Effect of the size of the ligand molecule on the stability of the DNA double helix

The influence of ligand length on helix-coil transition parameters in the presence of different ligand concentrations has been considered theoretically. A decrease of this influence with an increase of ligand length when the binding constant has a constant value was shown. When binding free energy is proportional to the ligand length, i. e. when K = K0m (K-binding constant, m-ligand length) the length effect is unambigous. In the presence of low-ligand concentration the stability of DNA double helix increases with their length, whereas in the presence of high concentrations it decreases.     

A procedure for the determination of spinal cord length in vivo

Using anthropological methods, we measured the body height, length of the spine (ventral and dorsal), leg length, cord length. The data were evaluated statistically and we looked for correlation between leg length and body height, cord length and length of the spine, length of the spine and body height. On the basis of our results, we were able to determine the cord length for clinical use by computing the regression coefficient of leg length and spinal length.     

Centriole size modifications during the cell cycle of the amoebae of the mxyomycete Physarum polycephalum

Anterior and posterior centrioles of Physarum amoebae are indistinguishable by their size during interphase but there is a correlation between the size of the two centrioles in the same amoeba. The interphase length of centrioles in diploid amoebae possessing only one pair of centrioles was 11% longer than in the case of the haploid strain. Treatment with taxol led to a 23 and 32% increase of the mean length in interphase and blocked mitosis, respectively. Conversely, during control mitosis the parental centrioles showed a 12% decrease of their mean length while the size of the daughter centrioles increased progressively. Neither nocodazole nor cold treatment induce a decrease of centriole length. The mean length of the cartwheel structure (internal proximal part) although constant during mitosis could be increased 24% in the presence of taxol. Similarly there was a correlation between the number of anterior satellites and the centriole length.     

Length-tension relationship of the external anal sphincter muscle: implications for the anal canal function

The length at which a muscle operates in vivo (operational length) and the length at which it generates maximal force (optimal length) may be quite different. We studied active and passive length-tension characteristics of external anal sphincter (EAS) in vivo and in vitro to determine the optimal and operational length of rabbit EAS. For the in vitro studies, rings of EAS (n = 4) were prepared and studied in a muscle bath under isometric conditions. For in vivo studies, female rabbits (n = 19) were anesthetized and anal canal pressure was recorded by use of a sleeve sensor placed in the custom-designed catheter holders of 4.5-, 6-, and 9-mm diameters. Measurements were obtained at rest and during EAS electrical stimulation. Sarcomere length of EAS muscle was measured by laser diffraction technique with no probe and three probes in the anal canal. In vitro studies revealed 2,054 mN/cm(2) active tension at optimal length. In vivo studies revealed a probe size-dependent increase in anal canal pressure and tension. Maximal increase in anal canal tension with stimulation was recorded with the 9-mm probe. Increases in anal canal tension with increase in probe size were completely abolished by pancuronium bromide. EAS muscle sarcomere length without and with 9-mm probe in the anal canal were 2.11 +/- 0.08 and 2.99 +/- 0.07 microm, respectively. Optimal sarcomere length, based on the thin filament length measured by thin filament analysis, is 2.44 +/- 0.10 microm. These data show that the operational length of EAS is significantly shorter than its optimal length. Our findings provide insight into EAS function and we propose the possibility of increasing anal canal pressure by surgical manipulation of the EAS sarcomere length.     

Properties of the tendinous structures and series elastic component of EDL muscle-tendon complex of the rat

Characteristics of the entire series elastic component and of tendinous structures separately (tendon and aponeurosis) were compared for rat EDL muscle-tendon complex during isometric contractions, to study the contribution of tendinous structures to series elastic component characteristics. Compliance of series elastic component was measured using quick length decreases during the force plateau of isometric contractions. Lengths of tendinous structures were measured using macro-photographs during passive and active muscle conditions. Length data obtained from aponeurosis showed inconsistency with respect to elastic behaviour in two ways: the difference of aponeurosis length in active muscle at short length and at optimum length exceeded the extension of series elastic component for the same force range. Furthermore, aponeurosis in passive muscle at optimum length was considerably longer than in active muscle at short length, despite the fact that muscle force in the former condition is smaller than in the latter. It is concluded that aponeurosis length does not depend exclusively on force but is also muscle length-dependent. This muscle length dependence was not found for tendon of EDL. Additional experiments showed that series elastic component compliance does not depend on muscle length. It is concluded that muscle length-dependent changes of aponeurosis length-force characteristics involve shifts of its force length curve to other aponeurosis lengths.     

Molecular dynamics simulations to determine the optimal loop length in the helix-loop-helix motif

In this study, 100 ps molecular dynamics simulations were conducted to determine the optimal length of the Gly loop in the helix-loop-helix motif. The results revealed that the length of the loop significantly affected the stability of the two alpha-helices. In addition, the optimal loop length to maintain the highest helicity of the target peptide was found to be the one corresponding to 7 Gly residues. Longer loop length resulted in structural destabilization due to the entropic effect, while shorter loop length was not suitable to achieve intrachain packing of the two alpha-helices.     

林麝幼体消化系统解剖研究

测定了不同日龄幼麝的消化道长度、胃的周长。其结果为:十二指肠1日龄时长度为19.7cm,57日龄时为36.1cm,是出生时的1.8倍;回肠1日龄时长度为90.5cm,57日龄时为206.1cm,为出生时的2.3倍;盲肠1日龄时长度为4.2cm,57日龄时为9.4cm,为出生时的2.2倍;直肠1日龄时长度为9.0cm,57日龄时为37.2cm,为出生时的4.1倍。18日龄时,瘤胃的周长大于皱胃。     

The helical content of the YscP molecular ruler determines the length of the Yersinia injectisome

The length of the Yersinia injectisome needle is determined by the protein YscP, which could act as a molecular ruler. The analysis of the correlation between the size of YscP and the needle length in seven wild-type strains of Yersinia enterocolitica reinforced this hypothesis but hinted that the secondary structure of YscP might influence needle length. Hence, 11 variants of YscP₅₁₅ were generated by multiple Pro or Gly substitutions. The needle length changed in inverse function of the helical content, indicating that not only the number of residues but also their structure controls length. Taking the secondary motifs into account, Pro/Gly-variants were subjected to in silico modelling to simulate the extension of YscP upon needle growth. The calculated lengths when the helical content is preserved correlated strikingly with the measured needle length, with a constant difference of ∼29 nm, which corresponds approximately to the size of the basal body. These data support the ruler model and show that the functional ruler has a helical structure.     

Variability of tail length in hybrids of the Japanese macaque (Macaca fuscata) and the Taiwanese macaque (Macaca cyclopis)

In primates, tail length is subject to wide variation, and the tail may even be absent. Tail length varies greatly between each species group of the genus Macaca, which is explained by climatic factors and/or phylogeographic history. Here, tail length variability was studied in hybrids of the Japanese (M. fuscata) and Taiwanese (Macaca cyclopis) macaque, with various degrees of hybridization being evaluated through autosomal allele typing. Relative tail length (percent of crown–rump length) correlated well with the number of caudal vertebrae. Length profiles of caudal vertebrae of hybrids and parent species revealed a common pattern: the length of several proximal-most vertebrae do not differ greatly; then from the third or fourth vertebra, the length rapidly increases and peaks at around the fifth to seventh vertebra; then the length plateaus for several vertebrae and finally shows a gentle decrease. As the number of caudal vertebrae and relative tail length increase, peak vertebral length and lengths of proximal vertebrae also increase, except that of the first vertebra, which only shows a slight increase. Peak vertebral length and the number of caudal vertebrae explained 92?% of the variance in the relative tail length of hybrids. Relative tail length correlated considerably well with the degree of hybridization, with no significant deviation from the regression line being observed. Thus, neither significant heterosis nor hybrid depression occurred.     

Evaluation of various methods of measurement of the microtubule length in the cytoplasm of cultured cells

It is generally assumed that microtubules in tissue culture cells extend from the centrosome to cell periphery, and the length of individual microtubules averages several dozens of microns. However, direct electron-microscopic measurements have cast some doubt on this assumption. In this study, the average length of microtubules in cultured Vero cells was estimated using a combined approach. The length of free cytoplasmic and centrosomal microtubules was determined by means of electron microscopy in serial sections; concurrently, the length of free microtubules in the lamella was measured in preparations stained with tubulin antibodies (an indirect immunofluorescent method), by tracing saltatory particle movements along the microtubules in living cells. According to the data of immunofluorescent microscopy, microtubule length in the lamella averaged 4.57 +/- 3.69 microns. However, since two or more microtubules can overlap, their length may be slightly overestimated by this method. On the other hand, saltatory movements are easy to monitor and measure fairly accurately, but their range may be shorter than the actual microtubule length because of a limited processiveness of motors (kinesin and dynein). On average, the trajectories of saltatory movements in living cells were 3.85 +/- 0.72 microns long. At the electron-microscopic level, microtubule length was analyzed using pseudo-three-dimensional reconstructions of the microtubule systems around the centrosome and in the lamella. The length of free microtubules in the lamella reached 18 microns, averaging 3.33 +/- 2.43 microns; the average length of centrosomal microtubules was 1.49 +/- 0.82 microns. Good correspondence between the data on microtubule length and arrangement obtained by different methods allows the conclusion that most of free microtubules in Vero cells actually have a length of 2-5 microns; i.e., they are much shorter than the cell radius (about 25 microns). Microtubules extending from the centrosome are shorter still and do not reach the cell periphery. Thus, most microtubules in the lamella of Vero cells are free and their ordered arrangement is not associated with their attachment to the centrosome.     

Sperm length evolution in the fungus-growing ants

Eusocial insects offer special opportunities for the comparativestudy of sperm traits because sperm competition is absent (inspecies with obligatory monandry) or constrained (in lineageswhere queens mate multiply but never remate later in life).We measured sperm length in 19 species of fungus-growing ants,representing 9 of the 12 recognized genera, and mapped theseonto the ant phylogeny. We show that average sperm length acrossspecies is highly variable and decreases with mature colonysize in basal genera with singly mated queens, suggesting thatsperm production or storage constraints affect the evolutionof sperm length. Sperm length does not decrease further in multiplymating leaf-cutting ants, despite substantial further increasesin colony size. In a combined analysis, sexual dimorphism explained63.1% of the variance in sperm length between species. As colonysize was not a significant predictor in this analysis, we concludethat sperm production trade-offs in males have been the majorselective force affecting sperm length across the fungus-growingants, rather than storage constraints in females. The relationshipbetween sperm length and sexual dimorphism remained robust inphylogenetically independent contrasts. Some of the remainingvariation was explained by the relative size of the sperm-storageorgan, but only in the multiply mating leaf-cutting ants, suggestingthat sperm-storage constraints become important for the evolutionof sperm length in this derived group. Mate number affectedsperm length to a minor extent, and only in interaction withother predictor variables, suggesting that sperm competitionhas not been a major selective force for sperm length evolutionin these ants.     

Plant resistance, plant traits, and host plant choice of the leaf-folding sawfly on the arroyo willow

Abstract. 1. The hypotheses that genetic variation in host plant resistance of the arroyo willow affected leaf folder ( Phyllocolpa sp.) (Hymenoptera: Tenthredinidae) density and that genetic variation in shoot length and leaf length was correlated with resistance were tested.
2. Willows grown in pots and exposed to ovipojsition by the leaf folding sawfly in cages had significantly different densities among clones, indicating variation in resistance caused by genetic differences among conspecific host plants.
3. There was a general correspondence between leaf folder density on potted cuttings and on the plants in the field that were the sources of cuttings.
4. In behavioural choice experiments, susceptible clones (with highest leaf fold densities) had the highest oviposition activity of female leaf folders compared to clones that were resistant to the leaf folder.
5. Clones differed significantly in shoot length and leaf length among clones grown in pots, among clones in the field, and between shoots with galls and shoots without galls on clones in the field.
6. Leaf folder density was significantly positively correlated with mean shoot length on field clones in 1985 and 1986, but was not correlated with leaf length, although leaf length and shoot length were correlated.
7. Leaf length variation among willow clones accounted for a significant portion of the variation in resistance of potted willows, but shoot length was unimportant.     

Intestine length in the fishes of a tropical stream: 1. Ontogenetic allometry

Synopsis We examined the ontogenetic allometry of intestine length in relation to body length and body mass in 21 species of fish from forest streams in Panama. The relationships between log₁₀ intestine length and log₁₀ body length and mass were well described by linear regressions, although some species showed slight curvilinearity. Slopes and intercepts of the linear regressions varied considerably among species. Intestine length was positively allometric in most species, with slopes of the intestine length:body length relationship ranging from 1.09 to 2.11. Relative intestine lengths (intestine length/body length) varied by two orders of magnitude (0.39–38.44) in the data set as a whole, but the variation was about one order of magnitude when species were compared at a common body size. Species in which body mass increased more rapidly with body length had more rapid increases in intestine length with body length. Among omnivorous and carnivorous species compared at the same body length, heavier species had longer intestines. Interspecific comparisons of relative intestine length may produce misleading conclusions unless comparisons are made at a common size and account for differences in relative mass.     

Some observations on the growth and length: weight relationship of the South Georgia cod Notothenia rossii marmorata Fischer during the first four years of life

The paper describes the length: weight relationship and the results of back-calculating fish length from scale length for Notothenia rossii marmorata Fischer, collected in April 1961 from Leith Harbour, South Georgia.     

Molecular analysis of the heterogeneity region of the human ribosomal spacer

The human ribosomal non-transcribed spacers are 30 X 10(3) base-pairs (or 30 kb) in length with a limited length heterogeneity localized in a specific region downstream from the 3' end of the transcribed region. Total DNA digested with EcoRI and BamHI and hybridized with a probe containing the 3' end of the 28 S ribosomal RNA coding region shows four major bands of 3.9 kb, 4.6 kb, 5.4 kb and 6.2 kb. The 5.4 kb band is the most abundant in every individual, followed by the 4.6 kb band. The longest and the shortest size classes are less well-represented and may even be absent. Every individual shows his own pattern of relative abundance of non-transcribed spacer length classes that can be followed through generations. We decided to investigate the molecular structure of the heterogeneity region, in order to cast light onto the mechanisms underlying the origin and maintenance of this length heterogeneity. Pertinent spacer regions of eight ribosomal clones from two human genomic libraries were subcloned and analyzed by restriction mapping and nucleotide sequencing. In the minimal length class, there is a sequence of 700 base-pairs that appears to be tandemly duplicated once, twice or three times in the other length classes. This repeated DNA module contains a region consisting of repetitions of simple pyrimidine groups like C-T, C-T-T-T or C-C-C-T. DNA module repeats may differ by the length of this pyrimidine-rich region. However, these length variations are not continuous, as revealed by Southern transfer analysis of several individuals and different cloned gene units: instead, the repeated modules fall into two discrete length classes of about 700 base-pairs and 800 base-pairs. An imperfect duplication of a short sequence of 86/89 base-pairs is present at the boundary between the heterogeneity region and the upstream flanking region, representing a very ancient duplication event.     

Sperm morphometry in the Atlantic salmon

This study sampled sperm from wild Atlantic salmon to explore relationships between sperm form and function. Detailed measurements of sperm morphometry (head, flagellum and total length) and sperm activity (longevity and % motility) were made from 24 reproductively active males (13 anadromous and 11 mature parr) on two occasions post-stripping. There was significant between-male variance in total sperm length but this variance was not related to body size. Despite this variance in sperm length, no relationships were found between a male's sperm activity (longevity or % motility) and his sperm length. There were also no relationships between sperm head length and flagellar length, and no evidence for a trade-off between sperm length and numbers. It is suggested that the significant between-male variance in sperm morphometry supports diploid control of spermatogenesis: haploid expression of sperm phenotype would be manifested as profound variance within (and not between) each male's spermatozoal characteristics.     

Increase in the pace of the growth of the human fetus towards the end of pregnancy]

Growth velocity curves of 19 biometrical parameters were established from 490 normal fetuses or neonates, who died in the perinatal period, and from 4,507 ultrasound examinations. There was a velocity fall for numerous parameters during the third trimester of gestation, but growth rate started up again after 38 weeks for some of them (femur length, biparietal diameter, crown-rump length, head circumference ...). No acceleration was found for body weight and crown-heel length by the end of gestation.     

The urogenital papilla in the Holarctic lamprey (Petromyzontidae)

Synopsis The urogenital papillae of 30 species of Holarctic lampreys were examined to determine if this structure has any taxonornic use. Total length, branchial length and papilla length were measured. A correlation between mean papilla length and mean total length of the species existed in males for parasitic species but not nonparasitic species, indicating a potential use in nonparasitic species. In nonparasitic species the most obvious differences existed in the papilla length: branchial length ratio. From the limited material available there appeared to be no geographic variation in this ratio, although there is a seasonal variation with the ratio increasing as, spawning approaches. It therefore appears that urogenital papilla length has taxonomic value in male nonparasitic lampreys, provided the specimens are collected in spawning condition. The female papilla is too small to be of use.     

Variations in the Size of Mitotic Cells in the Root Meristem

Variations in the length of mitotic and interphase cells were analyzed in various tissues of wheat roots and in the cortex of maize roots. Reliable differences were shown in the length of mitotic cells in individual file clones of cells of the same tissue. The mean lengths of dividing cells in different roots differed to a lesser extent than those of different files in the same tissue of one root. Within the file, the length of the sister simultaneously dividing cells differed the least, while the difference of lengths of the neighbor simultaneously dividing nonsister cells was bigger. The mean length of interphase cells in any file was always less than that of mitotic cells by a factor of 1.45. This ratio was almost invariable for files and tissues in both the plants we studied and corresponded to that of an exponentially growing cell population. In addition, a very small number of cells were found (less than 1%) in meristems, which are longer than the mitotic cells. The length of these cells exceeded those of mitotic cells by less than twice. The origin of such cells is discussed. The length of mitotic cells near the quiescent center is more variable than in the middle of the meristem in the cortex of both plants. In the meristem basal part, the mitotic cells were no longer than those in the middle of the meristem but there were no small dividing cells. In the wheat epidermis, the cells are differentiated into trichoblasts and atrichoblasts and, therefore, the length of the dividing cells is highly variable. The cell length is essential for their transition to mitosis for all studied proliferating meristem cells.     

Functional morphology of the M. gastrocnemius medialis of the rat during growth

Length-force relations, both active and passive, and twitch contraction characteristics were quantified for left medial gastrocnemius muscles of four young, four adult, and four old male Wistar rats. Muscle and bundle optimum length and muscle weight were also determined and subsequently used for calculation of a number of morphological characteristics of the muscles. Fiber optimum length was derived from muscle bundle optimum length. Generally, physiological characteristics remained constant during growth. There was no change either in active tension at muscle optimum length or in active working range relative to fiber optimum length, relative passive fiber stiffness, active force relative to passive force at optimum length, twitch contraction time and twitch half relaxation time at optimum length. A number of morphological changes, however, did take place in the medial gastrocnemius muscle during growth. Fiber optimum length increased but only by about 2 mm from youth to old age, whereas muscle optimum length increased by approximately 14 mm, presumably owing to extensive hypertrophy of the muscle fibers during growth. The priority for force of the medial gastrocnemius muscle (defined as the quotient of physiological cross-sectional area of a muscle and the cubed root of its volume, a measure independent of architecture and dimensions of muscles) increased during growth. This increase indicates that during growth the muscle shifts relatively more towards force generation than towards excursion generation. These findings are discussed in view of existing scaling theories.