MITOTIC ACTIVITY IN THE CAMBIAL ZONE OF PINUS STROBUS

Mitotic activity in the cambial zone of 20-year-old Pinus strobus L. trees was determined quantitatively, using mitotic counts from serial tangential sections of sample pieces. Counts from nine cores 1.6 mm in diameter from each sample piece were averaged and expressed as the number of mitoses per core with the sampling error. Estimation of the number of cambial zone cells per core permitted calculation of mitotic indices. In the fourth internode from the ground the first mitoses were observed on April 15 and the last on September 15. The number of mitoses per sample piece was comparable throughout each internode at any one sampling, but the number was higher in internodes within the crown than in those below it. Mitotic index was not appreciably higher within the crown, but it decreased from 3.7 in spring to 2.0 in fall. An internode in the crown sampled May 11–13 showed afternoon peaks in mitotic activity, but an internode below the crown showed no peaks, nor did other internodes sampled later in the season.     

Vertical and radial profiles in tracheid characteristics along the trunk of Douglas-fir trees with implications for water transport

The main stems of three young Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirbel) Franco) trees were dissected to obtain samples of secondary xylem from internodes axially along the trunk and radially within each internode. From these samples, measurements were obtained of tracheid diameter, length, the number of inter-tracheid pits per tracheid, and the diameter of the pit membranes. In addition, samples were obtained along the trunks of three old growth trees and also a small sample of roots for measurement of tracheid diameter. A gradient was apparent in all measured anatomical characters vertically along a sequence among the outer growth rings. These gradients arose not because of a gradient vertically along the internodes, but because of the strong gradients present at each internode among growth rings out from the pith. Tracheid characteristics were correlated: wider and longer tracheids had more numerous pits and wider pits, such that total pit area was about 6% of tracheid wall area independent of tracheid size. A stem model combining growth rings in parallel and internodes in series allowed for estimates of whole trunk conductance as a function of tree age. Conductance of the stem (xylem area specific conductivity) declined during the early growth of the trees, but appeared to approach a stable value as the trees aged.     

Morphological and histological differences in the development of dwarf mutants of sexual and somatic origin in diverse woody taxa

Morphological and histological observations were made on eight dwarf mutants arising either as seedlings from sexual reproduction or from somatic bud mutations (witches'-brooms in the crowns of normal trees). The most predominate morphological trait contributing to the expression of dwarfism in all taxa was the reduction of final internode lengths along the shoot axis. In taxa of sexual origin, with the exception of Prunus, there was a consistent reduction in the number of preformed leaves contained in the winter buds. In addition, in two taxa (Liquidambar and Tsuga) there was an almost complete absence of neoformed leaves and sylleptic branches on current year shoots. Conversely, in mutants of somatic origin there was no apparent reduction in the number of preformed leaves. Genetic dwarfness in this group resulted solely from decreases in final internode length. Significant differences in the cellular basis of dwarfism between mutants of different genetic origins are clearly evident. In dwarf trees arising from sexual reproduction, reduction in final internode length is attributed predominately to inhibition of mitotic activity in developing internodes resulting in highly significant decreases in final cell number, and not cell length. In mutants of somatic origin, the reduction in length of mature internodes results from a decrease in final cell length, rather than a decrease in cell number. Physiological mechanisms associated with the genetic expression of these morphogenetic differences are suggested.     

CAMBIAL ACTIVITY IN ALASKAN WHITE SPRUCE

Cambial activity in white spruce stems in Alaska was observed during a 2-year period in 50–60-year-old natural stands. Mitotic index was used as a measure of the rate of periclinal division of fusiform cells in the cambial zone. Anticlinal divisions were relatively rare, averaging only one per 27S periclinal divisions in most stems. Mitotic index, at any given time, appeared uniform throughout the cambial zone of an internode, among internodes of the same tree, and even among trees growing at markedly different rates. Diurnal variation in mitotic index was observed. There were three distinct growing season periods: early, grand, and late. Early period activity was characterized by reactivation of periclinal division, erratic mitotic indices, and an approximate doubling of the number of cambial zone cells per radial file (NCZ). Production of the first new xylem and phloem elements marked the beginning of the grand period. Rate of cell production in the cambial zone remained about equal to derivative production for the next 45–50 days, when about 80 % of annual xylem and phloem increment occurred. There was a drop in NCZ at the beginning of the late period coincident with a decline in mitotic index, and NCZ soon dropped to the dormant level. Complete termination of cambial activity was gradual, extending through late August and perhaps into September.     

Comparison of lymphocyte production in lymphoid organs and their compartments using the metaphase-arrest technique

Summary Lymphocyte proliferation was studied in normal young anesthetized pigs by the metaphase-arrest technique using vincristine (VCR). In each animal biopsies were taken simultaneously from the thymus, mesenteric lymph nodes, spleen, palatine tonsil and Peyer's patches from the ileum and jejunum. After taking the first samples, 0.25 mg VCR/ kg body weight was injected i.v. and then four more biopsies were excised for up to 3.5 h after VCR. Imprints of the lymphoid organs were evaluated as an overall index for each organ, and histological sections were used to determine the mitotic index in typical B-and T-lymphocyte areas in these organs. In follicles of mesenteric lymph nodes, tonsils and the two types of Peyer's patches a comparable increase in the mitotic index was found, 3.62% per hour. In the corona the increase was also comparable but much lower, 0.43% per hour and in the interfollicular area similarly 0.38% per hour. In the spleen the mitotic rate was 0.69% for the white pulp and 0.42% per hour for the red pulp. In the thymic cortex the mitotic index increased by 0.49% and in the medulla by a surprisingly high value of 0.32% per hour. The metaphase-arrest technique in larger animals enables a comparison of lymphocyte production among organs and their different compartments, and demonstrates the important contribution of peripheral lymphoid organs to the renewal of the lymphocyte pools.List of Abbreviations DNA deoxyribonucleic acid - ¹⁴ C-TdR thymidine labelled with ¹⁴C - ³ H-TdR tritiated thymidine - r _m rate of entry of cells in mitosis per hour - VCR vincristine sulphate Partly presented at the XII Int. Anat. Congress in London, August 1985     

红松人工林优势木竞争指数影响因子

在温带湿润气候区东段不同立地条件下的红松人工林内设置面积为600 m~2(20 m×30 m)的70块矩形固定样地。在每个样地内,选取5颗最高且长势较好的优势木作为研究的对象木,用Voronoi图确定优势木相应的竞争木,测定每一块样地内优势木与竞争木之间的距离。采用Hegyi单木竞争指数模型,分析优势木在不同样地水平上的种内竞争强度,探讨林分生长因子、地形因子、土壤养分因子对优势木竞争指数的影响,并对这3类因子与优势木竞争指数进行相应的拟合和相关性分析。结果表明：红松人工林优势木竞争强度随着优势木胸径的增大而变小,并且两者之间的关系服从幂函数;红松优势木的竞争指数与其树高、胸径、冠幅呈极显著的相关关系(P<0.01);坡向、坡位、海拔对竞争指数影响极显著(P<0.01);红松人工林优势木竞争指数的大小与土壤氮磷钾含量均呈极显著的相关关系(P<0.01);pH值对优势木竞争指数的影响不显著。当红松人工林优势木平均胸径达到45cm,优势木平均树高和冠幅大于周围竞争木时,其对周围资源的利用程度增大,林木会发生自然稀疏现象,其所受的竞争压力减小。红松喜光性强,对水分的要求高,...     

The ecological distribution of mycorrhizas of Pinus uliginosa

On the site where the ground water table was during the year at the depth of 15 cm, I found on average 1,238 short mycorrhizal roots from 500 of soil samples, each of 500 g, about 70 % fragments were from living roots. There were four sub-subtypes: Aa, Ac, Bd and Cf and three subtypes of ecotrophic mycorrhizas: A, B and C. About 70.3 % was A subtype, 17.6 % of C and 7.1 % of B subtype.On the other stand where the ground water table was at 50 cm, there was a rich mycorrhizal spectrum. In the soil samples were on average 2,769 short mycorrhizal roots per sample; about 85 % were from living roots. I described there 11 mycorrhizal sub-subtypes: Aa, Ac, Ba, Bd, Ca, Cd, Cf, Fd, Fg, Ga and Ia. In samples were 65 % of A subtype, 3.2 % of B subtype, 9.8 % of C subtype, 4.2 % of F subtype, 15.0 % G subtype (Cenococcum graniforme) and 2.7 % of I subtype.No significant differences were found in the mycorrhizal subtype variety between young seedlings and older trees. The richest mycorrhizal association were found down to depth 10 to 15 cm. There were approximately 253 kg/ha of mycorrhizal fragments in the first stand and 464 kg/ha of mycorrhizas in the 15 cm surface soil layer in the sedond stand.     

A computer simulation study on the number of loci and trees required to estimate genetic variability in cacao (Theobroma cacao L.)

Current methods for measures of genetic diversity of populations and germplasm collections are often based on statistics calculated from molecular markers. The objective of this study was to investigate the precision and accuracy of the most common estimators of genetic variability and population structure, as calculated from simple sequence repeat (SSR) marker data from cacao (Theobroma cacao L.). Computer simulated genomes of replicate populations were generated from initial allele frequencies estimated using SSR data from cacao accessions in a collection. The simulated genomes consisted of ten linkage groups of 100 cM in length each. Heterozygosity, gene diversity and the F statistics were studied as a function of number of loci and trees sampled. The results showed that relatively small random samples of trees were needed to achieve consistency in the observed estimations. In contrast, very large random samples of loci per linkage group were required to enable reliable inferences on the whole genome. Precision of estimates was increased by more than 50% with an increase in sample size from one to five loci per linkage group or 50 per genome, and up to 70% with ten loci per linkage group, or equivalently, 100 loci per genome. The use of fewer, highly polymorphic loci to analyze genetic variability led to estimates with substantially smaller variance but with an upward bias. Nevertheless, the relative differences of estimates among populations were generally consistent for the different levels of polymorphism considered.     

Analysis of DNA size,content and cell cycle in leaves of Napier grass (Pennisetum purpureum Schum.)

Summary Mesophyll cell nuclei isolated from leaves of Pennisetum purpureum were analysed by flow cytometry to determine the nuclear DNA content and the percentage of cells in different phases of the cell cycle. Samples taken from base, middle and tip regions of leaves 2 to 8 (leaf 1, which was adjacent to the meristem, was too small to sample) showed no significant differences in the amount of DNA per G₁ nucleus due to either age or position. The average amount of DNA per G₁ nucleus was 5.78 pg. Although the majority of cells for each sample were in G₁, samples taken from older leaves had higher percentages of cells in G₂ and S phases. More specifically, base and middle regions of older leaves had a higher percentage of cells in G₂ than all three positions in younger leaves. Electrophoretic analysis of nuclear DNA from leaves 2 to 7 showed no evidence of degradation or difference in fragment size for any sample or position. This study was compared to previous work on the relationship between leaf age and embryogenic competence in Pennisetum purpureum. The results suggest that changes in the cell cycle, and/or a loss or fragmentation of the nuclear DNA, are not responsible for loss of embryogenic competence in mature leaf tissue.     

SPATIAL AND TEMPORAL VARIATION IN GROUP RELATEDNESS: EVIDENCE FROM THE IMPORTED WILLOW LEAF BEETLE

The distribution of genetic variance within and among socially interacting groups, often quantified as the average relatedness or r?, is an important determinant of the evolution of social behaviors. Models of social evolution often treat this average as a constant characteristic of a species. In this paper, we present data documenting the degree of temporal and spatial variation in the average relatedness of larval groups of imported willow leaf beetles, a species whose immatures display several primitive social behaviors. Collections of groups were made over three generations at three localities in Virginia and three localities in Illinois. Average relatedness was estimated from the distribution of electrophoretically determined genotypic frequencies within and among groups for each collection. Average relatedness ranged from 0.20 at one locality in Illinois to 0.65 at one locality in Virginia. Individual cases of pairwise differences between samples indicated that there were both temporal and locality effects. Further, statistical analysis showed the set of relatedness values to be heterogeneous with significant locality effects. Geographic genetic variance was also partitioned among trees sampled within localities in Illinois, among localities within each state, and between states. Notably, significant gene-frequency variation among groups of beetles occupying closely spaced trees was detected at several localities.     

Mitotic and Labelling Activity In Normal Human Epidermis In Vivo

Labelling and mitotic indices were studied in the epidermis of twenty-eight young men. A mean labelling index of 5.5% was found from the whole study and a mean mitotic index of 0.06%. Mitotic index particularly was extremely variable; indices between 0.002 and 0.438% were found in individual biopsies. In the first two of three experiments in which mitotic index at 09.00 hours was compared with that at 15.00 hours, significant differences were found (15.00 hours > 09.00 hours by a factor of 2.6, P < 0.001). However, in the third such experiment no such difference was found, suggesting that the timing and occurrence of diurnal rhythms of mitotic activity may not be consistent in normal human epidermis. In the one experiment in which it was investigated, a significantly higher mitotic index was found at 21.00 hours compared to 09.00 and 15.00 hours. Labelling index did not vary significantly at 09.00, 15.00 or 21.00 hours. However, labelling index did show a significant pattern of change over a 12-month period in two groups of subjects; peaks of labelling were seen in July and troughs in January. Very high ratios of labelled: mitotic cells were found, the median ratio for the whole study being ninety-eight labelled: one mitotic cell. This finding supports the possibility that not all labelled cells subsequently go on to divide in normal human epidermis.     

Variability of the Cytological Parameters of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L. Seeds from the Unique Hrenovskoy Pine Forest

Hrenovskoy pine forest is a unique island stand at the boundary of the species range of Scots pine Pinus sylvestris L. This object is of exceptional economic value, because it serves as a forest-seed base for the Voronezh oblast and some other regions of Russia; therefore, the stand and seed qualities have to be monitored constantly. The results of the first cytogenetic study of the seed progeny of P. sylvestris from the Morozov Grove, a high-quality stand in a reserved site within the Hrenovskoy pine forest, are reported. The studies have been performed in order to obtain a more correct assessment of seed quality based not only on their germination and energy of germination (traditionally used by forest breeders), but also on their genomic stability. The latter may be estimated by the stability of chromosome number in the somatic cells of seedlings and the regularity of mitotic divisions, because they also characterize the state of the generative system of parental forms and may serve as an integrated estimate of the stand development homeostasis. Therefore, the chromosome number, mitotic and nucleolar activities, and the number and spectrum of pathological mitoses (PMs) have been determined. Seedlings have been obtained from 240 seeds (collected from 12 trees) that resulted from free pollination. The cytological analysis of the rootlets of these seedlings has not detected any deviations from the chromosome number typical of the species P. sylvestris L. (2n = 24). However, considerable variation has been found in each family with respect to the mitotic index (MI) (from 4.2 ± 0.36 to 8.1 ± 0.39%) and the number of PMs (from 0.5 to 2.1%); micronuclei have also been found in each family (from 0.01 to 0.05%). In general, the phenotypic characteristics and the variation pattern of cytological parameters of the progeny of the trees studied in the Hrenovskoy pine forest, together with the high germination rate of seeds (90–98%), indicate that the current state of pines in the Hrenovskoy pine forest can be considered to be satisfactory. However, the presence of micronuclei in all variants and the decrease in MI in some individual plants (which was, on average, 6.1 ± 0.03% in the sample studied, i.e., significantly lower than that of P. sylvestris from the Usmanskii pine forest (7.3 ± 1.2%), where the conditions are optimal for this species) may serve as the bioindicators of the deterioration of both the state of trees themselves and the ecological conditions in the Hrenovskoy pine forest. Therefore, the population structure of this valuable autochtonic stand should be reproduced urgently.__________Translated from Genetika, Vol. 41, No. 6, 2005, pp. 778–783.Original Russian Text Copyright © 2005 by Butorina, Cherkashina, Chernodubov, Avdeeva.     

Effects of heavy metal pollution on genetic variation and cytological disturbances in thePinus sylvestris L. population

This isoenzymatic and cytogenetic study has shown significant differences in genetic composition between two groups of Pinus sylvestris trees: tolerant and sensitive to heavy metal pollution. Total and mean numbers of alleles and genotypes per locus were higher in the pollution-sensitive group of trees, but heterozygosity (Ho) was lower in this group. Fixation index (F) indicates that trees tolerant for pollution were in the Hardy-Weinberg equilibrium, while the sensitive group had a significant excess of homozygosity. Cytological analyses demonstrated numerous aberrations of chromosomes in meristematic root tissue of seedlings developed from seeds collected from trees in the polluted area. The aberrations included chromosome bridges and stickiness, laggards, retarded and forward chromosomes, and their fragments. The mitotic index was markedly lower in this group of seedlings, as compared to the control. Both isoenzymatic and cytological analyses showed a significant influence of heavy metal ions on the genetic structure of the Pinus sylvestris population.     

POLAR TRANSPORT OF GROWTH-REGULATORS IN PITH AND VASCULAR TISSUES OF COLEUS STEMS

Movement of IAA-C¹⁴ and 2,4-D-C¹⁴ through cylinders of known size and histology was compared using liquid scintillation counting. Both auxins showed strongly polar movement, even through pith parenchyma cut from Coleus internode #5, the youngest internode to have ceased elongation. The polar movement was correlated with sizable elongation of the excised cylinders. Velocities of basipetal movement for a given auxin, as determined by the intercept method, showed small or negligible differences between pith and “corner” cylinders. (Corner cylinders comprised mostly vascular tissue, plus some cortical, pith, and epidermal cells.) For IAA, basipetal velocities ranged from 2.1 to 3.3 mm per hr; for 2,4-D, they were 0.6–0.8. For both auxins there was much more net loss into corner than into pith cylinders, a difference associated with the fact that corner cylinders showed 10 times as many cells in transection. More 2,4-D moved basipetally through corner than through pith cylinders and the reverse was true of IAA. By chromatographic evidence, all the radioactivity in the basal receiving blocks was still associated with the auxin molecules.     

The population kinetics of human male germ cells in the antenatal period of ontogeny]

Time course of development of male germ cells in man during prenatal development was studied quantitatively for the first time. For each period of the prenatal development the following characteristics were determined: relationship between the number of germ and somatic cells in spermatic cords, mitotic index for germ cells the intensity of their degeneration, average diameter of their nuclei, and the proportion of germ cells at the stage of preleptothene.     

Molecular-marker analysis of quantitative traits for growth and development in juvenile apple trees

Random amplified polymorphic DNAs (RAPDs) were used in combination with a double pseudo-testcross mapping strategy to estimate the position and effects of quantitative trait loci (QTLs) for traits influencing juvenile tree growth and development in two apple cultivars. The mapping population consisted of 172 F₁ trees from a cross between the columnar mutant ‘Wijcik McIntosh’ and a standard form disease-resistant selection NY 75441-58. Significant associations were found between markers and height increment, internode number, internode length, base diameter increment, base diameter after 9 years of growth, branch number, and leaf break. The number of genomic regions associated with each trait varied from one to eight. The amount of variation explained by linear regression on individual marker loci (R²) ranged from 3.9 to 24.3%, with an average of 7%. Multiple regression using markers for each putative QTL explained from 6.6 to 41.6% of the phenotypic variation, with an average value of 24.3%. A large number of traits had significant variation associated with the map position of the dominant columnar gene, Co. QTL stability over years was estimated by comparing the locations of putative QTLs for traits measured in multiple years. The majority of genomic regions were associated with a trait in only a single year, although regions associated with a trait in more than 1 year were also detected. The limitations of dominant markers and an outbred mapping pedigree for QTL analysis are discussed. Received: 27 August 1997 / Accepted: 10 February 1998     

Attacks on living spruce trees by the bark beetle Ips typographus (Col. Scolytidae) following a storm-felling: a comparison between stands with and without removal of wind-felled trees

Abstract 1 To maintain biodiversity in forests more wind‐felled trees must be left where they fall. However, there is concern among forest owners that this may result in higher tree mortality caused by the spruce bark beetle, Ips typographus (L.) (Col.: Scolytidae). 2 In the 5 years following a major storm disturbance the number of standing spruces killed by I. typographus was determined in a total of 53 stands. In five of the stands all wind‐thrown trees were left (unmanaged stands) and in 48 of the stands, which were situated at distances of 1.4–10.0 km from each focal unmanaged stand, the wind‐felled trees were removed directly after the storm (managed stands). In the winter preceding the fifth summer new storm‐fellings occurred in the study area. 3 In the 4‐year period between the first and second storm‐fellings, 50–322 standing trees were killed by I. typographus per unmanaged stand. There was a direct linear relationship between the number of storm‐felled spruces colonized by I. typographus and the number of trees subsequently killed in the unmanaged stands. 4 Tree mortality caused by I. typographus in the unmanaged stands was almost nil in the first year, peaked in the second or third year, and decreased markedly to a low level in the fourth and fifth years. 5 In the 4‐year period between the first and second storm‐fellings twice as many trees were killed per ha in the unmanaged stands than in the managed stands: the average difference being 6.2 killed trees per ha, equivalent to 19% of the number of spruce trees felled by the first storm in the unmanaged stands. 6 Much higher numbers of trees were killed per ha in the stand edges than in the interiors of both the unmanaged and the managed stands.     

Application of architectural analysis and AMAPmod methodology to study dwarfing phenomenon: the branch structure of 'Royal Gala' apple grafted on dwarfing and non-dwarfing rootstock/interstock combinations

Architectural analysis was applied to study branch development of 'Royal Gala' apple trees grafted with dwarfing and non-dwarfing rootstock/interstock combinations, which had been chosen to produce trees with a wide range of vigour. Using AMAPmod methodology, the structure of 3-year-old branches was described at four levels of representation: branch; annual shoot; growth unit; and node. Three types of growth units were distinguished: extension growth unit (vegetative unit with internode extension); vegetative spur with minimal internode extension; and fruiting spur or bourse. The aim of the analysis was to describe exactly how the rootstock/interstock combinations affected the structure building process. The number of extension growth units, vegetative spurs and fruiting spurs per annual shoot changed over the years, but this was not affected by rootstock/interstock combination. Compared with MM.106 rootstock, M.9 rootstock reduced the number of nodes per extension growth unit. In most cases, rootstock/interstock combination had no effect on the linear relationship between extension growth unit length and node number (R(2) = 0.88). Average internode length depended on unit node number, with internodes being shorter for units with fewer nodes. Thus the difference in apple branch size induced by the rootstock/interstock combinations was mainly due to a reduction in the length and number of neoformed nodes produced on extension growth units. As percentage budbreak of axillary buds on extension growth units was not affected by rootstock/interstock combination, differences in numbers of axillary annual shoots per branch were entirely due to differences in the total numbers of nodes extended during the previous year.     

The Induction of Chromosomal Aberrations by Tetra Antibiotic in Bone Marrow Cells of Rats in Vivo

The aim of this study was to investigate the in vivo effects of tetra (tetralet) antibiotic on chromosomal aberrations (CA) in bone marrow cells of rats (Rattus norvegicus var. albinos). The tetra antibiotic significantly increased the percentage of abnormal cells and the chromosomal aberrations per cell (CA/cell) in bone marrow cells of rats at concentrations of 100 and 200 mg/kg body weight for 12 and 24 h treatment periods for each. In addition, the percentage of abnormal cells and the CA/cell increased dose-dependently for 12 h treatment period; in contrast, mitotic index was decreased when compared with negative control and solvent controls for 12-h treatment period. However, mitotic index increased depending on tetra antibiotic dose for 24-h treatment period.