Modification of the properties of a translocation in the German cockroach by selection

Summary A stock of Blattella germanica bearing the interchange T(3; 12)/3;12 was subjected to close inbreeding with selection for random disjunction at metaphase I. After 3–4 generations of selection, interchange quadrivalent chiasma frequency decreased, variability in free bivalent chiasma frequency increased sharply, and individuals with either random or directed disjunction were present in the stock. Random disjunction was modified from a ratio of 2112 (adj.-1; alt.-1; adj.-2; alt.-2) to a ratio of 1111. After 7–8 generations of selection, chiasma frequency appeared to stabilize at lower than normal levels and variability decreased for both quadrivalents and free bivalents. Directed disjunction was modified from a ratio of 2114 to 1112, and no individuals with the original high level of directed disjunction were detected. Chains-of-four tended to orient randomly, especially in individuals where the ring quadrivalents showed directed disjunction. Relaxation of inbreeding, but not selection, produced an increase in chiasma frequency and variability in both free bivalents and quadrivalents, but the modified ratios for both random and directed disjunction were retained. These results are discussed with respect to inbreeding effects and genetic control of chiasma frequency and metaphase I disjunction in interchange quadrivalents.     

Sex determination in Sarotherodon (tilapia)

Summary The simplest possible model of the sex determination process adding autosomal influence to a minimal number of sex chromosomes was developed to explain matings of Tilapia (Sarotherodon) species. Eighteen different genotypes, each having two autosomes (AA, Aa, or aa) and two sex chromosomes (WX, WY, WW, XY, XX or YY) involved in sex determination, are predicted by the theory. Their sex (10 males and 8 females) were determined using a series of directed graphs, showing the relative strength of the chromosome pairs, developed on the basis of Chen's sex ratio results (Chen 1969). This theoretical model predicts eight different sex ratios (01, 13, 35, 11, 97, 53, 31, 10 ); three of them are not predicted by the WXYZ theory. The greatest part of these sex ratios have been obtained experimentally in extensive series of crosses between related species of Tilapia and their hybrids, carried out by several authors. The theory succeeds in explaining all of Chen's results, including those ratios 53 and 01 seen in certain crosses but not predicted by the WXYZ theory. The importance of the autosomes is seen in comparisons of the genotype pairs (AaWY, aaWY), (AaXY, aaXY) and (AAWW, AaWW) in which the first genotype in each case is male while the second is female as proven by the sex ratio results. The members of the pair differ only in the substitution of one autosome for the other. To test the theory, experiments consisting of hormonal sex reversion and a series of crosses are proposed. Finally, theoretical and practical implications of the theory are discussed.     

Cellular fatty acid composition of six fastidious,gramnegative, xylem-limited bacteria from plants

Composition of cellular fatty acids was determined for strains of fastidious, Gramnegative, xylem-limited bacteria causing or associated with Pierce's disease of grapevine, phony disease of peach, plum leaf scorch, stunt of ragweed, elm leaf scorch, and periwinkle wilt. The most abundant fatty acids were straight-chain 150, 160, 170, and 180, unsaturated 161, 181, and unsaturated 17-and 19=carbon homologs. Minor fatty acids included straightchain 120, 140, 190, and 200; an unsaturated 15-carbon homolog; hydroxy-substituted 2-OH 120, 3-OH 120, and 3-OH 140; and branched chain iso-140 and iso-200. Cyclopropane acids were not detected. Physiological age had no effect on fatty acid composition. Class analysis of data indicated relative uniformity within the group. Saturated even-carbon chains comprised 31%–42%, unsaturated acids 41%–52%, saturated odd-carbon chains 10%–18%, hydroxysubstituted chains 2%–7%, and branched-chains 1%–4% of total fatty acids. The ratio of saturated-unsaturated acids ranged from 0.8 to 1.2.     

Osmotropotaxis inDrosophila melanogaster

Summary Drosophila melanogaster is able to perform osmotropotaxis under open-loop conditions. With an optimal stimulus the average turning tendency to the side of higher concentration corresponds to a circular track with radiusr=0.8 cm. The response amplitude does not decrease within 1 or 2 h. Unilaterally antennectomized flies in an homogeneous odor field show a permanent turning tendency towards their intact side.The smallest concentration ratio to elicit osmotropotaxis in normal flies ranges between 610 and 910 at high and between 210 and 510 at an about 50 times lower odor intensity. No negative tropotaxis (i.e. turning to the side of lower concentration) is observed, even with strong repellents.     

Rhythmicity of swimming activity in an axenic population of Paramecium multimicronucleatum

A unicellular organism, Paramecium, exhibits circadian rhythm activities in many physiological phenomena, i.e., mating reactivity, photoaccumulation in Paramecium bursaria and mating type reversals in Paramecium multimicronucleatum. In this study, we used an image-processing system to analyze swimming activity in a population of Paramecium multimicronucleatum cultured axenically under 12 h-light/12 h-dark cycles (LD 1212). Swimming behavior was recorded both under LD 1212 and constant darkness and images tracing the tracks of Paramecium were produced every 4 min. Swimming activity was represented by the occupied area by the tracks relative to the total observed area. It is high during daytime and low at night and exhibits a freerunning rhythm in constant darkness. Furthermore, criteria for two major components of swimming behavior, straight and circle swimming, were established and analyzed. The results indicate that swimming behavior alters depending on the time of day: straight swimming increased during the day and circling was dominant around dusk both under LD 1212 and constant darkness.Abbreviations ZT Zeitgeber Time - LD 1212 12h- light/12h-dark cycles - TF transversing frequency     

Nutrient proportions in foliage of semi-mature loblolly pine

Summary Nitrogen and phosphorus limitations to growth are common in many loblolly pine (Pinus taeda) stands. Interactions of these nutrients may complicate interpretation of foliar nutrient analysis for predicting response to forest fertilization. Proportions of foliar nutrient concentrations (and the changes in these proportions following fertilization) were examined in 36 semi-mature loblolly pine plantations in the southeastern United States. Mean proportions of nutrient concentrations (NPKCaMg) for non-fertilized stands were 1009.336.517.29.2. Potassium and phosphorus were higher. Nitrogen fertilization generally decreased the PN ratio and enhanced growth, indicating a nitrogen deficiency in most stands under study. Additions of nitrogen and phosphorus together yielded a significant increase in the PN ratio. Effects of fertilization effects on other nutrient concentration ratios were also examined.Paper No. 9401 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27695.     

The effect of photoperiod on daily rhythms of Oxygen consumption in the tropical toad,Bufo marinus

Summary Oxygen consumption was measured with an automatic continuously recording electrolysis system in toads acclimated at 15° C and under photoperiods of LD 816, 1212, 168, 66, 231 and LL and DD. All groups exposed to LD had pronounced significant daily rhythms with a trough near the onset of the photophase and a peak at the beginning of the scotophase (Figs. 1–3, 9, 10), while no rhythms were detected in animals exposed under free-running conditions of constant light (Figs. 6–7) or constant darkness (Fig. 8), even on the first day under LL or DD. These rhythms are thus shown to be non-circadian, since they do not persist in freerunning conditions of up to 45 days. Some preliminary evidence from studies on locomotor activity (Figs. 12, 13) indicates that the daily rhythm in metabolic rate may be independent of the locomotor activity cycle. The difference in the rate of oxygen consumption during peak and low hours of each daily cycle is defined as the daily routine metabolic scope, which may be more useful in ecological studies of animal energetics than the difference between the minimum and a forced maximum metabolic rate. No correlations were found between daily changes in atmospheric pressure and cycles of oxygen consumption.This work was supported by a grant from the National Science Foundation (GB-3574) and a University of Rhode Island Research Committee Grant-in-aid. We are grateful to Robert Cubert for aid in designing and constructing the electrolysis system and for assistance with computer programs.     

Glycerolipid-fatty-acid desaturase deficiencies in chloroplasts from fruits of Capsicum annuum L.

Chloroplasts from fruits and leaves of Capsicum annuum cv. Bell Tower were purified on sucrose gradients, and the lipids were separated by column and thin-layer chromatography. The glycerolipids mono- and digalactosyldiacylglycerol (MGDG, DGDG), sulfoquinovosyldiacylglycerol (SQDG), and phosphatidylglycerol (PG) were quantified, and the fatty-acid composition at the 1 and 2 positions of the glycerol moiety (sn-1 and sn-2) was determined after hydrolysis with position-specific lipases. In fruit chloroplasts, ³-trans hexadecenoate (trans-3-161) was absent and replaced by palmitate (160) at sn-2 of PG, and ^7,10,13-hexadecatrienoate (163) at sn-2 of MGDG was greatly reduced and largely replaced by linoleate (182). The ratio of 182 to linolenate (183) was consistently greater in glycerolipids from fruit compared with leaf chloroplasts. The lower percentage of C-16 fatty acids at sn-2 indicated that prokaryotic molecular species were reduced by 15% in DGDG, 40% in SQDG, and 90% in MGDG, in fruit compared with leaf chloroplasts. The MGDGDGDG ratios in fruit and leaf chloroplasts were 1.21 and 2.21, respectively. Taken together, the data indicate that chloroplasts in Capsicum fruit are deficient in three desaturases: those that convert 1) 160 to ³-trans-161 at sn-2 of PG, 2) 160 to ⁷–cis-161 at sn-2 of MGDG, and 3) 182 to 183 at both sn-1 and sn-2 of various chloroplast glycerolipids.Abbreviations Chl chlorophyll - DGDG digalactosyldiacylglycerol - FS free sterol - GL galactolipid - MGDG monogalactosyldiacylglycerol - PE phosphatidyl ethanolamine - PG phosphatidylglycerol - PL phospholipid - SQDG sulfoquinovosyldiacylglycerol We are grateful to Dr. Roger Calza for providing us with the tobacco gt11 cDNA expression library and to Dr. Eric Huttner for his advice throughout the screening procedure. We also wish to thank M. Gosse for his assistance in growing and maintaining our plants. T.W.B. was supported by a BAP research grant from the Commission of the European Communities.     

Effect of light-dark cycles with different LD time-ratios and different LD intensity-ratios on the activity rhythm of chaffinches

Summary Chaffinches (Fringilla coelebs L.) were kept at light-dark (LD) cycles with two different light intensity ratios (ca. 500.1 and ca. 101 lux) both with 1.83 hours of twilight at the onset and end of light time. The light time/dark time ratio (LD time-ratio) was varied in the range from 420 to 222 hours.Birds at the high LD intensity-ratio (500.1 lux) increased activity time () with increasing light time from LD 420 to 222. Time of activity onset, middle, and end of activity corresponded to onset, middle, and end of light time from LD 420 to 168, but the phase angles of middle and end of activity (related to midpoint of light time and midpoint of artificial dusk respectively) became more positive (advanced) at LD 204 and 222.Birds at the lower LD intensity-ratio (101 lux) increased activity time with increasing light time from LD 816 to 204 but activity time at LD 420 was equivalent to that at LD 816. The phase angles of activity onset and middle (related to midpoint of artificial dawn and midpoint of light time, respectively) became more positive at both long (LD 204) and short (LD 420) light times.By use of different twilight regimes (linear and logarithmic changes in intensity), it was shown that end of activity was more closely related with the rate of change and/or absolute level of light intensity than was onset of activity.During January and February, the birds responded to increased LD time-ratios by an increase of activity time and by strong positive phase angle shifts which correspond to observations of activity patterns of chaffinches exposed to outdoor conditions during the spring breeding season.The free-running circadian periods () of 6 birds measured at 15 lux at the end of the experiments following LD 204 averaged 22.17 hours.From the data on precision, i. e. the period-to-period variation in the phase angles of single birds averaged over all birds of one group and condition, as well as from the number of birds not synchronized with the LD cycles, it is concluded that extreme long and short light times per 24 h represent weaker zeitgebers compared to LD cycles with medium lengths of light time. Likewise, LD cycles with low LD intensity-ratios are weaker zeitgebers than LD cycles with high LD intensity-ratios.This study was carried out while the senior author was on sabbatical leave from the University of Alaska and held a fellowship from the Alexander von Humboldt Stiftung.     

Brain-gonad axis and photoperiodically-stimulated sexual maturation in the slug,Limax maximus

Summary Physiological and endocrine mechanisms mediating long-day (LD 168) triggered sexual maturation were studied in the terrestrial slug,Limax maximus. Our findings were: (1) Maturation was induced in immature slugs seeing only short days (LD 816) after implantation of whole brains from maturing donors, but no development was found in sham-operated control slugs or in animals receiving implants of muscle from mature donors (Table 1). (2) Removal of the optic tentacles did not block maturation in LD 168 or promote maturation in LD 816 (Fig. 1). (3) Gonadectomy (castration) abolished penis development in 9 of 11 slugs exposed to LD 168 for periods of up to 31 weeks (Table 2). The results are consistent with a model forLimax reproductive tract development in which the perception of long days by extraocular receptors results in the secretion of a maturation hormone by the brain followed by the production of a separate male-phase sex hormone by the developing gonad.Abbreviations ASO accessory sex organs - DB dorsal bodies - FPSH female-phase sex hormone - MH maturation hormone - MPSH male-phase sex hormone This work was supported in part by grants from NSF (BNS 78-01408) and NIH (MH 27948) to P.G.S. The assistance of Mr. T.M. Gordon, Mr. J.L. Broyles, and Mr. M. Bullock is gratefully acknowledged.     

Average phase difference theory and 1∶1 phase entrainment in interlimb coordination

The dynamics of coupled biological oscillators can be modeled by averaging the effects of coupling over each oscillatory cycle so that the coupling depends on the phase difference between the two oscillators and not on their specific states. Average phase difference theory claims that mode locking phenomena can be predicted by the average effects of the coupling influences. As a starting point for both empirical and theoretical investigations, Rand et al. (1988) have proposed d/dt= — K sin ), with phase-locked solutions =arcsin( /K), where is the difference between the uncoupled frequencies and K is the coupling strength. Phase-locking was evaluated in three experiments using an interlimb coordination paradigm in which a person oscillates hand-held pendulums. was controlled through length differences in the left and right pendulums. The coupled frequency _c was varied by a metronome, and scaled to the eigenfrequency _v of the coupled system K was assumed to vary inversely with _c. The results indicate that: (1) and K contribute multiplicatively to (2) =0 or = regardless of K when =0; (3) 0 or regardless of when K is large (relative to ); (4) results (1) to (3) hold identically for both in phase and antiphase coordination. The results also indicate that the relevant frequency is _c/_v rather than _c. Discussion high-lighted the significance of confirming =arcsin(/K) for more general treatments of phase-locking, such as circle map dynamics, and for the 11 phase-entrainment which characterizes biological movement systems.     

The mucin profiles of normal gastric mucosa, intestinal metaplasia and its variants and gastric carcinoma

Summary Human gastrectomy specimens, including 48 carcinomas and 25 selected benign cases showing extensive intestinal metaplasia (IM), were examined in detail histologically and histochemically. IM was classified into complete (type I), incomplete without sulphomucins (type IIA) and incomplete with sulphomucins (type IIB). Type IIB was associated with intestinal but not diffuse cancers (P<0.01) or benign lesions (P<0.01). The mucin profiles of IIB IM were similar to intestinal cancers with sulphomucins predominating overN-acetylsialomucins.O-acetylsialomucins were not seen in IIB IM or tumours but were observed in complete or type IIM. These findings suggest a histogenic link between incomplete IM secreting sulphomucins (or colonic metaplasia) and intestinal cancers of the human stomach.     

Circadian periodicity and the initiation of gonadal growth in male blackheaded buntings (Emberiza melanocephala)

Summary Photosensitive male blackheaded buntings were held under six different light cycles consisting of a 6-hour main photophase coupled with scotophases of various durations (6L/6 (2 n+1) D). Testicular growth was stimulated in buntings by cycle lengths of 12-(6L6D), 36-(6L30D) and 60-hours (6L54D), but not by cycles of 24-(6L18D), 48-(6L42D) and 72-hours (6L66D). These results are consistent with the Bünning hypothesis and indicate that an endogenous rhythm with a period of approximately 24 hours plays a role in the initiation of testicular growth in this bird.Abbreviations CTW combined testicular weight - D dark phase (scotophase) - L light phase - n number of multiples of 6 D     

Streptomycin resistance is inherited as a recessive Mendelian trait in a Nicotiana sylvestris line

Summary The SR180 cell line has been isolated in a callus culture derived from a haploid Nicotiana sylvestris (n = X = 12) plant by its ability to proliferate on a selective medium containing 2,000 g/ml streptomycin sulphate. From the cell line diploid plants have been regenerated. The SR180 selfs are resistant to streptomycin. Streptomycin sensitivity in F1, and a 31 (sensitive to resistant) segregation in F2 indicate that resistance in the SR180 mutant is the result of a recessive Mendelian mutation.     

Genetics of fertility restoration in hybrid rice

Summary The cross combination involving 14 male-sterile lines in rice, when crossed with different maintainers, showed fertility restoration in certain combinations. When F₂ segregating populations were classified based on spikelet fertility, fertility restoration was shown to be governed by 31, 9331, and 1231, due to allelic differences. This indicated that the cytosterility of the same group showed monogenic fertility restoration, whereas crossing plants belonging to different cystosterile groups showed a digenic pattern of segregation.     

Physiologic,morphologic and behavioral responses of perpetual cultures ofCaulobacter crescentus to carbon,nitrogen and phosphorus limitations

Perpetual cultures ofCaulobacter crescentus were maintained in a chemostat and provided with media that provided glucose, glutamate, ammonium chloride, and Na/K phosphate as sources, respectively, of C, of C and N, of N and of P. All cultures were maintained at the same relative flow rate, f/V, so that reproductive rate was constant. As the CNP ratio was shifted from a balanced ratio of 100 g C9–10 g N1 g P, the cells modulated their rates of uptake, reducing the rates of uptake of excess element-sources and accelerating the uptake of potential sources of the limiting element. The change in N-limited cells was the greatest, resulting in a nearly 150-fold increase in rate of uptake of amino acids. Poly--hydroxybutyrate or polyphosphate was stored whenever C or P, respectively, was not the limiting element. Direct measurement of cell and stalk surface areas on purified peptidoglycan sacculi of P-limited cells revealed that the surface of both swarmer and stalked cells, as well as the stalk surface, participated in the accelerated rate of phosphate uptake. Swarmers from N-limited populations were the only cells that exhibited chemotactic responsiveness-to methionine, NH₄Cl and glutamate, but not to glucose or phosphate-sufficient to be detectable in a microcapillary assay. In populations that were C-limited and provided with ammonium ions as the principal source of N, morphogenesis and reproduction deteriorated and a steady state could not be maintained. Generally, the responses ofC. crescentus were appropriate to manage unbalanced nutrient supplies, but this oligoheterotrophic organism did not tolerate excesses of inorganic nutrients when limited for its sources of C, of energy, and of ammonium acceptor.     

Comparative mapping in F2∶3 and F6∶7 generations of quantitative trait loci for grain yield and yield components in maize

This study was conducted to compare maize quantitative trait loci (QTL) detection for grain yield and yield components in F₂₃ and F₆₇ recombinant inbred (RI) lines from the same population. One hundred and eighty-six F₆₇ RIs from a Mo17×H99 population were grown in a replicated field experiment and analyzed at 101 loci detected by restriction fragment length polymorphisms (RFLPs). Single-factor analysis of variance was conducted for each locus-trait combination to identify QTL. For grain yield, 6 QTL were detected accounting for 22% of the phenotypic variation. A total of 63 QTL were identified for the seven grain yield components with alleles from both parents contributing to increased trait values. Several genetic regions were associated with more than one trait, indicating possible linked and/or pleiotropic effects. In a comparison with 150 F₂₃ lines from the same population, the same genetic regions and parental effects were detected across generations despite being evaluated under diverse environmental conditions. Some of the QTL detected in the F₂₃ seem to be dissected into multiple, linked QTL in the F₆₇ generation, indicating better genetic resolution for QTL detection with RIs. Also, genetic effects at QTL are smaller in the F₆₇ generation for all traits.Abbreviations RFLPs Restriction fragment length polymorphisms - QTL quantitative trait loci - RIs recombinant inbreds Journal Paper no. J-16261 of the Iowa Agric and Home Economics Exp Stn Project no. 3134     

Photoperiodic induction of the first and the second diapause in the bean bug,Riptortus clavatus: a photoperiodic history effect

Summary In nondiapause adults raised under a long-day photoperiod, the critical daylength for diapause induction was between 13 and 14 h although some individuals did not respond to the short-day photoperiod and went on laying eggs. In postdiapause adults in which LD 1311 induced the first diapause (L13 insects), the critical daylength for diapause reinduction was between 13 and 14 h, whereas it was between 12 and 13 h in postdiapause adults in which LD 1014 induced the first diapause (L10 insects). Under LD 1311, a small proportion of L10 insects went into the second diapause after great delay as compared with L13 insects. Under LD 1014, on the other hand, L10 insects went into the second diapause more rapidly than L13 insects. Therefore, the photoperiod which had induced the first diapause affected the photoperiodic induction of the second diapause not only in the critical daylength but also in the speed of response. In Riptortus clavatus, the photoperiodic history influences the subsequent photoperiodic response even after a physiological state induced by the previous photoperiod was terminated completely.Abbreviations L13 insects postdiapause adults in which LD 1311 induced the first diapause - L10 insects postdiapause adults in which LD 1014 induced the first diapause     

A linkage map with RFLP and isozyme markers for almond

Inheritance and linkage studies were conducted with seven isozyme genes and 120 RFLPs in the F₁ progeny of a cross between almond cultivars Ferragnes and Tuono. RFLPs were detected using 57 genomic and 43 cDNA almond clones. Eight of the cDNA probes corresponded to known genes (extensin, prunin (2), -tubulin, endopolygalacturonase, oleosin, actin depolymerizing factor and phosphoglyceromutase). Single-copy clones were found more frequently in the cDNA (65%) than in the genomic libraries (26%). Two maps were elaborated, one with the 93 loci heterozygous in Ferragnes and another with the 69 loci heterozygous in Tuono. Thirty-five loci were heterozygous in both parents and were used as bridges between both maps. Most of the segregations (91%) were of the 11 or 1111 types, and data were analyzed as if they derived from two backcross populations. Eight linkage groups covering 393 cM in Ferragnes and 394 in Tuono were found for each map. None of the loci examined in either map was found to be unlinked. Distorted segregation ratios were mainly concentrated in two linkage groups of the Ferragnes map.     

The effect of some macronutrients on adventitious root development on scion apple cultivars in vitro

The influence of some macronutrients, especially NH₄NO₃ and KNO₃, on root development of microcuttings from 3 apple scion cultivars is discussed. A reduction of the level of NH₄NO₃ in the medium from full strength to 1/4 strength significantly increased the percentage rooting of Gala and Royal Gala, but not Jonagold. Further reduction of NH₄NO₃ level from 1/4 strength to zero significantly reduced the percentage of rooting in Gala but not Royal Gala. Jonagold rooted best at zero concentration NH₄NO₃. Without NH₄NO₃, rooting percentages were as high as 100% for all 3 cultivars when KNO₃ was provided at full strength. The results show that adventitious roots can be induced on apple scion cultivars by media manipulation.