Physiological Basis Of Variation Research Articles

Physiological evaluation of growth and yield variation of mustard (Brassica juncea) varieties under organic products in North-Western Indo-Gangetic Plains

A field experiment was conducted for two years to analyze the physiological basis of variation in the growth and yield of popular mustard varieties under organic production. Twelve mustard varieties of varied duration and agroclimatic suitability were evaluated in a randomized complete block design. Results revealed that varieties NRCHB-506, RH-406, and RGN-229, being at par, registered significantly maximum leaf area index, photosynthesis rate, and chlorophyll content at all the crop growth stages, i.e., 30, 60 and 90 DAS. During both the intervals, i.e., 30-40 and 80-90 DAS, variety RH-406 followed by RGN-229 registered maximum crop growth rate, whereas,in NRCHB-101, the lowest crop growth rate was observed. At each crop growth stage, photosynthesis rate has a significant positive correlation with leaf area index, chlorophyll content, crop growth rate during 30-40 and 80-90 DAS. Varieties Pusa Mustard-25 (5.8) and Pusa Mustard-26 (5.7) recorded significantly higher primary branches plant-1. However, varieties Pusa Tarak, RH-406, and RGN-229 recorded the significantly highest number of secondary branches plant-1. Being at par, varieties NRCHB-506, RH-406, RGN-229, and Pusa Bold recorded a significantly higher number of silique plant-1, seed yield,and stover yield than other varieties. The seed yield was found significantly and positively correlated with the crop growth rate at 80-90 DAS (r=0.600**), chlorophyll content at 90 DAS (r=0.558**), and silique plant-1(r=0.518**).Therefore, it is inferred that varieties like RH-406, RGN-229, and NRCHB-506 are suitable to grow under organic nutrient management in the prevailing agro-climatic conditions.

Molecular mechanisms of self-regulation in multiannual rodent populations: Experimental test of an updated hypothesis.

Edwards, P. D., Frenette-Ling, C., Palme, R., & Boonstra, R. (2021). Social density suppresses GnRH expression and reduces reproductivity in voles: A mechanism for population self-regulation. Journal of Animal Ecology, 90, 784-795. Intrinsic population processes are important in the regulation of populations of small rodents, including those which display multiannual cycles. By measuring reproductive parameters, faecal androgen metabolites, and gene expression and DNA methylation in the CNS of juvenile voles, this paper demonstrates that suppression of reproduction occurs in female voles at high density compared to low density in enclosures, and that this maternal, epigenetic effect is also apparent in their offspring. This suggsests that direct density dependence influences reproduction and, hence, immediate rate of population growth, while gene expression mediated by DNA methylation blocking transcription, may have a delayed density-dependent effect in juveniles. Both direct and delayed density dependence are necessary to generate multiannual population cycles. Edwards et al. (2021) break new ground in demonstrating the molecular and physiological basis of variation in population dynamics of small mammals ranging from multiannual cycles to stability that have fascinated researchers for nearly a century.

Genetic, molecular and physiological basis of variation in Drosophila gut immunocompetence.

Gut immunocompetence involves immune, stress and regenerative processes. To investigate the determinants underlying inter-individual variation in gut immunocompetence, we perform enteric infection of 140 Drosophila lines with the entomopathogenic bacterium Pseudomonas entomophila and observe extensive variation in survival. Using genome-wide association analysis, we identify several novel immune modulators. Transcriptional profiling further shows that the intestinal molecular state differs between resistant and susceptible lines, already before infection, with one transcriptional module involving genes linked to reactive oxygen species (ROS) metabolism contributing to this difference. This genetic and molecular variation is physiologically manifested in lower ROS activity, lower susceptibility to ROS-inducing agent, faster pathogen clearance and higher stem cell activity in resistant versus susceptible lines. This study provides novel insights into the determinants underlying population-level variability in gut immunocompetence, revealing how relatively minor, but systematic genetic and transcriptional variation can mediate overt physiological differences that determine enteric infection susceptibility.

A Quantitative Analysis of Growth and Size Regulation in Manduca sexta: The Physiological Basis of Variation in Size and Age at Metamorphosis.

Body size and development time are important life history traits because they are often highly correlated with fitness. Although the developmental mechanisms that control growth have been well studied, the mechanisms that control how a species-characteristic body size is achieved remain poorly understood. In insects adult body size is determined by the number of larval molts, the size increment at each molt, and the mechanism that determines during which instar larval growth will stop. Adult insects do not grow, so the size at which a larva stops growing determines adult body size. Here we develop a quantitative understanding of the kinetics of growth throughout larval life of Manduca sexta, under different conditions of nutrition and temperature, and for genetic strains with different adult body sizes. We show that the generally accepted view that the size increment at each molt is constant (Dyar’s Rule) is systematically violated: there is actually a progressive increase in the size increment from instar to instar that is independent of temperature. In addition, the mass-specific growth rate declines throughout the growth phase in a temperature-dependent manner. We show that growth within an instar follows a truncated Gompertz trajectory. The critical weight, which determines when in an instar a molt will occur, and the threshold size, which determines which instar is the last, are different in genetic strains with different adult body sizes. Under nutrient and temperature stress Manduca has a variable number of larval instars and we show that this is due to the fact that more molts at smaller increments are taken before threshold size is reached. We test whether the new insight into the kinetics of growth and size determination are sufficient to explain body size and development time through a mathematical model that incorporates our quantitative findings.

Physiological and genetic basis for variation in migratory behavior in the three-spined stickleback, Gasterosteus aculeatus

AbstractClosely related species of fish often exhibit different migration patterns. Even within species, anadromous and resident populations can be found in a diverse number of taxa. Although several environmental factors that regulate behavioral and physiological changes associated with fish migration have been identified, the genetic mechanisms underlying the variation in the ability to respond to these environmental cues in fishes that show different migratory behaviors are not well known. The three-spined sticklebackGasterosteus aculeatus(Linnaeus 1758) is a good model system for elucidation of the genetic basis for variation in migratory behaviors and other physiological changes associated with migration. First, the three-spined stickleback exhibits great inter-population variation in migration patterns. Second, genetic and genomic tools are now available for studying this species. In the present study, variation in the migration patterns amongG. aculeatuspopulations and the recent progress in our understanding of the genetic and physiological basis for variation in traits important forG. aculeatusmigration are reviewed.

Source - sink differences in genotypes and water regimes influencing sucrose accumulation in sugarcane stalks

Relatively little is known about the physiological basis for variation in sucrose content among sugarcane clones despite substantial research at the molecular and biochemical levels. We used irrigation and continuous monitoring of photosynthesis and plant extension rate to modify dry matter partitioning in four clones differing widely in sucrose content. Three pot experiments were conducted on two low sucrose content clones, KQ97-2599 and KQ97-2835, and two high sucrose content clones, Q117 and KQ97-5080, in a temperature-controlled glasshouse. As expected, sucrose content on a dry mass basis of whole stalks was greater in high (55% maximum) than in low sucrose clones (40% maximum), but sucrose content in the two clones selected for low sucrose reached 55% in some internodes. Differences between clones in whole-plant net photosynthesis and aerial biomass accumulation were small. However, biomass was distributed over fewer stalks in the high sucrose clones (4–7 stalks per pot) than in the low sucrose clones (9–11 stalks per pot). The high sucrose clones also allocated a considerably greater proportion of dry matter to the stalk (70% maximum) than the low sucrose clones (60% maximum). It is suggested that the relatively large amount of new leaf tissue produced by the high tillering, low sucrose clones placed an additional demand for structural photo-assimilate in these clones and delayed the accumulation of sucrose in the stalk. The results indicated that there is little direct genetic control on the maximum amount of sucrose that can accumulate in stalk tissue and that genetic contrasts in sucrose content reside more in the morphology of the plant and responses to ripening stimuli such as mild water stress, and how these traits influence supply and demand for photo-assimilate.

Characterization of novel inbred lines of white clover (Trifolium repens L.). II. Variation in N2 fixation, NO3- uptake and their interactions

N2 fixation, nitrate uptake, and tissue N levels werecompared in four novel self-fertile inbred lines (referred to as A, B, C andD) of white clover (Trifolium repens L.) believed to differ markedly intheir nitrogen relations. Plants were inoculated with a mixture of Rhizobiumstrains and grown in flowing nutrient solutions without mineral N for 18 dprior to supplying half the plants with 20 µM\(NO_3^ - \) over a 36 d treatment period. Net uptakeof \(NO_3^ - \) was measured automatically on a dailybasis. The remaining plants constituted ‘controls’ solely dependent uponN2 fixation for acquisition of N. Total uptake of\(NO_3^ - \) over 36 days was 27.4 (A), 23.8 (B), 13.8(C) and 30.1 (D) mmol N/plant, compared with N2 fixation of7.2 (A), 16.9 (B), 26.2 (C) and 6.2 (D) mmol N/plant by the\(NO_3^ - \)-fed lines. Total N2 fixationby corresponding ‘control’ plants was 15.6 (A), 35.6 (B), 35.3 (C) and 2.2(D) mmol N/plant. Line D plants exhibited a 3:1 segregation with respect toeither ‘nil’ or ‘partially impaired’ N2 fixation; thecorresponding ratio for line A was 1:3. Line C plants had a ‘low\(NO_3^ - \) uptake’ phenotype characterised by specific\(NO_3^ - \) uptake rates approximately half those ofthe other lines, higher N2 fixation in the presence of\(NO_3^ - \), and low leaf + petiole concentrations of\(NO_3^ - \), although concentrations of\(NO_3^ - \) in stolon and root fractions were similarin all lines. These inbred lines provide a tool for (1) the analysis of thegenetic and physiological basis of variation in the efficacy with which\(NO_3^ - \) uptake down-regulates N2fixation, and (2) testing ecological hypotheses for temporal and spatialvariation in clover/grass coexistence in pastures.

A physiological basis for variation in the contractile properties of isolated rat heart.

1. The maximum Ca(2+)-activated force, maximum velocity of unloaded shortening and both Ca(2+)- and actin-activated ATPase activities of myosin have been measured in detergent-skinned preparations of isolated bundles of rat right ventricle after exposure of the intact tissue to different conditions of superfusion, mechanical activity and temperature. 2. Maximum Ca(2+)-activated force per unit cross-sectional area decreases with increasing cross-sectional area, and, in the absence of electrical stimulation, with the duration of superfusion. Maximum velocity of unloaded shortening is not influenced by these differences. 3. Actin-activated ATPase activity of myosin decreases as cross-sectional area increases and duration of superfusion increases, but the extent of the decrease in enzymatic activity is less than that of developed force. Ca(2+)-activated ATPase activity is independent of these differences. 4. Actin-activated ATPase activity in cryostatic sections of quickly frozen tissue is not uniform across the transverse section. In thin bundles, it is highest in the centre and lowest at the edge of the section, which correspond, respectively, to the centre and the surface of the tissue bundle. Exposure of the tissue section to 1 microM-cyclic AMP increases the actin-activated ATPase activity of myosin with the largest increase in activity occurring at or near the surface of the bundle. 5. Ca(2+)-activated ATPase activity of myosin is uniform across the transverse section and is not changed by cyclic AMP. 6. Electrical stimulation, elevated Ca2+ concentration in the superfusion medium, or isoprenaline partially or completely reverse the decline in maximum Ca(2+)-activated force produced by prolonged superfusion of the bundle before its skinning. 7. These observations are similar in many ways to those made on frog skeletal muscles by Elzinga, Howarth, Rull, Wilson & Woledge (1989a). An explanation based on the existence of a physiological mechanism for regulating the properties of force generators is proposed. Regulation of the attachment of the cross-bridge to an actin filament may be the basis for the regulatory mechanism.

A physiological basis of variation in postcopulatory behaviour in a dragonfly Sympetrum obtrusum

A physiological basis of variation in postcopulatory behaviour in a dragonfly Sympetrum obtrusum

The physiological basis for variation in ovulation rate and litter size in sheep: A review

Variation in litter size of sheep can be determined by variation in both ovulation rate and embryo survival. This paper reviews the literature available on the extent of such variation and its causes. Embryo survival is inversely related to ovulation rate and shows genetic variation, but little definitive work has been undertaken to explain its physiological basis. Considerable research has been undertaken in the quest for hormonal correlates of ovulation rate by comparing patterns of hormone secretion in prolific and non-prolific breeds of ewe, but has yielded equivocal results. Manipulation of ovulation rate by using techniques such as immunization against ovarian steroids clearly suggest an involvement of the endocrine system in the determination of ovulation rate. The inability to show consistent relationships between quantitative measures of hormone secretion and ovulation rate may be attributable to the sensitivity of the techniques used to measure gonadotrophin status. In addition it may be confounded by variation in the sensitivity of ovarian follicles to gonadotrophin stimulation, a largely unexplored area.

The Progression Factor in Insect Growth

Previous articleNext article No AccessThe Progression Factor in Insect GrowthF. S. BodenheimerF. S. Bodenheimer Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 8, Number 1Mar., 1933 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/394427 Views: 4Total views on this site Citations: 14Citations are reported from Crossref PDF download Crossref reports the following articles citing this article:Sugihiko Hoshizaki Per‐stage growth rates of head and body sizes in scarab larvae (Coleoptera: Scarabaeidae) decrease across ontogeny following a species‐specific pattern, Entomological Science 23, no.44 (Sep 2020): 374–384.https://doi.org/10.1111/ens.12435Laura W. Grunert, Jameson W. Clarke, Chaarushi Ahuja, Harish Eswaran, H. Frederik Nijhout, Daniel Doucet A Quantitative Analysis of Growth and Size Regulation in Manduca sexta: The Physiological Basis of Variation in Size and Age at Metamorphosis, PLOS ONE 10, no.55 (May 2015): e0127988.https://doi.org/10.1371/journal.pone.0127988Alessandro Minelli, Giuseppe Fusco Arthropod Post-embryonic Development, (Apr 2013): 91–122.https://doi.org/10.1007/978-3-662-45798-6_5 Giuseppe Fusco , Nigel C. Hughes , Mark Webster , and Alessandro Minelli Exploring Developmental Modes in a Fossil Arthropod: Growth and Trunk Segmentation of the Trilobite Aulacopleura konincki. G. Fusco et al., The American Naturalist 163, no.22 (Jul 2015): 167–183.https://doi.org/10.1086/381042N. Gough, J.D. Brown Development of larvae of the whitefringed weevil, Graphognathus leucoloma (Coleoptera: Curculionidae), in northern Queensland, Bulletin of Entomological Research 81, no.44 (Jul 2009): 385–393.https://doi.org/10.1017/S0007485300031941G.Evelyn Hutchinson, Nils Tongring The possible adaptive significance of the Brooks-Dyar rule, Journal of Theoretical Biology 106, no.33 (Feb 1984): 437–439.https://doi.org/10.1016/0022-5193(84)90040-7V. B. Wigglesworth Growth, (Jan 1972): 61–145.https://doi.org/10.1007/978-94-009-5973-6_3A.L. Rice Growth ‘rules’ and the larvae of decapod crustaceans, Journal of Natural History 2, no.44 (Oct 1968): 525–530.https://doi.org/10.1080/00222936800771011 Stanley D. Beck Nutrition of the European Corn Borer, Pyrausta nubilalis (HBN.). II. Some Effects of Diet on Larval Growth Characteristics, Physiological Zoology 23, no.44 (Sep 2015): 353–361.https://doi.org/10.1086/physzool.23.4.30152093R. R. Lejeune The Effect of Jack-pine Staminate Flowers on the Size of Larvae of the Jack-pine Budworm, Choristoneura sp., The Canadian Entomologist 82, no.22 (May 2012): 34–43.https://doi.org/10.4039/Ent8234-2Laurence C. Woodruff The normal growth rate of Blattella germanica L., Journal of Experimental Zoology 79, no.11 (Aug 1938): 145–165.https://doi.org/10.1002/jez.1400790110P. A. Buxton Studies on the growth of Pediculus (Anoplura), Parasitology 30, no.11 (Apr 2009): 65–84.https://doi.org/10.1017/S0031182000010842W. Fulton Abercrombie Studies on cell number and the progression factor in the growth of Japanese beetle larvae (Popillia japonica Newman), Journal of Morphology 59, no.11 (Mar 1936): 91–112.https://doi.org/10.1002/jmor.1050590105William Trager The relation of cell size to growth in insect larvae, Journal of Experimental Zoology 71, no.33 (Oct 1935): 489–508.https://doi.org/10.1002/jez.1400710308