupariation. Fragments are not extruded from thevg U epithelium but are apparently phagocytosed by neighboring epithelial cells. The basal lamina undergoes mophological changes following pupariation and is phagocytosed by blood cells in both wild-type andvestigial, but investigial the degenerated cell fragments are also engulfed by the same blood cells.
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  • 59
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    Development genes and evolution 192 (1983), S. 317-326 
    ISSN: 1432-041X
    Keywords: Neurogenic mutations ; Topological specificity ; Drosophila
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    Notes: Summary Neurogenic mutations have been found to cause the neuralization of certain regions of the ectoderm and yet to permit normal development of the remaining embryonic cells. Thus, it seems that the activity of the wild-type alleles of these genes is dispensable in a considerable fraction of the embryo during wild-type development. This effect might be a consequence of the cells' position within the embryo; alternatively, it might be independent of the position but be due rather to the genetic activity experienced by the cells previous to their commitment. The results described in this paper indicate that genes controlling patterning along the embryonic dorso-ventral perimeter (dorsal and Toll) are epistatic to genes controlling neurogenesis, their activity deciding which ectodermal cells are susceptible to neurogenesis. Using alleles with low expressivity, evidence was obtained showing that the tracheal placodes define the boundary of the territory which has neurogenic abilities at thoracic and abdominal levels.
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  • 60
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    Development genes and evolution 201 (1992), S. 105-112 
    ISSN: 1432-041X
    Keywords: Drosophila ; Genital disc ; tra-2 ts ; Differentiation
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    Notes: Summary Diplo-X flies homozygous for the transform-er-2 ts (tra-2 ts) mutation develop into females at 16° C, while they develop into males at 29° C (Belote and Baker 1982). By means of this conditional mutation, we have carried out a detailed analysis of the development of the genital disc. Temperature shifts between 16 and 29° C, in both directions, and temperature pulses at 29° C, have been applied during the larval growth of tra-2 ts homozygous diplo-X flies, and the external derivatives of the genital disc have been analysed. Genital discs shifted from 16 to 29° C rapidly lose their capacity to differentiate female genital structures, while they become able to differentiate male genital structures whose inventory is more complete the earlier in larval development the temperature shift is carried out; moreover, duplicated male genital structures were observed. In the shift from 29 to 16° C, the genital disc loses its capacity to differentiate male genital structures, while it becomes able to differentiate female genital structures. The inventory of male structures is smaller, and the inventory of the female structures is more complete, the earlier in larval development the temperature is shifted. No duplicated female or male genital structures were observed in the downshift experiment. With respect to the analia, the shift from 16 to 29° C resulted in the quick formation of pure male anal plates, while in the opposite shift the formation of pure female anal plates occurred gradually. Moreover, the time course for the dorsal and ventral anal plates to show normal female phenotype was different: when the dorsal anal plates were completely normal, it was still possible to find incomplete ventral anal plates. In the pulse experiment at 29° C, the genital disc is able to differentiate both female and male genital structures, although the inventory of the latter ones was not complete. In addition, the capacity of the genital disc to differentiate male genital structures depended on the duration of the temperature pulse. The anal plates were always female, although they showed a reduction in their size, the ventral female anal plate being more affected than the dorsal one. No male anal plates were observed. The results have revealed that the genital disc follows a sequence in its capacity to differentiate female or male adult structures. We suggest that this sequence reflects the sequence of determination events occurring in the genital disc during its larval growth. In addition, results shown here provide evidence for the existence in the female genital primordium of a set of cells capable of giving rise either to female genital structures (ventral vaginal plates) or to male genital structures (hypandrium and penis apparatus). We also present evidence supporting the previous idea of two primordia for the anal plates.
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  • 61
    ISSN: 1432-041X
    Keywords: Drosophila ; Homeotic gene regulation ; Antennapedia ; Development ; β-galactosidase
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    Notes: Summary In order to study the regulation of spatial and temporal expression of the homeotic gene Antennapedia (Antp) in Drosophila melanogaster, we have constructed fusion genes which contain Antp sequences linked to the reporter gene lac Z of Escherichia coli. In one case of P-element transformation, a fusion gene construct integrated into the endogenous Antp gene close to one of the two promoters (P1). The spatial expression from the reporter gene in this transformant line, as analysed by the detection of β-galactosidase activity, was found to exactly mimic the normal expression from the P1 promoter of the Antp gene. We have used this unique transformant as a tool for studying the expression of the P1 promoter in embryonic, larval and adult development. Parallel lines transformed with the same fusion gene construct did not confer a correct P1 pattern of expression. The position in the genome was, therefore, crucial for the expression pattern of the reporter gene. Experiments aiming at the detection of autoregulatory control of Antp gene expression were designed. The results did not, however, support models of positive or negative autoregulation of P1 expression by Amp protein.
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  • 62
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    Development genes and evolution 201 (1992), S. 120-123 
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    Keywords: Integrin ; Drosophila ; In vitro ; Imaginal disc
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    Notes: Summary Drosophila imaginal disc cell lines show a characteristic pattern of aggregation in culture, which appears to be due to cell-cell rather than cell-substrate interactions. We have examined the distribution of PS integrins in wing and leg cell lines, and find that these integrin homologues are expressed preferentially in aggregates. Cell sheets, small cell clumps and chains of cells express antigen at points of cell-cell contact only.
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  • 63
    ISSN: 1432-041X
    Keywords: Drosophila ; Pattern formation ; Segment polarity genes ; gooseberry ; Cell interactions
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    Notes: Summary Segment polarity genes define the cell states that are required for proper organization of each metameric unit of the Drosophila embryo. Among these, the gooseberry locus has been shown to be composed of two closely related genes which are expressed in an overlapping single-segment periodicity. We have used specific antibodies raised against the protein product of the gooseberry proximal (gsb-p) gene to determine the spatial distribution of this antigen in wild type embryos, and to monitor the effects of segment polarity mutants on the pattern of the gsb-p protein distribution. We find that the gsb-p protein accumulates beneath each posterior axonal commissure in the progeny of neuroblasts deriving from the epidermal compartments of wingless (wg) and engrailed (en) expression. The results of this analysis support the idea that gsb-p has a specific role in the control of cell fates during neurogenesis, and indicate that en and wg provide critical positional cues to define the domain in which gsbp will be activated. Furthermore, these data suggest that, in order to be expressed in the embryonic CNS, gsb-p may preliminarily require activity of the gooseberry-distal gene in the epidermis.
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    Development genes and evolution 201 (1992), S. 88-94 
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    Keywords: Fate map ; Drosophila ; Flight muscle ; Mosaics ; Cell lineage
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    Notes: Summary A blastoderm fate map has been prepared for Drosophila, using mosaics of a temperature-sensitive mutation, shibire (shi). The mutation can cause abnormal flight muscle morphology, inducible only by a short heat pulse in early metamorphosis. Thus muscle lineage and development are unperturbed until the heat pulse in the early pupa. The developmental focus of the shi muscle phenotype maps to the ventral thorax at the expected site of thoracic mesoderm, and probably indicates the blastoderm progenitors of the adult flight muscle. The fate map provides greater detail than previously available for the dorsolongitudinal fibers (DLM) of flight muscle, showing wide separation of the fibers of flight muscle. DLM fibers a and b map close together, and far anterior to fibers e and f, which also map together. On a fate map, common developmental focus indicates a common blastoderm origin. Thus, the observed pattern for DLM fibers suggests that the blastoderm progenitors for each of these syncytial fiber pairs (a, b; e, f) include only one or two cells. It follows that there is usually a single genotype within each fiber pair (a, b; e, f), and that this genotype is directly reflected in the fiber phenotype. In a large number of cases, DLM fibers a and b differ in phenotype from other DLM fibers, in parallel with their other differences (e.g., timing of development in pupa, innervation, motor activity). The separation of fate map locations of the developmental focus for DLM fibers within mesoderm suggests that specific fibers of flight muscle may, in normal development, originate in all three thoracic mesodermal parasegments.
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    Development genes and evolution 202 (1992), S. 23-35 
    ISSN: 1432-041X
    Keywords: Ecdysteroid ; Imaginal disc ; Drosophila ; Cell line
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    Topics: Biology
    Notes: Summary We have investigated the action of the moulting hormone 20-hydroxy ecdysone (20-HOE) on our leg and wing imaginal disc cell lines. At the morphological level, cells stop dividing and there is some cell death. The remaining cells elongate and aggregate, often producing long processes which form connections between different aggregates. 20-HOE acts within the first one or two days of a passage, at an optimum concentration of 10 ng/ml, this being about 1/100 of the optimum for ecdysone. One cloned wing cell line, C9, has been found to be relatively insensitive to the action of 20-HOE. We have been able to select for resistance to 20-HOE by growing cells in gradually increasing concentrations of hormone followed by passages in hormone-free medium. This has enabled us to isolate a wing cell line C1.8R from its parent cloned line C1.8+. This shows no response to 20-HOE, and cell growth continues even at hormone concentrations as high as 150 ng/ml. We have measured chitin synthesis by the incorporation of radioactive glucosamine into a cell fraction resistant to extensive alkali hydrolysis. The residue was incubated with chitinase, which resulted in a 50% reduction in labelled product. Treatment with 10 ng/ml of 20-HOE dramatically increased chitin synthesis in line C1.8+, but had no effect in the line C1.8R, selected for resistance to hormone.
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  • 66
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    Development genes and evolution 202 (1992), S. 49-60 
    ISSN: 1432-041X
    Keywords: Drosophila ; Delta ; Enhancers ; Suppressors ; Neurogenesis
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    Topics: Biology
    Notes: Summary We have screened for dominant enhancers and suppressors of the wing phenotype associated with two Delta alleles: Dl 9P39, an amorphic allele, and Dl FE32, an antimorphic allele. The interactions of some of the modifiers with Delta are due to haplo-insufficient expression of the corresponding genes. Although not explicitly shown for the remaining cases, we assume that haploin-sufficiency is also the basis for the relationships of these genes to Delta, since no allele specific interactions were observed. The modifiers found define 22 genes with pleiotropic expression, which can be classified into two groups: genes required for wing vein pattern formation and for neurogenesis, and genes which are not required for neurogenesis. Among the genes of the first group, Hairless and Star were previously known to participate in neural development. One further modifier was found which may correspond to a new neurogenic gene. The second group of genes is larger and includes already known loci, e.g., Plexate, blistered, plexus, etc, as well as other previously unidentified genes, which function during wing morphogenesis.
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  • 67
    ISSN: 1432-041X
    Keywords: Ionic currents ; Ca2+/Mg2+ ATPase ; Molluscan eggs ; Cell cycle ; Calcium
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    Notes: Summary During the first four mitotic division cycles of Lymnaea stagnalis embryos, we have detected cell cycle-dependent changes in the pattern of transcellular ionic currents and membrane-bound Ca2+-stimulated ATPase activity. Ionic currents ranging from 0.05 to 2.50 μA/cm2 have been measured using the vibrating probe technique. Enzyme activity was detected using Ando's cytochemical method (Ando et al. 1981) which reveals Ca2+/Mg2+ ATPase localization at the ultrastructural level, and under high-stringency conditions with respect to calcium availability, it reveals Ca2+-stimulated ATPase. The ionic currents and Ca2+-stimulated ATPase localization have in common that important changes occur during the M-phase of the cell cycles. Minimal outward current at the vegetal pole coincides with metaphase/anaphase. Maximal inward current at the animal pole coincides with the onset of cytokinesis at that pole. Ca2+-stimulated ATPase is absent from one half of the embryo at metaphase/anaphase of the two- and four-cell stage, whereas it is present in all cells during the remaining part of the cell cycle. Since fluctuations of cytosolic free calcium concentrations appear to correlate with both karyokinesis and cytokinesis, we speculate that part of the cyclic pattern of Ca2+-stimulated ATPase localization and of the transcellular ionic currents reflects the elevation of cytosolic free calcium concentration during the M-phase.
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  • 68
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    Development genes and evolution 200 (1991), S. 172-176 
    ISSN: 1432-041X
    Keywords: Drosophila ; Sxl expression ; fl(2)d ; Adult life
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    Topics: Biology
    Notes: Summary In Drosophila melanogaster, the gene Sex-lethal (Sxl) controls the processes of sex determination, dosage compensation, oogenesis and sexual behaviour. The control of Sxl is by alternative splicing of its primary RNA. We have identified a gene, female-lethal-2-d (fl(2)d), which is needed for the female-specific splicing of Sxl RNA and which also has a vital function independent of Sxl. Here we analyse other aspects of the gene fl(2)d. Specifically, we have analysed the effect of the temperature-sensitive mutation fl(2)d 1 on the viability of adult flies homozygous for this mutation. We have found that the viability of the mutant females is reduced, while that of the mutant males is not affected. In addition, the capacity of the mutant females to be inseminated is considerably reduced, whilst all the mutant males are able to inseminate females. These effects on females are suppressed by Sxl M1. However, the fat body cells of fl(2)d 1 homozygous females are able to synthesize yolk proteins at the restrictive temperature. We have also carried out, in males, a clonal analysis of fl(2)d 2, a mutation lethal in both sexes. We have found that the clones are fully viable. We conclude that the gene fl(2)d seems to be necessary during the adult life of females for the processes that require Sxl + activity. Moreover, the Sxl-independent vital function of fl(2)d seems to be required in both sexes only during larval development.
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  • 69
    ISSN: 1432-041X
    Keywords: Ionic currents ; Ca2−/Mg+ ATPase ; Molluscan embryo ; Mesoderm induction ; Calcium
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    Notes: Summary InLymnaea stagnalis, mesoderm induction occurs at the 24-cell stage, when the apical tip of the macromere 3D establishes a close contact with a number of micromeres. Via its tip, the macromere 3D is supposed to receive an inductive signal from the micromeres, resulting in the determination of the mesodermal stem cell 4d at the next division. In view of the possibility that transcellular ionic currents might somehow be involved, either in the processes that bring about this particular configuration of blastomeres or in the induction process itself, we mapped the electric field around the embryo during the 24-cell stage, using a vibrating probe. We detected a reversal of the current direction as compared to the uncleaved egg, whilst the polarity of the field along the animal-vegetal axis was maintained. We also mapped the localization of Ca2+-stimulated AT-Pase, an enzyme that drives the Ca2+-efflux from the cell. We found that this enzyme is localized exclusively along the cytoplasmic face of the apical plasma membrane of macromere 3D, and that its presence is restricted to the period from 110 to 135 min after the fifth cleavage, when there is close contact between macormere 3D and the micromeres. Since the localization of the Ca2+-stimulated ATPase coincides both in time and space with the induction of the mesoderm-mother cell, we suggest that localized calcium fluxes may play a role in this induction process.
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  • 70
    ISSN: 1432-041X
    Keywords: Determination ; Germ-line ; Somatic cells ; Inhibitor gradient hypothesis ; Drosophila
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    Notes: Summary A hypothesis is presented which explains the segregation of germ cells from somatic cells, and the subsequent determination of both cell types with a single mechanism. This hypothesis is in part based on that of Meinhardt (1977) and can be summarized as follows: In the newly fertilized egg, the action of a sink in the pole plasm leads to the formation of an anterior-posterior gradient of an inhibitor. The concentration of this inhibitor in the posterior 20% of the egg is below that needed to repress synthesis of an activator. When, during the nuclear division stage, nuclei enter this posterior region, synthesis of the activator begins. As the activator is autocatalytic, this leads to the formation of a peak of activator in this region; and since the activator also catalyses the synthesis of the inhibitor, a peak of inhibitor is formed in the same place. The inhibitor then diffuses anteriorly through the periplasm, forming a posterior-anterior gradient. The presence of this inhibitor in the periplasm causes the nuclei that enter the periplasm to form blastoderm cells and to take up particular segmental states appropriate to their position, while those that remain in the yolk-containing plasm develop into vitellophages. The action of the sink in the pole plasm is postulated to result in the formation of the pole cells, and subsequently to direct some of these into forming cells of the germ-line.
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  • 71
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    Development genes and evolution 189 (1980), S. 1-15 
    ISSN: 1432-041X
    Keywords: Cell line ; Drosophila ; Ecdysone ; Ecdysterone ; Hormones
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    Topics: Biology
    Notes: Summary Cells of the line Kc, derived fromDrosophila melanogaster embryos, extend long processes when exposed to ecdysteroid hormones. We have devised a quantitative assay for this morphological response, using the subline Kc-H. The assay was used to characterize the conditions required for the response. A halfmaximal response is elicited by approximately 10−8M 20-hydroxyecdysone; the response is saturated by 10−7M 20-hydroxyecdysone, which causes detectable elongation within a few hours, and a maximal response after 2–3 days. The response occurs substantially normally in the absence of serum, during growth in suspension, and in over-crowded cultures. It is not elicited by cyclic nucleotides, vertebrate growth factors, or a variety of other non-ecdysteroid reagents. Of 60 ecdysteroid compounds tested, only those which were active in other insect test systems elicited the response, and the concentrations required were approximately proportional to the concentrations active in other in vitro systems. We conclude that the response of Kc cells to 20-hydroxyecdysone retains basic features of the ecdysteroid response of intact tissues and therefore that Kc cells are a useful model system for studying ecdysteroid action.
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  • 72
    ISSN: 1432-041X
    Keywords: Eggshell ; Chorion ; Peroxidase ; Crosslinking ; Drosophila
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    Notes: Summary TheDrosophila chorion contains an endogenous peroxidase activity which remains inactive until late stage 14 when it catalyzes the crosslinking of the chorionic proteins. Using explanted follicles developing in vitro, premature, but otherwise normal crosslinking can be induced with hydrogen peroxide and normal crosslinking can be prevented with peroxidase inhibitors. Inhibition or premature activation of the shell peroxidase allows characterization of chorionic filament specific proteins and establishes new criteria for the identification of eggshell components.
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  • 73
    ISSN: 1432-041X
    Keywords: Early neurogenesis ; Neurogenic mutants ; Drosophila
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    Notes: Summary The central nervous system (CNS) ofDrosophila develops from precursor cells called neuroblasts. Neuroblasts segregate in early embryogenesis from an apparantly undifferentiated ectoderm and move into the embryo, whereas most of the remaining ectodermal cells continue development as epidermal cell precursors. Segregation of neuroblasts occurs within a region called the neurogenic field. We are interested in understanding how the genome ofDrosophila controls the parcelling of the ectoderm into epidermal and neural territories. We describe here mutations belonging to seven complementation groups which effect an abnormal neurogenesis. The phenotypes produced by these mutations are similar. Essential features of these phenotypes are a conspicuous hypertrophy of the CNS accompanied by epidermal defects; the remaining organs and tissues of the mutants are apparently unaffected. The study of mutant phenotype development strongly suggests this phenotype to be due to misrouting into the neural pathway of development of ectodermal cells which in the wildtype would have given rise to epidermal cells, i.e. to an initial enlargement of the neurogenic region at the expense of the epidermogenic region. These observations indicate that the seven genetic loci revealed by the mutations described in this study contribute to control the neurogenic field. The present results suggest that in wildtype development neurogenic genes are supressed within all derivatives of the mesoderm and endoderm and some derivatives of the ectoderm, and conditionally expressed in the remaining ectoderm. The organisation of the neurogenic field in the wildtype is discussed.
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  • 74
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    Development genes and evolution 188 (1980), S. 153-156 
    ISSN: 1432-041X
    Keywords: Drosophila ; Embryogenesis ; mat (3) 1 mutation ; Two-dimensional gels
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    Topics: Biology
    Notes: Summary The synthesis of a protein which has been detected in blastoderm cells but not in pole cells (Gutzeit and Gehring 1979) has been studied further by means of two-dimensional gel electrophoresis. This protein could not be detected at the nuclear multiplication stage. The protein is translated from mRNA which is transcribed at the blastoderm stage since it is not synthesized in detectable amounts when embryos are injected with α-amanitin prior to the blastoderm stage. Also the protein could not be detected when RNA from freshly laid eggs was translated in vitro. Embryos from females which are homozygous for the mutationmat (3) 1 form pole cells but no blastoderm cells (Rice and Garen 1975). Thesemat (3) 1 embryos, as we will call them in this report, express the protein if aged for a period of time sufficient for completion of blastoderm cell formation in control wild-type embryos.mat (3) 1 embryos and embryos injected with α-amanitin show the same syndrome of visible developmental anomalies; however, the studied protein could only be detected inmat (3) 1 embryos but not in α-amanitin injected embryos.
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  • 75
    ISSN: 1432-041X
    Keywords: Drosophila ; Geographic strains ; Chorion proteins ; Electrophoretic variants ; Chorion gene linkage
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    Notes: Summary Drosophila melanogaster chorion proteins are characterized on one-dimensional isoelectric focusing (IF) gels. The six major chorion components previously identified on SDS gels are shown to resolve into at least 11 components in our IF system. IF screening of 102 geographic strains ofDrosophila melanogaster revealed seven cases of variation in major chorion components. Two strains, Crimea and Falsterbo, which were monomorphic for a variant B1 protein and two strains, Skafto and Lausanne, which were monomorphic for a variant C1 protein, were chosen for further study. After IF developmental analysis of F1 hybrids had indicated that the sources of the variation resided in the structural genes for these proteins, each variant was crossed to a multiply marked and inverted strain (BLT) to determine the linkage group of the variant gene. To localize genes to more specific sites multiply marked 3rd (SKERO) or X-chromosomal (CB1) (X-PLE) mapping strains were used. In both Crimea and Falsterbo the gene for the B1 protein is located near map location 26 on the 3rd chromosome. In both Lausanne and Skafto the C1 gene is located on the X chromosome. Hence, for the first time, we have demonstrated genetically the non-linkage of two chorion genes, B1 and C1.
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  • 76
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    Development genes and evolution 189 (1980), S. 147-153 
    ISSN: 1432-041X
    Keywords: Homeotic mutant ; Drosophila ; Clonal analysis ; Timing of gene action ; Determination
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    Notes: Summary Nasobemia (Ns) is a dominant homeotic mutant ofDrosophila melanogaster which converts parts or all of the antenna to mesothoracic leg.Ns has a temperature sensitive period between 48 and 60 h. The hypothesis thatNs acts during this period and is not required thereafter to maintain the homeotic transformation to leg was tested by removingNs fromNs/+ cells at different stages of development through X-ray induced somatic recombination. The expression of theNs homeotic transformation in recombinant wild type (+/+) cells increased sharply between 48 and 65 h. In clones induced after 65 h the expression of the leg transformation was equal in large and small +/+ clones. We interpret these results as supporting the hypothesis that transient action ofNs between 48 and 65 h switches antennal cells to a clonally stable leg determined state whose maintenance does not require futherNs action.
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    Development genes and evolution 201 (1992), S. 1-11 
    ISSN: 1432-041X
    Keywords: Drosophila ; Neurogenesis ; Signals ; Delta ; Notch
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    Notes: Summary The ectodermal germ layer of Drosophila melanogaster gives rise to two major cell lineages, the neural and the epidermal. Progenitor cells for each of these lineages arise from groups of cells, whose elements must decide between taking on either fate. Commitment of the progenitor cells to one of the developmental fates implies two factors. One is intrinsic to the ectodermal cells and determines a propensity to take on neural fate; this factor is probably represented by the products of the so-called proneural genes, which are differentially distributed throughout the ectoderm. The other factor in the cells' decision to adopt one of the two alternative fates is intercellular communication, which is mediated by the products of the so-called neurogenic genes. Two types of interactions, one inhibiting and the other stimulating neural development, have been inferred. We discuss here the assumed role of various neurogenic genes, in particular Notch and Delta, in these processes.
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  • 78
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    Development genes and evolution 201 (1992), S. 194-220 
    ISSN: 1432-041X
    Keywords: Drosophila ; Enhancer trap lines ; Embryogenesis
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    Topics: Biology
    Notes: Summary Embryos of 171 Drosophila lines carrying a P-lacZ insertion on the second or third chromosome were analyzed regarding their pattern of lacZ expression. All lines were selected from a larger screen of about 4000 lines (Bier et al. 1989). Tissue specificity and time of onset of lacZ expression was documented for each line. Thereby, a comprehensive list of markers for the various tissue and cell types of the Drosophila embryo could be assembled. With the help of several P-lacZ lines the development of a number of structures was studied which so far had been described only insufficiently or not at all. In particular, the embryonic origin and early development of the oenocytes, imaginal discs, histoblasts, fat body, dorsal vessel, and perineurial cells was analyzed. Several previously unknown cell types associated with the dorsal vessel, trachea, and epidermis were discovered. By combining data regarding the origin of the different mesodermally derived organs it was possible to generate in some detail a fate map of the mesoderm of the stage 11 Drosophila embryo.
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  • 79
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    Development genes and evolution 204 (1995), S. 259-270 
    ISSN: 1432-041X
    Keywords: Ig-like domains ; Cell adhesion ; Peripheral and central nervous system ; Muscles ; Drosophila
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    Notes: Abstract The Drosophila neuromusculin (nrm) gene encodes an immunoglobulin-like (Ig-like) cell adhesion molecule expressed in the precursors of the embryonic peripheral nervous system (PNS), in the midline precursors of the central nervous system (CNS), and in muscles. During the initial phases of CNS axonogenesis, nrm is expressed in cells involved in the development of commissures and longitudinal tracts. Mutations which alter expression of nrm mRNAs cause aberrant development of commissures and longitudinal axon pathways. Defects in the PNS and muscles of nrm mutants are also observed. In most nrm embryos, abnormal development can be detected in a subset of abdominal segments; however, in approximately 1 of 10 nrm embryos, the defects extend to all segments. Herein, we present evidence that nrm plays an important role in early morphogenesis, possibly by mediating or facilitating inductive cell contacts and movements.
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  • 80
    ISSN: 1432-041X
    Keywords: Drosophila ; Central nervous system ; Glia GAL4 enhancer trap ; Classification
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    Notes: Abstract To facilitate the investigation of glial development inDrosophila, we present a detailed description of theDrosophila glial cells in the ventral nerve cord. A GAL4 enhancer-trap screen for glial-specific expression was performed. Using UAS-lacZ and UAS-kinesin-lacZ as reporter constructs, we describe the distribution and morphology of the identified glial cells in the fully differentiated ventral nerve cord of first-instar larvae just after hatching. The three-dimensional structure of the glial network was reconstructed using a computer. Using the strains with consistent GAL4 expression during late embryogenesis, we traced back the development of the identified cells to provide a glial map at embryonic stage 16. We identify typically 60 (54–64) glial cells per abdominal neuromere both in embryos and early larvae. They are divided into six subtypes under three categories: surface-associated glia (16–18 subperineurial glial cells and 6–8 channel glial cells), cortex-associated glia (6–8 cell body glial cells), and neuropile-associated glia (8–10 nerve root glial cells, 14–16 interface glial cells, and 3–4 midline glial cells). The proposed glial classification system is discussed in comparison with previous insect glial classifications.
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  • 81
    ISSN: 1432-041X
    Keywords: Drosophila ; Extramacrochaetae ; Pattern formation ; Sensory bristle positioning
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    Notes: Abstract We examine the effect of mutations in theextramacrochaetae (emc) gene on the positioning of macrochaetes on the notum ofDrosophila. We show that, inemc mutants, most of the precursor cells appear earlier than in wild-type individuals, consistent with an antagonizing effect ofemc on the action of the proneural genesachaete andscute. We also show that reducingemc function affects the position of three bristles and/or of their precursors, but has no marked effect on the positioning of the other bristles.
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    Development genes and evolution 204 (1995), S. 330-335 
    ISSN: 1432-041X
    Keywords: Drosophila ; top mutation ; DER gene ; Histoblast nests ; Morphogenesis
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    Notes: Abstract TheDrosophila homolog of the vertebrate EGF receptor (DER) gene is encoded by thetorpedo (top) locus. We examined the role oftop in the development and differentiation of the integument of the adult abdomen ofDrosophila, by analysing these processes in transheterozygotes of twotop alleles. The mutation, when compared to the wild type, affected mitosis, spreading and differentiation of adult epidermal cells derived from the various histoblast and spiracular nests. Our observations indicate that the need for wild-typetop gene product becomes critical after pupation, and the requirement continues throughout the rest of adult development for the normal morphogenesis of the abdominal integument and spiracles.
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  • 83
    ISSN: 1432-041X
    Keywords: Drosophila ; Steroids ; Glucocorticoids ; Embryogenesis ; Amnioserosa
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    Notes: Abstract We have investigated the effects of the glucocorticoid, dexamethasone, and five structural analogs on Drosophila development in an effort to identify steroid ligands that may play a role in the embryogenesis of this organism. Embryos were exposed to glucocorticoids either by direct culture in supplemented medium, or by examining embryos from adult flies raised on supplemented fly food. After exposure, embryos were examined for developmental defects. At a morphological level, exposure to dexamethasone disrupts the dorsolateral folding of the amnioserosa during germ band extension. In addition, germ band retraction and dorsal closure is also disrupted. The phenocritical period of these effects is within the first 4 h of embryogenesis. This response is dosage sensitive, with embryos responding to concentrations of dexamethasone ranging from 10−6 to 10−3M. Furthermore, glucocorticoids which are closely related structural analogs of dexamethasone also disrupt germ band retraction and dorsal closure, while other tested steroids had no effect on embryonic development. At a molecular level, expression of the gene, Krüppel, is absent from the amnioserosa of dexamethasone-treated embryos. The cuticular phenocopy resulting from exposure to dexamethasone and related glucocorticoids is morphologically similar to the mutant phenotype associated with four genes required for germ band retraction, namely hindsight, serpent, tail-up and u-shaped. The results of this study represent the first association of a glucocorticoid with dose, stage and tissue specific effects on Drosophila development at both morphological and molecular levels.
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  • 84
    ISSN: 1432-041X
    Keywords: Positional information ; Polar coordinate model ; Enhancer trap ; Imaginal disc ; Drosophila
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    Notes: Abstract We have isolated three classes of “enhancertrap” lines of Drosophila in which lacZ expression patterns in the imaginal discs are consistent with the idea of a polar (radial and angular) coordinate system of positional information. In the first class (HZ76), a circular pattern was expressed transiently during the mid-third instar larval stage when the radial components of the coordinate are probably generated. The expression patterns of the second class (HZ84) were sector-shaped and circular in the leg disc, suggesting a correlation with both radial and angular coordinate values. The expression patterns found in the third class (PZ63 and PZ22) were circular and appeared to reflect radial positional values. Expression in the latter two classes always began in the presumptive dorsal region of the leg disc and gradually spread to the ventral region. These developmental profiles of expression suggested the existence of a centre that initiates patterned gene expression in the presumptive dorsal region of the leg disc. The PZ22 line showed transient expression during tarsal segmentation, suggesting its involvement in tarsal segment formation. We have cloned the PZ22 gene and partially determined its sequence. The deduced amino acid sequence contained a zinc finger motif found in DNA/RNA binding proteins. By in situ hybridization, we determined that the PZ22 gene was transcribed in the leg disc in a pattern identical to that of the lacZ expression. In addition, it was expressed transiently in the embryonic mesoderm during mesoderm segmentation. The PZ22 gene, therefore, may function both in mesodermal segmentation in the embryo and in tarsal segmentation in the imaginal disc.
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    Development genes and evolution 205 (1995), S. 160-170 
    ISSN: 1432-041X
    Keywords: Drosophila ; Evolution ; fz ; Homeodomain ; Plasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Drosophila melanogaster segmentation gene fushi tarazu (ftz) encodes a homeodomain-type transcription factor involved in the control of larval pattern formation. Loss of function mutations cause an embryonic lethal, pair-rule phenotype. The segmentation defects, but not the lethality, can be partially rescued by the ftz orthologue from Drosophila hydei. In this work, the primary structure, expression and regulation of the D. hydei ftz gene was characterized. Sequence comparisons classify ftz as a rather fast evolving gene. However, since the homeodomain of the D. hydei FTZ protein is highly similar to that of D. melanogaster, proper regulation of D. melanogaster ftz downstream genes would be expected. In D. melanogaster embryos, a D. hydei ftz transgene is expressed normally, independent of endogenous ftz gene activity, suggesting that D. hydei ftz regulatory sequences are correctly recognized by D. melanogaster transcription factors. Accordingly, lacZ fusion constructs driven by the D. hydei ftz upstream element are expressed normally in D. melanogaster embryos. Altogether, the similarities between the two ftz orthologues by far outweigh the differences. The limited success of the trans-species rescue might be, therefore, a consequence of the accumulation of too many subtle changes in gene function, exceeding the limits of developmental plasticity during fly embryogenesis.
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    Cellular and molecular life sciences 48 (1992), S. 623-629 
    ISSN: 1420-9071
    Keywords: Drosophila ; heat shock ; stress ; heat shock protein ; gene regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Major alterations in genetic activity have been observed in every organism after exposure to abnormally high temperatures. This phenomenon, called the heat shock response, was discovered in the fruit flyDrosophila. Studies with this organism led to the discovery of the heat shock proteins, whose genes were among the first eukaryotic genes to be cloned. Several of the most important aspects of the regulation of the heat shock response and of the functions of the heat shock proteins have been unraveled inDrosophila.
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    Calcified tissue international 32 (1980), S. 229-236 
    ISSN: 1432-0827
    Keywords: Bone ; Ion influxes ; Calcium ; Phosphate ; Exchange
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Quantitative measurements were made of the ion fluxes of calcium and phosphate into and from calvaria (mouse or rat) when clamped in specially designed micro-Ussing chambers. The effects of varying concentrations of calcium were examined on the influx and efflux of calcium and of its counterion, phosphate. A comparable series of experiments was performed with varying phosphate concentrations. Both ions, as their concentrations increased, depressed their own influx, increased their own efflux, and significantly increased the equilibrium concentration, E/K, supported by the calvaria. Similarly, both ions, as their concentrations increased, affected the influx or efflux of their counterion only slightly but did depress the counterion's equilibrium level, E/K, significantly. In spite of these changes it was shown that calvaria effectively buffered the medium at physiological concentrations of calcium and phosphate. The buffering capacity, however, was small, and the balance, E/K, was modified by small uptake or loss of either ion. The small size of the interacting mineral pool was confirmed by direct measurement of the rapidly exchanging fractions of both calcium or phosphate. They were only ∼1% of the total ions present. The significance of these findings is discussed.
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    Calcified tissue international 51 (1992), S. 35-41 
    ISSN: 1432-0827
    Keywords: Kidney ; Endoplasmic reticulum ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A subcellular fraction enriched in cytochrome c reductase (7.9-fold) and relatively de-enriched (0.64-fold) in Na+/K+-ATPase was prepared from canine kidney cortex by sucrose density gradient ultracentrifugation. It was shown by electron microscopy to consist primarily of a light fraction of endoplasmic reticulum (LER). LER vesicles displayed ATP-dependent 45Ca2+ uptake that was insensitive to 10 mM KCN or NaN3, and was promptly released by 20 μM A23187 or ionomycin. Inositol-1,4,5-trisphosphate (IP3) appeared to produce a time-dependent release of 45Ca2+. Vanadate inhibited 45Ca2+ uptake with a Ki≈0.3 mM, further suggesting that the activity resided in the ER rather than the plasma membrane. 45Ca2+ uptake by LER, at 5 μM total [Ca2+], displayed a strong dependence on divalent cations (Mg2+〉Co2+〉Mn2+≫Ba2+≥Cd2+≥Sr2+, present at 2 mM) as well as on monovalent cations (Na+≥K++Na+ 〉K+〉Li+〉choline+), and anions (Cl-〉acetate-≥NO3 -≥F-〉H2PO4 -≫gluconate-≥oxalate=≫SO4 =). It had a fairly narrow pH optimum (7.25–7.50). Preincubation (10 min) of LER vesicles with 12-O-tetradecanoylphorbol-13-acetate (TPA) stimulated LER Ca2+ uptake; this effect was enhanced in the presence of renal cytosol [5% (vol/vol)]. However, Ca2+ uptake was not affected by preincubation with dibutyryl cyclic AMP, calmodulin, or 1,25-(OH)2-vitamin D3, either in the absence or presence of renal cytosol. Thus, the Mg2+-ATP dependent 45Ca2+ uptake activity of this canine renal cortical LER fraction displays modulation by IP3, TPA, and pH that appears to be physiologically relevant.
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  • 89
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    Calcified tissue international 51 (1992), S. 143-150 
    ISSN: 1432-0827
    Keywords: Adsorption ; Magnesium ; Calcium ; Apatite crystals ; Enamel ; Dentin ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Magnesium (Mg) is a conspicuous constituent of hard tissues but its possible role in biomineralization is poorly understood. It is possible that Mg2+ adsorbed onto bioapatites may contribute to the modulation of crystal growth as such inhibitory activity has been reported for synthetic apatites. The present study was undertaken to determine the adsorption isotherms of Mg ions onto synthetic apatites and biominerals in tooth and bone tissues in the presence of other ions of natural occurrence. Synthetic crystals used as adsorbents were hydroxyapatite and, as a better prototype for the biomineral, Mg-containing carbonatoapatite. Human enamel and dentin materials were obtained from extracted, caries-free, permanent teeth. Porcine dentin materials at two developmental stages were obtained from erupted deciduous and unerupted permanent teeth of a 6-month-old slaughtered piglet. Porcine bone was obtained from the cortical portion of the mandible of the same animal. All biomineral samples were pulverized and then treated by plasma ashing (deproteination) at about 60°C. Each of the powdered samples was equilibrated in solutions containing various initial concentrations of Mg2+, Ca2+, and Na+ (or K+) as nitrate salts. Following equilibration, concentrations (and activities) of magnesium and calcium ions in the experimental solution were determined. The pH values of the equilibrium solutions were in the range of 6.2–6.5. Experimental data of the Mg adsorption onto hydroxyapatite were interpreted on the basis of a Langmuir-type model for binary systems assuming competition of Mg2+ and Ca2+ for the same adsorption sites on the crystal surfaces of the apatites. According to this model, the adsorbed Mg is expressed as a function of the ionic activity ratio (Mg2+)/(Ca2+) in the equilibrium solution. The model contains two parameters, the adsorption selectivity constant Ks and the maximum number of adsorption sites N (μmol/g). The numerical values of Ks were similar for all adsorbents used (synthetic and biological) and indicated the preferential adsorption of Ca2+ probably due to spacial restrictions extending to the very surface of the crystals. The initial level of Mg2+ in the surface pool was different in the various biominerals, probably reflecting the composition of fluid in which the biominerals were formed. Whereas the surface pool of Mg of human enamel was marginal, only 5% of the total Mg, significant fractions of the total Mg in human and porcine dentins (about 20–30%), and porcine bone (about 40%) existed on the crystal surfaces. There were significant differences in the total Mg and the value of the parameter N between young (unerupted) and mature (erupted) dentin minerals. It was ascertained that the occupancy of adsorption sites by Mg ions became greater with maturation of the dentin tissues. The overall results suggest that the Mg-mineral interaction in tooth and bone tissues may be a highly tissue-specific process, presumably reflecting differences in fluid composition (particularly Ca and Mg activities) responsible for biomineralization.
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  • 90
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    Calcified tissue international 56 (1995), S. 372-375 
    ISSN: 1432-0827
    Keywords: Calcitonin ; Calcium ; Renal calbindin-D28k ; Intestinal calbindin-D9k ; 1,25(OH)2D3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Infusion of calcitonin lowers circulating calcium, but in the distal tubule of the kidney, pharmacological doses of calcitonin increase the active calcium reabsorption. Calbindin-D28k plays a significant role in the calcium reabsorption in the distal convoluted tubule of the kidney. The effect of calcitonin on renal calbindin-D28k in relation to calcium metabolic changes was therefore examined. In study 1, thyroparathyroidectomy followed by autotransplantation of the parathyroid glands (TX) was compared with a sham operation in rats. TX reduced plasma calcitonin from 54±2 to 9±1 pg/ml (P〈0.001), whereas ionized calcium and parathyroid hormone were returned to the control value after an initial decrease, indicating a successful implantation of the parathyroid glands. No changes were seen in calbindin-D or plasma 1,25(OH)2D. In study 2, subcutaneous infusion of salmon calcitonin 2.5 U/kg/hour via osmotic pumps was compared with infusion of vehicle in rats. Ionized calcium was reduced from 1.37±0.01 to 1.33±0.02 mmol/liter (P〈0.05), whereas no changes were seen in renal or intestinal calbindin-D or in plasma 1,25(OH)2D. After TX, only calcitonin decreased whereas the other calcium metabolic parameters showed no change. This indicates that in rats, selective elimination of calcitonin does not influence other parameters of the calcium metabolism and that the effect of calcitonin on calcium transport in the distal tubule is not mediated via an increase in renal calbindin-D28k.
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  • 91
    ISSN: 1432-0827
    Keywords: Calcium ; Kinetics ; Stable isotope ; Glucocorticoids ; Osteopenia ; Mathematical modeling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Osteopenia resulting from pharmacologic doses of glucocorticoids is well known. Previously, there has been no satisfactory quantitative model describing the kinetics of calcium flow in subjects on chronic steroid use. A mathematical model of calcium isotope interaction with bone is described and applied to determine an estimate of kinetic parameters characterizing these changes. Calcium tracer dilution kinetics after a bolus injection of 42Ca were measured in 14 subjects with juvenile dermatomyositis, 6 on predinisone regimens and 8 on treatment regimens without prednisone. Irreversible tracer loss from plasma bone is found to be significantly reduced (P=0.043) in the glucocorticoidtreated patients compared with patients on nonsteroid regimens. Reversible flow to bone is noted to be similar in the two groups. These results suggest a direct effect of glucocorticoids on osteoblast function.
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  • 92
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    Calcified tissue international 57 (1995), S. 127-132 
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Insulin ; Glucose metabolism ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Hyperparathyroidism is associated with impaired glucose tolerance, and parathyroidectomy may improve carbohydrate homeostasis. It has been suggested that parathyroid hormone (PTH) suppresses insulin secretion but it is unclear whether it also interferes with the peripheral action of insulin. To evaluate in vivo effects of PTH on insulinmediated glucose utilization, 15 male Sprague Dawley rats were continuously infused with rat PTH (1–34) using an Alzet miniosmotic pump at a rate of 0.03 nm/hour. Controls were infused with the vehicle alone. Following 5 days of PTH infusion, plasma calcium (Ca) levels were higher in the PTH-infused rats (12.3±0.2 versus 9.9±0.1 mg/dl, P〈0.01). On the 5th day, glucose (700 mg/kg) and insulin (0.175 U/kg) were given as a bolus infusion through the left femoral vein, blood samples were obtained from the right femoral vein, and plasma glucose and insulin were measured at basal (0 minutes) and at 2, 5, 10, and 20 minutes postinfusion. Basal, nonfasting glucose levels were higher (166±4 versus 155±4 mg/dL, P〈0.04) in the PTH-infused rats but their insulin levels were similar to those of controls (6.5±0.6 versus 5.6 ±0.5 ng/ml). Postinfusions and maximal (2 minutes) glucose and insulin levels were similar in both groups. However, although insulin levels were similar in both groups at all measured time points, glucose levels at 20 minutes were higher in the PTH-treated rats (205±13 versus 173±9; P〈0.03). Also, calculated glucose disappearance rates (Kg) were decreased in the PTH-infused rats (4.05±0.3 versus 4.63±0.8; P=0.054), suggesting an impaired peripheral effect of insulin on glucose utilization. To gain insight into the potential contribution of the hypercalcemia or the PTH to these abnormalities, correlation evaluations were performed. Only in PTH-infused rats did plasma Ca correlate with plasma glucose at 0 and 20 minutes (r=0.6, P=0.02; r=0.7, P=0.01) and with the area under the glucose curve (r=0.6, P=0.03) during the glucose-insulin infusion. Also only in PTH-infused rats did PTH correlate with 0 (P=0.07) and 20-minute (P=0.02) plasma glucose levels. There was no correlation between either Ca or PTH and basal insulin levels or the area under the insulin curve in either group. Consequently, we suggest that in the rat, PTH infusion associated with hypercalcemia impairs insulin effect on glucose utilization in vivo and this defect may be induced by the Ca, PTH, or both.
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  • 93
    ISSN: 1432-0827
    Keywords: Bone cells ; Cyclic AMP ; Calcium ; Ascites fluid resorptive protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of a bone resorptive protein isolated from human cancer ascites fluid on bone cell calcium and cyclic AMP were studied with fetal rat cells. The osteoclast-activating factor increased bone cell calcium uptake at 37°C and 4°C with no direct effects on calcium efflux. Concentrations of the resorptive factor that increased in vitro bone resorption and cell calcium uptake had no effect on cyclic AMP. The effects of the protein on calcium uptake were not specific for bone cells, and large increases were also observed in isolated fetal rat skin cells. These studies suggest that increases in the permeability of the cell membrane to calcium are involved in the mechanism of action of the ascites fluid resorptive protein.
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  • 94
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Dissolution ; Pyrophosphate, Diphosphonates ; Calcium ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Pyrophosphate and diphosphonate ions have been said to diminish the dissolution of hydroxyapatite crystals, because they lower the equilibrium concentrations of calcium and phosphate ions in the bulk solution around hydroxyapatite crystals in a closed system. However, in a closed system these effects are not necessarily due to an effect on dissolution alone. In this paper we have used a continuous flow system to study the effects of pyrophosphate and two diphosphonates, ethane-1-hydroxy-1,1-diphosphonate and dichloromethane diphosphonate, on the dissolution of hydroxyapatite. All three compounds decreased markedly the rate of dissolution of hydroxyapatite as well as the exchangeable pools of calcium and phosphate ions around the cystals.
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  • 95
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    Calcified tissue international 31 (1980), S. 231-238 
    ISSN: 1432-0827
    Keywords: Magnesium ; Bone ; Calcium ; Parathyroid gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Calcium homeostasis and bone pathology were studied in weanling rats fed a low (70 ppm) magnesium diet for 2–21 days. The rats developed significant, progressive hypercalcemia after 6 days on the diet. The increase in blood calcium was accompanied by progressive hypoactivity of the parathyroid gland (PTG), as determined by histologic and morphometric analyses. Thus hyperactivity of the PTG could not have been responsible for the hypercalcemia observed. Histologic examination of femora and humeri from magnesium-deficient rats showed progressive subperiosteal hyperplasia, consisting of undifferentiated osteoprogenitor cells and fibrous tissue, after 7 days of deficiency. The presence of unmineralized osteoid tissue in the metaphyses indicated that mineralization was not proceeding normally. The alterations in differentiation of osteoprogenitor cells, together with the failure of mineralization, resulted in significantly lower rates of bone formation (as measured by fluorochrome labeling) in the magnesium-deficient rats. Basophilic cementing lines and inactive osteocytes in the cortices of bones from magnesium-deficient rats indicated that bone resorption was also severely reduced in magnesium deficiency. We postulate that bone magnesium depletion (66% by day 21) has a direct negative effect on osteoblastic and osteocytic activity, and may explain, in part, the decreased responsiveness of bone to parathyroid hormone (PTH) that has been observed in magnesium-deficient animals.
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  • 96
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    Calcified tissue international 32 (1980), S. 45-53 
    ISSN: 1432-0827
    Keywords: Dentin ; Periodicity ; Allometry ; Calcium ; Sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have described differences in the aspects of biological rhythms for calcium and sulfur deposition on the labial and lingual sides of the growing rabbit incisor, where growth occurs along a spiral axis. The calcium oscillations appear to be smoother on the labial side than on the lingual side. The lingual side is characterized by high-frequency rhythms with high amplitudes which possess the greatest percent of the power (Fourier analysis). These observations also reflect a difference in behavior of the mean Ca concentration across the labial and lingual sides. Sulfur rhythms on the labial side have higher amplitudes than those on the lingual side, but systematic differences in distribution of power between high and low frequencies is not as pronounced as in the case of Ca. The differences in Ca rhythms reflect differences in the growth rates of incisors on either side of the spiral axis. The labial side grows slightly faster than the lingual side, and its odontoblasts secrete Ca along the spiral axis and toward the pulp cavity at the same time. Thus the resultant direction of growth is more nearly opposite the extension of the occlusal end on the labial side, and Ca is consequently deposited over a wider area relative to that on the lingual surfaces. On the lingual side, Ca is deposited within a more limited area, and growth must therefore be continuous at high frequencies. The distribution of Ca on both sides of the tooth reflects these differences in growth rate and periodicity in two ways. First, given a unit area of tooth, the calcium concentration on the labial side is less than that of the lingual side. Second, whereas the calcium concentration on the labial side declines rapidly from the enamel-dentin junction to the pulp cavity, it is uniformly high across the lingual side because its growth is more continuous at high frequencies.
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  • 97
    ISSN: 1432-0827
    Keywords: 1α-Hydroxy vitamin D3 ; 1,25-Dihydroxyvitamin D3 ; Calcium ; Transport ; Intestine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The timed sequence of events following the oral administration of 1α-hydroxy vitamin D3 (1αOHD3) to rachitic chicks was compared to that following a comparable dose of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3). RNA polymerase activity was maximally increased 20% by 1αOHD3 within 1 to 2 h and returned to control values after 8 h. Alkaline phosphatase activity was stimulated by 4 h and was maximal (3- to 5-fold increase) at 24 h. Calcium binding protein (CaBP) was detected initially within epithelial cells at the proximal end of the villus (just above the crypt) 6 to 8 h after 1αOHD3 administration, in epithelial cells lining the proximal half of the villus by 24 h, and in epithelial cells along nearly the entire villus by 48 h. At no time did goblet cells contain CaBP. Serum calcium concentrations were significantly elevated in 2 h and maximal by 12 h (an increase of 3.6 mg/dl). Calcium accumulation by the intestinal mucosa in vitro was increased by 6 to 8 h and maximal (60% increase over controls) at 24 h. Phosphate accumulation by the intestinal mucosa in vitro was increased by 6 h and maximal (105% increase over controls) between 8 and 24 h. 1,25(OH)2D3 increased CaBP and calcium accumulation by 4 h, 2 h sooner than did 1αOHD3. 1,25(OH)2D3 decreased serum calcium levels and increased serum phosphate levels at 2 h unlike 1αOHD3. No difference in the effects of these compounds on alkaline phosphatase activity, RNA polymerase activity, and phosphate accumulation could be demonstrated. These results are consistent with the possibility that 1αOHD3 may not require conversion to 1,25(OH)2D3 for all of its biological effects.
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  • 98
    ISSN: 1432-0827
    Keywords: Perifusion ; Parathyroid hormone ; In vitro ; Calcium ; Beta regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary An in vitro perifusion system was used to study parathyroid hormone (PTH) secretion in response to calcium (Ca) and beta-adrenergic agents. Perifused parathyroid tissue responded to changes in Ca within the physiologic range during experiments up to 5 h. There was rapid secretory stimulation after exposure to low Ca, with the maximum response being observed at 20 min. Normal bovine glands showed a Ca-independent nonsuppressible component of PTH release at concentrations of Ca above physiologic. 1-isoproterenol produced rapid stimulation of PTH release, the response being blocked by a beta antagonist. The maximum secretory response to either low Ca (0.5 mM) or 1-isoproterenol (10−5 M) was enhanced when the two stimuli were applied simultaneously. The response to isoproterenol was blocked by raising Ca to 2.5 mM. Although d,l-propranolol (10−4 M) caused mild suppression of PTH release at a Ca of 1.25 mM, it did not cause additional suppression at 2.5 mM Ca nor did it decrease the response to 0.5 mM Ca stimulation. The secretory response of the gland to low Ca was sustained at a level more than double the baseline rate. The response to isoproterenol was more transient, with a return to or toward baseline secretion within 60 min. These results suggest that beta agonists and low Ca have separate but related mechanisms for stimulating PTH release and may affect different pools of hormone. The perifusion system described is a relatively simple technique for assessing the kinetics and interactions of various stimulators of PTH secretion.
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  • 99
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    Calcified tissue international 32 (1980), S. 29-44 
    ISSN: 1432-0827
    Keywords: Rabbit ; Dentin ; Calcium ; Sulfur ; Periodicity ; Circadian ; Ultradian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have identified a variety of biological rhythms involved in the apposition and mineralization of dentin in the rabbit incisor. Animals were injected during the day or night with lead acetate at 2-week intervals—to provide biological time markers in forming dentin—and transverse undecalcified sections of the lower incisors were prepared for electron microprobe analysis. The positions of the lead markers were identified, and the continuous distribution of calcium and sulfur was measured at 1 µm intervals between the markers. In thin sections stained with hematoxylin after decalcification, the widths of a series of structural increments (bands) were measured with an ocular micrometer. Fourier analysis of the data revealed spectra of structural and compositional rhythms with a range of periodicities which extended from a matter of hours [ultradian (〈24 h)] to days [infradian (〉24 h) and circadian (approximately 24 h)]. The structural and compositional rhythms appeared to be independent to the extent that they did not necessarily have the same periods, or amplitudes. Nor were there simple phase relationships between all of the rhythms. At some times, Ca and S fluctuations are inversely proportional (180° out of phase), but in other cases they are directly proportional or out of phase by varying degrees other than 180°. The analyses thus suggest that calcium and sulfur deposition (representing mineral and glycosaminoglycan deposition, respectively) are not simply inversely proportional, and that the hematoxylin-stained structural increments did not solely reflect differences in the distribution of the mineral components in dentin.
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  • 100
    ISSN: 1432-0827
    Keywords: Menopause ; Estrogens ; Bone ; Osteoporosis ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Biochemical parameters reflecting bone resorption [urinary calcium/creatinine (Ca/Cr) and hydroxyproline/ creatinine (OH/Cr)] were related to serum estrogens [estrone (E1) and estradiol (E2)] in 262 healthy women including 158 patients receiving estrogen replacement therapy (ERT) for at least 6 months, 49 eugonadal women, and 55 untreated postmenopausal women. A significant (P〈0.001) correlation exists between serum E2 and Ca/Cr: Ca/Cr (mg/dl)=-0.00044 E2 (pg/ml)+0.129 (n=262; r=-0.37), serum E2 and OH/Cr: (OH/Cr (mg/g)=-0.049 E2 (pg/ml)+18.76 (n=262; r=-0.36), serum E1 and Ca/Cr: Ca/Cr (mg/dl)=-0.0003 E1 (pg/ml)+0.127 (n=261; r=-0.28) but not between serum E1 and OH/Cr. Women with circulating levels of E2 between 60 and 90 pg/ml have a significant (P〈 0.01) reduction of Ca/Cr and OH/Cr when compared with those with lower levels of E2. Higher values of E2 do not provide additional benefit. We conclude that in postmenopausal women receiving an estrogen replacement therapy (ERT), a significant reduction of bone resorption is achieved when circulating levels of estradiol reach a value (60 pg/ml) corresponding to the one measured, in eugonadal women, during the last days of the early follicular phase of the menstrual cycle. We suggest that oral or percutaneous ERT should induce a minimal value of 60 pg/ml to prevent postmenopausal bone loss.
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