Inheritance patterns of new genetic markers and occurrence of spontaneous mosaicism in the monogenic blowfly Chrysomya rufifacies (Diptera: Calliphoridae)

 Four new genetic markers for Chrysomya rufifacies, a fly with maternal sex determination, were characterized. The markers include one body colour mutant, black body (bl), and three eye colour mutants, brown eye (br), apricot eye (ap), and red eye (w ^r ). Two of the latter, br and w ^r , turn out to be sex linked, the others behave as autosomal genes belonging to different linkage groups. w ^r is a hypomorphic and w an apomorphic mutation of the white gene, w/w is epistatic to br/br and to ap/ap. A preliminary genetic linkage map with the sex realizer F′/f  and the loci br and w residing in homomorphic sex chromosomes is established. Evidence is presented that crossing over is absent in the male sex. The possible causes of the spontaneous appearance of mosaics for eye colour observed among individuals heterozygous for recessive genes are discussed. Received: 18 March 1996/Accepted: 9 August 1996     

Genetic instability in Drosophila melanogaster

Summary An unstable long tandem duplication which includes the white locus twice, marked with w ^sp in the left and w ^17G in the right locus, when kept in males has been found to produce red-eyed sons which have lost the long duplication and with it the w ^sp and w ^17G mutants. Such exceptions were produced also when w ^17G had been exchanged for w ^a.Stocks originating from these exceptions are unstable, producing: 1) zeste males, also unstable, 2) w ^- deletions, stable, 3) transpositions of the white locus to sites in other chromosomes.The instability is interpreted as the effect of an IS element, within or adjacent to the white locus, which is supposed to retain a duplication of the proximal zeste interacting part of this locus. According to the orientation of the IS element the duplicated part can be active or inactive, giving a zeste or red eye phenotype.The frequency of exceptional offspring after X-ray treatment of the red and zeste unstable stocks have been compared to stable stocks with corresponding genotypes.     

Growth rates of North Sea macroalgae in relation to temperature,irradiance and photoperiod

Three eulittoral algae(Ulva lactuca, Porphyra umbilicalis, Chondrus crispus) and one sublittoral alga(Laminaria saccharina) from Helgoland (North Sea) were cultivated in a flow-through system at different temperatures, irradiances and daylengths. In regard to temperature there was a broad optimum at 10–15° C, except inP. umbilicalis, which grew fastest at 10 °C. A growth peak at this temperature was also found in four of 17 other North Sea macroalgae, for which the growth/temperature response was studied, whereas 13 of these species exhibited a growth optimum at 15 °C, or a broad optimum at 10–15 °C. Growth was light-saturated inU. lactuca, L. saccharina andC. crispus at photon flux densities above 70 µE m^–2s^–1, but inP. umbilicalis above 30 µE m^–2s^–1. Growth rate did not decrease notably in the eulittoral species after one week in relatively strong light (250 µE m^–2s^–1), but by about 50 % in the case of the sublittoralL. saccharina, as compared with growth under weak light conditions (30 µE m^–2s^–1). In contrast, chlorophyll content decreased in the sublittoral as well as in the eulittoral species, and the greatest change in pigment content occurred in the range 30–70 µE m^–2s^–1. Growth rate increased continuously up to photoperiods of 24 h light per day inL. saccharina andC. crispus, whereas daylength saturation occurred at photoperiods of more than 16 h light per day inU. lactuca andP. umbilicalis.     

Cloning by functional complementation, and inactivation, of theSchizosaccharomyces pombe homologue of theSaccharomyces cerevisiae geneABC1

TheSaccharomyces cerevisiae geneABC1 is required for the correct functioning of thebc ₁ complex of the mitochondrial respiratory chain. By functional complementation of aS. cerevisiae abc1 ^– mutant, we have cloned aSchizosaccharomyces pombe cDNA, whose predicted product is 50% identical to the Abc1 protein. Significant homology is also observed with bacterial, nematode, and even human amino acid sequences of unknown function, suggesting that the Abc1 protein is conserved through evolution. The cloned cDNA corresponds to a singleS. pombe geneabc1Sp, located on chromosome II, expression of which is not regulated by the carbon source. Inactivation of theabc1Sp gene by homologous gene replacement causes a respiratory deficiency which is efficiently rescued by the expression of theS. cerevisiae ABC1 gene. The inactivated strain shows a drastic decrease in thebc ₁ complex activity, a decrease in cytochromeaa3 and a slow growth phenotype. To our knowledge, this is the first example of the inactivation of a respiratory gene inS. pombe. Our results highlight the fact thatS. pombe growth is highly dependent upon respiration, and thatS. pombe could represent a valuable model for studying nucleo-mitochondrial interactions in higher eukaryotes.     

Third chromosome suppressor of position-effect variegation loci in Drosophila melanogaster

Summary As a result of a genetic analysis of 63 third chromosome suppressor mutations of position-effect variegation 12 different loci showing dominant suppression have been identified and their map positions determined. A compilcation of the genetic data available for each suppressor locus is given. The strong suppressor effects of the mutations have been quantified by measurements of white variegation inw ^m4h /w ^m4h ,w ^m4h /Y andw ^m4h /O flies. Mutant alleles of three loci were found in these studies to dominate over the strong enhancer effect of complete loss of the Y chromosome. Most of the identified loci suppressing position-effect variegation represent essential genetic funtions; only three loci represent nonessential functions. Mutations of two loci display recessive butyrate sensitivity and lethal interaction with the heterochromatic Y chromosome suggesting that these genes affect chromosomal condensation. Studies with deficiencies and triploids revealed that most of the loci represent haplo-abnormal suppressor functions. The use of the isolated mutant material for genetic, developmental and molecular studies of processes connected with gene inactivation in position-effect variegation is discussed.Dedicated to Prof. H.J. Becker on the occasion of his 6th birthday     

Die Mutabilit?t der Plastiden vonAntirrhinum Majus L.Sippe 50

Summary Experiments to raise the frequency of plastid-mutations inAntirrhinum majus have been ineffective when proplastids were X-rayed in egg-cells or were treated in meristems of growing plants by infiltration of three different chemicals.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Some observations on variegation inDrosophila

Attempts to modify experimentally the variegated phenotypes of the mutantsz inDrosophila melanogaster andw ^m2 inD. hydei, were largely unsuccessful. Transplanted eyes ofz were found to be more intensely pigmented, but this effect was not influenced by treatment of the imaginal disks or by the host's genotype. Inw ^m2, increased pigmentation was observed after treatment with 5-bromo-uracil.Thew ^m2 phenotype is strongly modified by supernumerary Y chromosomes. One Y shifts the eye colour from yellow to brown, two Y's, to dark red. In the Malpighian tubules, two Y's have a similarly strong effect, but one Y a slight effect only. Malpighian tubules ofw ^m2 larvae were used for a quantitative analysis of mottling. An average clonal cluster size of 1.1 was found. This indicates that the state of pigmentation is determined around the last cell division in the embryo.     

A comparative study on the intrinsic rates of increase ofCyrtobagous singularis andC. salviniae on the water weedSalvinia molesta

The intrinsic rates of increase (r_m) ofCyrtobagous salviniae Calder & Sands from Brazil andC. singularis Hustache from Trinidad W.I., were determined in the laboratory at 23°C, 27°C and 31°C on nitrogen-rich plants of the aquatic weed,Salvinia molesta Mitchell.Variation in oviposition and immature survivorship accounted for most of the differences between species in r_m values (exponential growth of a stable-age population in a non-limiting environment). Values for r_m were higher forC. salviniae (0.210, 0.366, 0.404) than forC. singularis (0.148, 0.140, 0.064) at the three temperatures respectively. At all temperatures,C. salviniae laid seven times more eggs thanC. singularis while at 31°C oviposition was reduced for both species by 45%, and was accompanied by a reduction in egg hatch. Oviposition byC. salviniae was almost continuous (92% of weeks with some eggs laid) whereas oviposition byC. singularis was intermittent (50% of weeks) with intervals averaging 3 weeks without oviposition. Nitrogen concentration inS. molesta affected reproduction byC. singularis more thanC. salviniae, an increase of 0.1% (dry wt) increasing weekly oviposition by 7.0% and 3.6% respectively.The differences in r_m for the two weevil species are discussed in relationship to their potential as biological control agents.

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Taux intrinsèques d'accroissement deCyrtobagous singularies Hustache andC. salviniae Calder & Sands, utilsés dans la lutte biologique contreSalvinia molesta Mitchell

Résumé Les taux intrinsèques d'accroissement (r_m) deC. salviniae du Bresil et deC. singularis de Trinidad, ont été établis au laboratoire à 23°C; 27°C; 31°C, sur des plants deS. molesta riches en azote.Les différences entre les r_m des deux espèces provenaient pour l'essentiel de la ponte et de la mortalité préimaginale. Aux 3 températures, les valeurs de r_m deC. salviniae (0.210; 0.366; 0.404) étaient supérieures à celles deC. singularis (0.148; 0.140; 0.064). A toutes les températuresC. salviniae a pondu 7 fois plus d'oeufs queC. salviniae; à 31°C, la ponte a été réduite de 45% pour les 2 espèces et été accompagnée d'une diminution des taux d'éclosion. La ponte deC. salvinae était presque continue (92% des semaines avec des oeufs), tandis que celle deC. singularis était intermittent (50% des semaines avec pontes), les interruptions étant en moyenne de 2 semaines. La teneur deS. molesta en azote a affecté la reproduction deC. singularis plus que celle deC. salviniae; un accroissement de 0.1% en poids sec, augmentant les pontes hebdomadaires respectivement de 7% et de 3.6%.Les différences de valeur de r_m des 2 espèces sont examinées pour évaluer leurs potentialités comme éléments de la lutte biologique.

     

Higher environmental temperature-induced change in synaptosomal acetylcholinesterase activity of brain regions

Expcsure of adult male albino rats to higher environmental temperature (HET) at 35° for 2–12 hr or at 45° for 1–2 hr increases hypothalamic synaptosomal acetylcholinesterase (AChE) activity. Synaptosomal AChE activity in cerebral cortex of rats exposed to 35° for 12 hr and in cerebral cortex and pons-medulla of rats exposed to 45° for 1–2 hr are also activated. AChE activity of synaptosomes prepared from normal rat brain regions incubated in-vitro at 39° or 41° for 0.5 hr increases significantly in cerebral cortex and hypothalamus. The activation of AChE in ponsmedulla is also observed when this brain region is incubated at 41° for 0.5 hr. Increase of (a) the duration of incubation at 41° and (b) the incubation temperature to 43° under in-vitro condition decreases the synaptosomal AChE activity. Lioneweaver-Burk plots indicate that (a) in-vivo and invitro HET-induced increases of brain regional synaptosomal AChE activity are coupled with an increase ofV _max without any change inK _m (b) very high temperature (43° under in-vitro condition) causes a decrease inV _max with an increase inK _m of AChE activity irrespective of brain regions. Arrhenius plots show that there is a decrease in transition temperature in hypothalamus of rats exposed to either 35° or 45°; whereas such a decrease in transition temperature of the pons-medulla and cerebral cortex regions are observed only after exposure to 45°. These results suggests that heat exposure increases the lipid fluidity of synaptosomal membrane depending on the brain region which may expose the catalytic site of the enzyme (AChE) and hence activate the synaptosomal membrane bound AChE activity in brain regions. Further the in-vitro higher temperature (43°C)-induced inhibition of synaptosomal AChE activity irrespective of brain regions may be the cause iof partial proteolysis/disaggregation of AChE oligomers and/or solubilization of this membrane-bound enzyme.To whom to address reprint requests:     

Biology and temperature relationships of Chrysopa sp., Micromus tasmaniae and Nabis capsiformis

Immature Chrysopa sp. and Nabis capsiformis required 335 and 325 d°, respectively, for development from egg to adult, while larvae of Micromus tasmaniae were able to complete development at 5°. Mean adult female longevity and oviposition rate at 23° were 52 d (max. 83 d) and 18.1 eggs/d, and 30 d (max. 43 d) and 10.4 eggs/d for C. sp. and N. capsiformis respectively, and oviposition rate of M. tasmaniae averaged 19.1 eggs/d during 5 weeks. Reduced longevity and increased oviposition rate at higher temperatures were accounted for by basing adult biology on physiological time above the immature developmental thresholds. Intrinsic rates of increase were thus calculated as 9.820, 6.868, and 8.366 eggs/10³ d° above thresholds of 10.5°, -2.9°, and 11.3° for C. sp., M. tasmaniae, and N. capsiformis, respectively.

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Résumé L'examen a porté sur l'influence de différentes températures constantes sur le développement et la biologie imaginale de trois espèces prédatrices (Chrysopa sp., peut-être C. signata, Micromus tasmaniae et Nabis capsiformis) récoltées dans des champs de coton du sud-est du Queensland en Australie. C. sp. et N. capsiformis ont besoin respectivement de 335° au dessus d'un seuil de 10.5° et de 325° au dessus d'un seuil de 11.3°, pour se développer de l'oeuf à l'adulte. Les larves de M. tasmaniae pouvant effectuer la totalité de leur dévelopment a 5°.-A 23° les longévités des femelles adultes et les taux de ponte de C. sp. et N. capsiformis sout en moyenne de 52 j. (maximum 83) et 30 j. (maximum 43) d'une part et 18.1 et 10.4 ufs par jour d'autre part. Le taux de ponte de M. tasmaniae est de 19,1 ufs par jour pendant 5 semaines à 23°. La longévité réduite et le taux de ponte accru aux températures supérieures sont interprétés en basant la biologie imaginale sur le temps physiologique au dessus des seuils de développement.Les taux d'accroissement intrinsèque (r_m) sont plus élevés aux températures élevées, principalement à la suite du taux de développement accru. M. tasmaniae possède le r_m le plus élevé à toutes les températures par suite d'un développement rapide et de seuils thermiques bas, d'une brève période précédant la ponte et d'une date de ponte maximum précoce. Le r_m de C. sp. est plus élevé que celui de N. capsiformis à la suite de son taux de ponte plus élevé.Les valeurs de r_m fixées à partir du temps physiologique sont respectivement: 9,820, 6.868 et 8,366 ufs femelles/10³ d° au dessus des seuils de 10,5°, -2,9° et 11,3° pour C. sp., M. tasmaniae et N. capsiformis.

     

Cylindrospermopsin production and release by the potentially invasive cyanobacterium Aphanizomenon ovalisporum under temperature and light gradients

The growth rates, production and release of the potent cytotoxin cylindrospermopsin (CYN) were studied in batch and semi-continuous cultures of Aphanizomenon ovalisporum (Cyanobacteria; Nostocaceae) strains UAM 289 and UAM 290 from Spain, over a gradient of temperatures (10–40 °C) and irradiances (15–340 μE m⁻² s⁻¹). This species grew in temperatures ranging from 15 °C to 35 °C as well as under all irradiances assayed. The growth rates ranged from 0.08 d⁻¹ to 0.35 d⁻¹, and the maximum growth was recorded above 30 °C and at 60 μE m⁻² s⁻¹. CYN was produced under all conditions where net growth occurred. Total CYN reached up to 6.4 μg mg⁻¹ dry weight, 2.4 μg mm⁻³ biovolume, 190.6 fg cell⁻¹ and 0.5 μg μg⁻¹ chlorophyll a. Although CYN concentrations varied only 1.9-fold within the 15–30 °C range, a drastic 25-fold decrease was observed at 35 °C. The irradiance induced up to 4-fold variations, with maximum total CYN measured at 60 μE m⁻² s⁻¹. An elevated extracellular CYN share ranging from 20% to 35% was observed during the exponential growth phase in most experiments, with extreme temperatures (15 and 35 °C) being related to the highest release (63% and 58%, respectively) and without remarkable influence of irradiance. Growth did not have a direct influence on either CYN production or release throughout the entire range of experimental conditions. Our study demonstrates a strong and stable production and release of CYN by A. ovalisporum along field-realistic gradients of temperature and light, thus becoming a predictive tool useful for the management of water bodies potentially affected by this ecologically plastic cyanobacterium.     

n-carbamoyl-d-p-hydroxyphenylglycine production using immobilized d-hydantoinase from recombinant E. coli

An immobilized d-hydantoinase was characterized and employed to produce n-carbamoyl-d-p-hydroxyphenylglycine (CpHPG) in a repeated batch process. The V_max and K_m of the immobilized d-hydantoinase at 50°C were 6.28 mm min⁻¹ g⁻¹ biocatalyst and 71.6 mm, respectively. The product CpHPG did not inhibit the activity of d-hydantoinase. Optimal reaction temperature was 60°C. A decrease in activity of immobilized d-hydantoinase due to thermal inactivation could be described as first-order decay; the deactivation energy was 23.97Kcal mol⁻¹. Under process conditions (50°C, 10% w/v substrate, and pH 8.5), the half-life of the immobilized d-hydantoinase was eight batches. The attrition of immobilized d-hydantoinase particles with a large amount of insoluble substrate particles during stirring resulted in fine biocatalyst particles. In addition to the thermal inactivation, the loss of fine biocatalyst particles during the recovery step contributed to the low operational stability.     

Regulation of the basolateral potassium conductance of theNecturus proximal tubule

Summary Two methods, the measurement of the response of the basolateral membrane potential (V _bl) of proximal tubule cells ofNecturus to step changes in basolateral K⁺ concentration, and cellular cable analysis, were used to assess the changes in basolateral potassium conductance (G _K) caused by a variety of maneuvers. The effects of some of these maneuvers on intracellular K⁺ activity (a _K ⁱ ) were also evaluated using double-barreled ion-selective electrodes. Perfusion with 0mm K⁺ basolateral solution for 15 min followed by 45 min of 1mm K⁺ solution resulted in a fall in basolateral potassium (apparent) transference number (t _K),V _bl anda _K ⁱ . Results of cable analysis showed that total basolateral resistance,R _b , rose. The electrophysiological effects of additional manipulations, known to inhibit net sodium reabsorption across the proximal tubular epithelium ofNecturus, were also investigated. Ouabain caused a fall int _K accompanied by large decreases ina _K ⁱ andV _bl. Lowering luminal sodium caused a fall int _K and a small reduction inV _bl. Selective reduction of peritubular sodium, a maneuver that has been shown to block sodium transport from lumen to peritubular fluid, also resulted in a significant decrease int _K. These results suggest thatG _K varies directly with rate of transport of the sodium pump, irrespective of the mechanism of change in pump turnover.Part of this material has been presented at the 10th International Conference on Biological Membranes (Cohen & Giebisch, 1984).     

Effect of Temperature and Illumination on Growth and Reproduction of the Green Alga Ulva fenestrata

The combined effect of temperature (5, 10, 15, and 20°C) and illumination (40 and 60 mE/(m² s)) on growth and reproduction of the green marine alga Ulva fenestrata P. et R. from the sublittoral zone of Amursky Bay, Sea of Japan, was studied in the laboratory environment in the months April–July, 2000. It was demonstrated that the temperature of 5°C and illumination of 40 mE/(m² s) are the most favorable for maintaining the vegetative mass of the algae. A water temperature of 10°C and illumination of 40 mE/(m² s) are the optimum conditions for vegetative growth of U. fenestrata thalli. A temperature decrease and increase by 5°C reduces the growth rate on average by 30%. Sporo- and gametogenesis in U. fenestrata are the most regular (every 10 days) and occupy the greatest disk area at a water temperature of 15°C and illumination of 40 mE/(m² s). Vegetative growth of thalli is sharply inhibited at the stage of cell preparation to gametogenesis a day before the beginning of gamete formation.     

The production of cyclopiazonic acid by Penicillium commune and cyclopiazonic acid and aflatoxins by Aspergillus flavus as affected by water activity and temperature on maize grains

The combined effects of water activity (a_w) and temperature on mycotoxin production by Penicilium commune (cyclopiazonic acid — CPA) and Aspergillus flavus (CPA and aflatoxins — AF) were studied on maize over a 14-day period using a statistical experimental design. Analysis of variance showed a highly significant interaction (P 0.001) between these factors and mycotoxin production. The minimum a_w/temperature for CPA production (2264 ng g^–1 P. commune, 709 ng g^–1 A. flavus) was 0.90 a_w/30 °C while greatest production (7678 ng g^–1 P. commune, 1876 ng g^–1 A. flavus) was produced at 0.98 a_w/20 °C. Least AF (411 ng g^–1) was produced at 0.90 a_w/20 °C and most (3096 ng g^–1) at 0.98 a_w/30 °C.     

Different arachidonate and palmitate binding capacities of the human red cell membrane

Human red cell membrane bindings of arachidonate and palmitate at pH 7.3 are investigated at temperatures between 0 and 38°C by equilibrating ghosts with the long-chain fatty acids bound to bovine serum albumin in molar ratios (v) within the physiological range (<1.7). Linearized relations of ghost uptakes and fatty acid monomer concentrations in buffer provide estimates of the binding capacities and corresponding equilibrium dissociation constants (K _dm ). The temperature-independent arachidonate binding capacity, 5.5 ± 0.5 nmol g^–1 packed ghosts, is approximately fivefold smaller than that of palmitate, 26.6 ± 2.0 nmol g^–1. While K _dm of arachidonate binding 5.1 ± 0.5 nm is temperature independent, K _dm of palmitate increases with temperature from 3.7 nm at 0°C to 12.7 nm at 38°C.The large difference in binding capacities suggests the presence of at least two different fatty acid binding domains in human red cell membranes.     

Thermal acclimation of aerobic metabolism and O2-Hb binding in the snake,Vipera berus

Summary Snakes,Vipera berus, were acclimated to 5 and 25 °C for 3 months preceding measurements of O₂ uptake and blood respiratory properties. O₂ uptake measured at the lower acclimation temperature (5 °C) shows lower values for the cold-acclimated snakes. Measured at 25 °C cold-acclimation results in O₂ uptakes slightly higher than in warm-acclimated snakes. The temperature sensitivity (Q₁₀) of aerobic metabolism in thus higher for the cold-acclimated snakes being 3.17 compared to 2.11 for the warmacclimated.O₂-Hb dissociation curves of whole blood from the two acclimation groups show a marked increase in O₂ affinity associated with cold-acclimation independent of blood pH. The shift in O₂ affinity correlates with a marked decrease in red cell organic phosphate concentration (ATP) in cold-acclimated snakes. The temperature sensitivity of the O₂-Hb binding expressed by the H values was rather uniform at about –11 kcal·mol^–1 (O₂) for both acclimation groups. The CO₂ Bohr factor in cold-acclimated blood at –0.55 was about double that in warm-acclimated. Then value for both acclimation groups increased with higher temperatures. Hematocrit and blood O₂ capacity were higher in the cold-acclimated snakes.The acclimation effects on O₂ uptake, O₂-Hb affinity and the Bohr effect, are opposite to those obtained earlier on reptiles at lower latitudes. It is discussed how a downward translation of the O₂ uptake-temperature curve and a high thermal sensitivity (Q₁₀) may be adaptive for species at latitudinal extremes where the active season is short and diurnal temperatures fluctuate widely. It is further discussed how a change in O₂ affinity by its influence on the capillary to cellular O₂ gradients may affect the aerobic metabolism.     

Suppressor mutations (rin) that specifically suppress the recA+ dependence of stable DNA replication in Escherichia coli K-12

Summary The sdrA102 mutation confers upon cells the ability to replicate DNA in the absence of protein synthesis. This mutation was combined with the recA200 mutation, which renders the recA protein thermolabile, and had little effect on normal replication. However, the sdrA102 recA200 double mutant exhibited temperature-sensitive stable DNA replication: it replicated DNA continuously in the presence of chloramphenicol at 30°C, whereas at 42°C DNA replication ceased after the DNA content increased only 40–45%. Suppressor mutants (rin; recA-independent) capable of stable DNA replication at 42°C were isolated from the double mutant. The suppressor mutant retained all other recA ^– characteristics, i.e., deficient general recombination, severe UV-sensitivity, and incapability of prophage induction in lysogens. This indicates that the rin mutation specifically suppresses the recA ⁺ dependency of stable DNA replication. It is suggested that the recA ⁺ protein stabilizes a specific structure, similar to an intermediate in recombination, which may function in the initiation of stable DNA replication.