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1.
Homozygous mt?/mt? diploid clones of the Closterium ehrenbergii Menegh. ex Ralfs species complex were obtained by hypertonic treatment from minus vegetative cells, and mating type segregation ratios in the F1 progeny of “triploid” zygospores between wild type mt+ haploid and mt?/mt? homozygous diploui were analyzed. The ratio of plus to minus individuals was 1:4.8, and the ratio of the pairs of opposite mating types to those of minus mating type was 1:2.1. The results clearly show that mt? is dominant to mt+ and that the mating type inheritance in these zygospores follows the triploid-like pattern. The validity of our assumption that the two mating types are determined by one genetic factor (mt? allele dominant) was confirmed in B1 progeny analyses as well. The results suggest that this sex determining mechanism is working effectively in the C. ehrenbergii species complex, in which several biological species have evolved through polyploidization. 相似文献
2.
P. T. Nikolaïdis 《Human physiology》2011,37(5):636-641
Despite the recognition of the beneficial role of cardiorespiratory power (CRP) for health and sport performance, the development
of this physical fitness parameter in adolescent soccer players was not well studied. Aim of this cross-sectional study was
to investigate the effect of age on CRP of adolescent soccer players, the influence of anthropometric characteristics and
body composition on it, and to establish normative data. Male adolescent (N = 274; aged 12.07–20.98 y), classified in nine one-year age-groups, child (N = 12, aged 7.71–11.8 y) and adult players (N = 22; aged 21.12–31.59 y), all members of competitive soccer clubs, were examined for anthropometric characteristics and
body composition and they performed Physical Working Capacity in heart rate 170 test (PWC170) on cycle ergometer. Analysis of variance revealed significant difference between age groups with respect to PWC170 in absolute
(F
10,.297 = 29.58, P < 0.001, η2 = 0.5), relative to body mass (F
10,.297 = 5.28, P < 0.001, η2 = 0.15) and relative to fat free mass values (F
10.297 = 4.98, P < 0.001, η2= 0.14). In addition, age was in positive association with these parameters (r = 0.6, P < 0.001, r = 0.24, P < 0.001 and r = 0.23, P < 0.001, correspondingly). The main finding of this study was that CRP increased during developmental period in soccer players,
even when it was adjusted to body mass or FFM, which increased during development. This documentation of the development of
CRP provided useful tool for coaches and fitness trainers in order to apply optimal exercise interventions for health and
performance. 相似文献
3.
Wild-type strains of the interfertile species Chlamydomonas eugametos (UTEX 9 and 10) and Chlamydomonas moewusii (UTEX 96 and 97) male readily and reciprocally; however, considerable lethality occurs among F1 hybrid meiotic products. We prepared two hybrid backcross lineages using C. eugametos and C. moewusii. One lineage began with the cross C. eugametos mating-type-plus (mt+) × C. moewusii mating-type-minus (mt?). An F1 mt+ hybrid from this cross was back-crossed to C. moewusii mt?, and a B1 mt+ hybrid was recovered. The B1 hybrid was again backcrossed to C. moewusii mt?, and this process was repeated through the fifth backcross. The other backcross lineage began with the reciprocal cross C. moewusii mt+× C. eugametos mt? and employed C. eugametos as the recurring mt? parent. This lineage also was continued through the fifth backcross. Meiotic product survival in the reciprocal interspecific crosses was less than 10%. In successive back-cross generations associated with both lineages, this value increased progressively to a maximum of 85–90%, the level observed for the intraspecific crosses. These results are consistent with the hypothesis that multiple genetic differences exist between C. eugametos and C. moewusii and that these are the major source of meiotic product lethality associated with the interspecific crosses. The inheritance of chloroplast genetic markers for resistance to streptomycin (sr-2) and for resistance to erythromycin (er-nM1) was also scored w the interspecific crosses and in the backcrosses. Most hybrid zygospores transmitted the resistance markers of the mt+ parent only, or of both parents, with the former zygospore type being more common. Although the intraspecific C. eugametos and C. moewusii crosses differ conspicuously with respect to the fraction of zygospores which transmit chloroplast genetic markers of both parents, the inheritance of chloroplast genetic markers in the interspecific crosses and backcrosses at' scribed here failed to clarify the genetic basis for this difference. 相似文献
4.
Alessandro Protti Francesco Fortunato Maria L. Caspani Mauro Pluderi Valeria Lucchini Nadia Grimoldi Luigi P. Solimeno Gigliola Fagiolari Patrizia Ciscato Samis M. A. Zella Maurizio Moggio Giacomo P. Comi Luciano Gattinoni 《PloS one》2014,9(5)
Platelets can serve as general markers of mitochondrial (dys)function during several human diseases. Whether this holds true even during sepsis is unknown. Using spectrophotometry, we measured mitochondrial respiratory chain biochemistry in platelets and triceps brachii muscle of thirty patients with septic shock (within 24 hours from admission to Intensive Care) and ten surgical controls (during surgery). Results were expressed relative to citrate synthase (CS) activity, a marker of mitochondrial density. Patients with septic shock had lower nicotinamide adenine dinucleotide dehydrogenase (NADH)/CS (p = 0.015), complex I/CS (p = 0.018), complex I and III/CS (p<0.001) and complex IV/CS (p = 0.012) activities in platelets but higher complex I/CS activity (p = 0.021) in triceps brachii muscle than controls. Overall, NADH/CS (r2 = 0.00; p = 0.683) complex I/CS (r2 = 0.05; p = 0.173), complex I and III/CS (r2 = 0.01; p = 0.485), succinate dehydrogenase (SDH)/CS (r2 = 0.00; p = 0.884), complex II and III/CS (r2 = 0.00; p = 0.927) and complex IV/CS (r2 = 0.00; p = 0.906) activities in platelets were not associated with those in triceps brachii muscle. In conclusion, several respiratory chain enzymes were variably inhibited in platelets, but not in triceps brachii muscle, of patients with septic shock. Sepsis-induced mitochondrial changes in platelets do not reflect those in other organs. 相似文献
5.
Jessica L. Burpee Elise L. Bardsley Richard M. Dillaman Wade O. Watanabe Stephen T. Kinsey 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2010,180(7):967-977
White muscle (WM) fibers in many fishes often increase in size from <50 μm in juveniles to >250 μm in adults. This leads to
increases in intracellular diffusion distances that may impact the scaling with body mass of muscle metabolism. We have previously
found similar negative scaling of aerobic capacity (mitochondrial volume density, V
mt) and the rate of an aerobic process (post-contractile phosphocreatine recovery) in fish WM. In the present study, we examined
the scaling with body mass of oxygen consumption rates of isolated mitochondria (VO2mt) from WM in three species from different families that vary in morphology and behavior: an active, pelagic species (bluefish,
Pomatomus saltatrix), a relatively inactive demersal species (black sea bass, Centropristis striata), and a sedentary, benthic species (southern flounder, Paralichthys lethostigma). In contrast to our prior studies, the measurement of respiration in isolated mitochondria is not influenced by the diffusion
of oxygen or metabolites. V
mt was measured in WM and in high-density isolates used for VO2mt measurements. WM V
mt was significantly higher in the bluefish than in the other two species and VO2mt was independent of body mass when expressed per milligram protein or per milliliter mitochondria. The size-independence of
VO2mt indicates that differences in WM aerobic function result from variation in V
mt and not to changes in VO2mt. This is consistent with our prior work that indicated that while diffusion constraints influence mitochondrial distribution,
the negative scaling of aerobic processes like post-contractile PCr recovery can largely be attributed to the body size dependence
of V
mt. 相似文献
6.
When mating-type minus (mt−) and plus (mt+) cells of theClosterium peracerosum-strigosum-littorale complex were mixed together in a nitrogen-deficient mating medium, cells of both types released protoplasts, this release
being the first step in the process of conjugation. Release of protoplasts by mt− cells also proceeded without pairing in a medium in which mt− and mt+ cells had previously been cultured together. A protein with the ability to induce the release of protoplasts was purified
from this medium by sequential column-chromatographic steps, and named PR-IP (protoplast-release-inducing protein). The PR-IP
had an apparent molecular mass (Mr) of 95000 on gel filtration and could be separated into several isoforms by anion-exchange chromatography. Each isoform consisted
of two glycopolypeptides of Mrs 42000 and 19000, while the deglycosylated polypeptides had Mrs of 34000 and 18000, respectively. From an analysis of dose-response curves, the numbers of PR-IP molecules required for
the release of a protoplast by a single cell was calculated as 1.5·109 and the concentration required for 50% of the maximum response (ED50) as 4.1·10−9M. We suggest that the PR-IP is a biologically active glycoprotein which induces the release of gametic protoplasts from mt− cells of thisClosterium complex. 相似文献
7.
Atlantic salmon Salmo salar eggs derived from a single family were incubated at two different water temperature regimes, with a mean temperature between fertilization and first feeding differing between 6 and 10° C (HT) and 2–6° C (LT). From first feed the fry were kept under the same rearing conditions and fed either high (50%) or low (45%) protein diet level of equivalent energy content until smoltification. All treatments were carried out in duplicate tanks. At first feeding the groups were similar in mass, but thereafter the HT‐fish were heavier and longer compared to the LT‐fish throughout the experiment. The groups fed the high protein diet were significantly heavier and longer compared with the corresponding low protein diet. A strong positive relationship was observed between LF and total white muscle cross‐sectional area (CSA), white muscle fibre diameter and fibre number. There were also equivalent relationships with body mass. There were no significant differences in CSA, the mean diameter or the number of white muscle fibres per CSA between groups at first feed. Muscle fibre number and CSA increased in all groups during the experiment, whereas fibre diameter reached a plateau when the fish reached > 9 cm LF. There were only minor effects of pre‐hatch and yolk sac stage temperature on CSA and fibre number per CSA during the juvenile stage. In short periods the LT‐group had larger CSA and higher fibre number than the HT‐groups, but this differences had disappeared by the end of the juvenile stage. No differences in mean fibre diameter were found between groups, except at the time of smoltification. When the fish approached smoltification a decrease in mean fibre diameter and an increase in muscle fibres <25 µm was seen and taken as an indication of recruitment of new fibres (hyperplasia). Only minor differences in CSA, fibre number or fibre diameter was observed between high and low protein diet groups. 相似文献
8.
Non-uniformity of fascicle parameters (fascicle lengths and orientation) within one skeletal muscle is well known. These parameters
have an effect on the physiological cross-sectional area and lengthening rate of the skeletal muscle. Using a binocular microscope
with a table driver (q- and p-axes) and vertical drive (v-axis) as a tool for reconstruction of the spatial orientation of single muscle fascicles, we developed an approach for three-dimensional
analysis of the arrangement and length distribution in the skeletal muscle of small mammals. Two subunits of the triceps brachii
muscle of the Galea musteloides forelimb, triceps longum and triceps laterale, were quantified and compared. Our data show that in the triceps laterale the
fascicles are significantly longer (10.23 mm, SD=1.19, n=41) than those in the triceps longum (6.58 mm, SD=2.88, n=39). In the triceps laterale, the fascicle orientation is more or less uniform, whereas, in the triceps longum, there are
two areas with different orientation of fascicles: anterior and posterior ones. Different inner architecture of the subunits
can be interpreted as an adaptation to the main locomotory function of the triceps muscle, namely production of propulsive
force during limb transfer phase and keeping dynamic stability during stance phase. Comparison of our data on the fascicle
length and geometry with our previous histochemical results on G. musteloides, shows that the anterior region of the triceps longum, which differs in the fascicle orientation, also contains a significantly
larger percent of slow muscle fibres. It is hypothesised here that this small region is involved in keeping posture.
Accepted: 16 May 2000 相似文献
9.
In order to identify a high carbon-sequestering microalgal strain, the physiological effect of different concentrations of carbon sources on microalgae growth was investigated. Five indigenous strains (I-1, I-2, I-3, I-4 and I-5) and a reference strain (I-0: Coccolithus pelagicus 913/3) were subjected to CO2 concentrations of 0.03–15% and NaHCO3 of 0.05–2 g CO2 l–1. The logistic model was applied for data fitting, as well as for estimation of the maximum growth rate (μmax) and the biomass carrying capacity (Bmax). Amongst the five indigenous strains, I-3 was similar to the reference strain with regards to biomass production values. The Bmax of I-3 significantly increased from 214 to 828 mg l–1 when CO2 concentration was increased from 0.03 to 15% (r = 0.955, P = 0.012). Additionally, the Bmax of I-3 increased with increasing NaHCO3 (r = 0.885, P = 0.046) and was recorded at 153 mg l–1 (at 0.05 g CO2 l–1) and 774 mg l–1 at (2 g CO2 l–1). Relative electron transport rate (rETR) and maximum quantum yield (Fv/Fm) were also applied to assess the impact of elevated carbon sources on the microalgal cells at the physiological level. Isolate I-3 displayed the highest rETR confirming its tolerance to higher quantities of carbon. Additionally, the decline in Fv/Fm with increasing carbon was similar for strains I-3 and the reference strain. Based on partial 28s ribosomal RNA gene sequencing, strain I-3 was homologous to the ribosomal genes of Chlorella sp. 相似文献
10.
D. WILSON 《The Annals of applied biology》1975,79(1):67-82
Lolium perenne selection lines with high calculated stomatal resistances to diffusion (rs) as a result of either few or short stomata, maintained leaf extension rates and photosynthetic rates longer than selection lines with low resistances when deprived of water. There were no significant differences between high and low rs plants in light saturated CO2 uptake of turgid attached leaves. When grown in soil drying to 21% moisture, plants with low calculated rs exhibited lower minimum leaf resistances (rl) than those with high, measured with a diffusion porometer, on all except the last day. The daily maximum rl (1.5 h after the start of the light period) became greater among low than high rs plants as the difference in rate of leaf extension between the two groups of plants increased with drying soil. Rate of leaf extension was negatively correlated with daily maximum rl and started to decline when relative leaf water content (RLWC), at 5 h after the start of the light period, fell below about 88%. Transpiration rate of plants grown in different soil moisture regimes was correlated (r=+ 0.83, P < 0.01) with mean maximum adaxial leaf conductance (reciprocal of resistance). There was a highly significant correlation (r=+ 0.62, P < 0.01) between calculated adaxial rs and mean minimum measured rl among plants growing at high or intermediate soil moisture, but not at low. Therefore, some random variation in minimum rl, even with adequate moisture, seemed to be unaccounted for by variation in stomatal numbers or size. Selection for increased numbers of adaxial stomata also resulted in more on the abaxial surface, but mean adaxial/abaxial ratio in the ‘frequent’ stomata plants was still only about 9:1. 相似文献
11.
Hayashi N Hayes SG Kaufman MP 《American journal of physiology. Regulatory, integrative and comparative physiology》2001,281(4):R1127-R1133
In thirteen cats anesthetized with alpha-chloralose, we compared the cardiovascular and ventilatory responses to both static contraction and tendon stretch of a hindlimb muscle group, the triceps surae, with those to contraction and stretch of a forelimb muscle group, the triceps brachii. Static contraction and stretch of both muscle groups increased mean arterial pressure and heart rate, and the responses were directly proportional to the developed tension. The cardiovascular increases, however, were significantly greater (P < 0.05) when the triceps brachii muscles were contracted or stretched than when the triceps surae muscles were contracted or stretched, even when the tension developed by either maneuver was corrected for muscle weight. Likewise, the ventilatory increases were greater when the triceps brachii muscles were stretched than when the triceps surae muscles were stretched. Contraction of either muscle group did not increase ventilation. Our results suggest that in the anesthetized cat the cardiovascular responses to both static contraction and tendon stretch are greater when arising from forelimb muscles than from hindlimb muscles. 相似文献
12.
Ikegawa S Funato K Tsunoda N Kanehisa H Fukunaga T Kawakami Y 《Journal of strength and conditioning research / National Strength & Conditioning Association》2008,22(1):128-131
The present study aimed to examine the effect of pennation angle on the force per cross-sectional area for elbow extensor muscles in strength-trained athletes. A total of 52 male bodybuilders (n = 32) and Olympic weightlifters (n = 20) did maximal isometric elbow extension on an isokinetic dynamometer. Muscle cross-sectional area (CSA) and muscle-fiber pennation angle (PA) of the triceps brachii muscles were measured by ultrasonography. Bodybuilders had significantly greater isometric elbow extension force (F), CSA and PA than weightlifters. The ratio of force to CSA (F/CSA) of bodybuilders was significantly lower than that of weightlifters. A significant positive correlation was observed between CSA and PA in both groups (r = 0.832, P < 0.001, and r = 0.682, P < 0.001, for bodybuilders and weightlifters, respectively). The F/CSA was negatively correlated to PA both for bodybuilders (r = -0.408, P < 0.05) and weightlifters (r = -0.465, P < 0.05). Thus present study indicates that the larger pennation angle is associated with the lower force relative to muscle CSA in strength-trained athletes. 相似文献
13.
Julio Benvenutti Bueno de Camargo Felipe A. Brigatto Rafael S. Zaroni Moises D. Germano Darlan Souza Reury F. Bacurau Paulo H. Marchetti Tiago V. Braz Marcelo S. Aoki Charles R. Lopes 《Biology of sport / Institute of Sport》2023,40(1):217
The aim of the present study was to assess the effects of beta-alanine supplementation on muscle strength and thickness. Nineteen resistance-trained men (age: 27.3 ± 5.5 years; height: 178 ± 10 cm; body mass: 83.4 ± 9.7 kg; training experience: 5.9 ± 3.9 years) were allocated to one of the following groups: Beta-alanine (BA) (6.4 g/day of beta-alanine) or Placebo (PLA) (6.4 g/day of maltodextrin). Subjects completed 4 resistance training sessions per week for 8 weeks. The following assessments were performed before and after intervention periods: 1 repetition maximum (1RM) and 60%1RM tests in the bench press (60%1RMBENCH) and back squat (60%1RMSQUAT) exercises; muscle thickness assessment of biceps brachialis (MTBB), triceps brachialis (MTTB), and vastus lateralis (MTVL) by ultrasonography. No significant difference between groups was observed for the absolute increase (pre-post intervention) in the 1RMBENCH (mean difference = 0.8 kg; p = 0.679), 1RMSQUAT (mean difference = 0.1 kg; p = 0.992), MTBB (mean difference = 0.7 mm; p = 0.637), MTTB (mean difference = 1.4 mm; p = 0.282), MTVL (mean difference = 1.6 mm; p = 0.311), 60%1RMBENCH (mean difference = 0.5 repetitions; p = 0.670) and 60%1RMSQUAT (mean difference = 0.7 repetitions; p = 0.690). In conclusion, the 8-week training period induced significant strength and morphological responses. However, the addition of beta-alanine supplementation did not enhance these adaptive outcomes. 相似文献
14.
Sato T Shimizu Y Kano M Suzuki T Kanetaka H Chu LW Côté PD Shimauchi H Ichikawa H 《Cellular and molecular neurobiology》2011,31(1):155-161
The distribution of calcitonin gene-related peptide (CGRP) was examined in skeletal muscles of fore and hind limb as well
as in oral and cranio-facial regions of the degenerating muscle (dmu) mouse, which harbours a null mutation in the voltage-gated sodium channel gene Scn8a. In limb, oral and cranio-facial muscles of wild type mice, only a few motor endplates contained CGRP-immunoreactivity. However,
many CGRP-immunoreactive motor endplates appeared in the triceps brachii muscle, the biceps brachii muscle, the brachialis
muscle, and the gastrocnemius muscle of dmu mice. CGRP-immunoreactive density of motor endplates in the skeletal muscles was also elevated by the mutation. In these
muscles, the atrophy of muscle fibers could be detected and the density of cell nuclei in the musculature increased. In the
flexor digitorum profundus muscle, the flexor digitorum superficialis muscle, and the soleus muscle as well as in oral and
cranio-facial muscles, however, the distribution of CGRP-immunoreactivity was barely affected by the mutation. The morphology
of muscle fibers and the distribution of cell nuclei within them were also similar in wild type and dmu mice. In the lumbar spinal cord of dmu mice, CGRP-immunoreactive density of spinal motoneurons increased. These findings suggest that the atrophic degeneration
in some fore and hind limb muscles of dmu mice may increase CGRP expression in their motoneurons. 相似文献
15.
G. Sjøgaard 《Histochemistry and cell biology》1982,76(4):547-555
Summary The muscles triceps brachii, quadriceps femoris (part vastus lateralis) and soleus were analysed in 6 men and 6 women for fibre composition (% slow twitch, ST-fibres and % fast twitch, FT-fibres), fibre cross sectional areas, and capillarization. Also the fraction of fibres enclosed by their own fibre type was analysed together with the capillary supply of these fibres. Fibre composition was 39(19–60)% ST in m. triceps brachii, 60(29–78)% ST in m. vastus lateralis and 73(49–88)% ST in m. soleus. Fibre areas ranged from 2,320 to 16,667 m2 being smallest in m. triceps brachii and largest in m. soleus (p<0.05) and with ST fibres being significantly smaller than FT fibres in some of the muscles. In all muscles the shape of the fibres was elliptical with the larger diameter being about twice the smaller diameter. Capillary density per cross sectional muscle area was not related to the fibre composition and was 379(302–500) cap/mm2 in m. triceps brachii, 404(284–529) cap/mm2 in m. vastus lateralis and 417(333–592) cap/mm2 in m. soleus. However, capillary supply expressed as fibre type area per capillary was up to 40% larger for FT-fibres than for ST-fibres within the same muscle (p<0.05). The capillary supply of enclosed fibres was not different from that of fibres surrounded also by the other fibre type. The results demonstrate that the difference in capillary supply to ST and FT-fibres is less distinct in humans than in other mammals, which is consistent with the metabolic potentials also being more alike. 相似文献
16.
Pilson Choi Yoshiro Mano Atsuko Ishikawa Masashi Odashima Taishi Umezawa Tatsuhito Fujimura Yoshihito Takahata Takao Komatsuda 《Plant biotechnology reports》2010,4(1):23-27
Quantitative trait loci (QTLs) controlling ability of somatic embryogenesis were identified in soybean. A frame map with 204-point
markers was developed using an RI population consisting of 117 F11 lines derived from a cross between cultivar ‘Keburi’ and a weedy soybean ‘Masshokutou Kou 502’. The parents differed greatly
in their abilities of somatic embryogenesis using immature cotyledons as explants. The ability of somatic embryogenesis was
evaluated in five different experiments: the F11 (evaluated in 1998) and F15 (2002) generations cultured on basal media supplemented with 40 mg l−1 2,4-D (2,4-D1998 and 2,4-D2002), F14 (2001) generation on medium with 40 mg l−1 2,4-D and high sucrose concentration [2,4-D2001 (30 g l−1 sucrose)], and the F11 (1998) and F12 (1999) generations on medium with 10 mg l−1 NAA (NAA1998 and NAA1999). The RILs showed wide and continuous variations in each of the five experiments. In the composite
interval mapping analysis, 2 QTLs were found in group 8 (D1b + W, LOD = 5.42, r
2 = 37.5) in the experiment of 2,4-D1998 and in group 6 (C2, LOD = 6.03, r
2 = 26.0) in the experiment of 2,4-D2001 (high concentration sucrose). In both QTLs, alleles of ‘Masshokutou Kou 502’ with
high ability of somatic embryogenesis contributed to the QTLs. For the other three experiments, no QTL was detected in the
criteria of LOD >3.0, suggesting the presence of minor genes. 相似文献
17.
Antagonistic muscle pairs cannot be fully activated simultaneously, even with maximal effort, under conditions of voluntary co-contraction, and their muscular activity levels are always below those during agonist contraction with maximal voluntary effort (MVE). Whether the muscular activity level during the task has trainability remains unclear. The present study examined this issue by comparing the muscular activity level during maximal voluntary co-contraction for highly experienced bodybuilders, who frequently perform voluntary co-contraction in their training programs, with that for untrained individuals (nonathletes). The electromyograms (EMGs) of biceps brachii and triceps brachii muscles during maximal voluntary co-contraction of elbow flexors and extensors were recorded in 11 male bodybuilders and 10 nonathletes, and normalized to the values obtained during the MVE of agonist contraction for each of the corresponding muscles (% EMGMVE). The involuntary coactivation level in antagonist muscle during the MVE of agonist contraction was also calculated. In both muscles, % EMGMVE values during the co-contraction task for bodybuilders were significantly higher (P<0.01) than those for nonathletes (biceps brachii: 66±14% in bodybuilders vs. 46±13% in nonathletes, triceps brachii: 74±16% vs. 57±9%). There was a significant positive correlation between a length of bodybuilding experience and muscular activity level during the co-contraction task (r = 0.653, P = 0.03). Involuntary antagonist coactivation level during MVE of agonist contraction was not different between the two groups. The current result indicates that long-term participation in voluntary co-contraction training progressively enhances muscular activity during maximal voluntary co-contraction. 相似文献
18.
Stomatal diffusion resistances and leaf growth during droughting of Lolium perenne plants selected for contrasting epidermal ridging 总被引:3,自引:0,他引:3
D. WILSON 《The Annals of applied biology》1975,79(1):83-94
Groups of Lolium perenne plants selected for either deep or shallow adaxial epidermal ridging were grown in a 16 h day of 70 W m-2 at 25°C, and either watered daily to 33% or allowed to dry to and then watered daily to 21% or to 16% soil moisture. During a 9 day experimental period, adaxial leaf resistances (r1) were measured with a diffusion porometer four times daily, transpiration was estimated gravimetrically, and daily rates of leaf extension were recorded. Measurements were also made of minimum abaxial resistances, stomatal frequencies and lengths, and relative leaf water content (RLWC). At 33%, 21% or 16% soil moisture, leaf extension rates of deep ridged leaves were, respectively, slower, the same, and more rapid than those with shallow ridges. At 21% or 16% soil moisture, the adaxial rl of deep-ridged was much lower than that of shallow-ridged leaves at all four sampling times. This difference was most marked on leaves below the youngest fully expanded, and was observed among older leaves even when plants were well watered. At low RLWC (< 85%), leaf resistance was greatest in leaves with shallow ridges. There was no significant difference between the leaf types in the calculated contributions of stomatal frequency or of morphology at any one pore opening, to rl but deep-ridged leaves had more stomataonthe abaxial surface. Daily rate of plant water loss was directly correlated (r=+ 0.86, P < 0.01) with mean daily maximum stomatal conductance (1/rl), and rate of leaf extension negatively with maximum rl. It is suggested that stomata operating in the concavity formed by deep ridges open wider and are less responsive to internal changes in, for example, leaf water status, than those on shallow-ridged leaves because of a more humid microenvironment at the epidermal surface. The results are discussed in relation to the concept of ‘water-savers’ and ‘water-spenders’ and its application to breeding for dry conditions. 相似文献
19.
Helen R. Taylor 《Ecology and evolution》2015,5(15):3140-3150
Genetic marker‐based estimators remain a popular tool for measuring relatedness (rxy) and inbreeding (F) coefficients at both the population and individual level. The performance of these estimators fluctuates with the number and variability of markers available, and the relatedness composition and demographic history of a population. Several methods are available to evaluate the reliability of the estimates of rxy and F, some of which are implemented in the program COANCESTRY. I used the simulation module in COANCESTRY since assess the performance of marker‐based estimators of rxy and F in a species with very low genetic diversity, New Zealand's little spotted kiwi (Apteryx owenii). I also conducted a review of published papers that have used COANCESTRY as its release to assess whether and how the reliability of the estimates of rxy and F produced by genetic markers are being measured and reported in published studies. My simulation results show that even when the correlation between true (simulated) and estimated rxy or F is relatively high (Pearson's r = 0.66–0.72 and 0.81–0.85, respectively) the imprecision of the estimates renders them highly unreliable on an individual basis. The literature review demonstrates that the majority of studies do not report the reliability of marker‐based estimates of rxy and F. There is currently no standard practice for selecting the best estimator for a given data set or reporting an estimator's performance. This could lead to experimental results being interpreted out of context and render the robustness of conclusions based on measures of rxy and F debatable. 相似文献
20.
A Ohtsuka 《The American journal of anatomy》1984,169(3):285-293
Because the architectural and biochemical properties of skeletal muscle dictate its force, velocity, and displacement properties, the major extensors (triceps brachii) and flexors (biceps brachii, brachialis, and brachioradialis) of the elbow in a primate (cynomolgus, monkey) were studied. Functional cross-sectional areas (CSA) were calculated from muscle mass, mean fiber length (normalized to a 2.20 microns sarcomere length), and angle of fiber pinnation measurements from each muscle. Fiber-type distributions were determined and used as a gross index of the biochemical capacities of the muscle. The extensor group had a shorter mean fiber length (31 vs. 47 mm), a larger CSA (13 vs. 8 cm2), and a higher overall percentage of slow-twitch fibers (47 vs. 26%). Consequently, the elbow extensors had a relatively greater potential for force production and force maintenance than the flexors. In contrast, the flexors were designed to optimize their length-velocity potentials; i.e., they had relatively long fibers and a higher fast-twitch fiber composition than the extensors. These morphologic differences between antagonistic muscle groups should be considered when evaluating the motor control mechanisms regulating reciprocal movements about the elbow. 相似文献