Factors affecting in vitro regeneration in the model tree Populus trichocarpa I. Medium,environment, and hormone controls on organogenesis

In Vitro Cellular & Developmental Biology - Plant - In preparation for a major GWAS (Genome Wide Association Study) of plant regeneration and transformation, a large number of factors were...     

Quantitative genetic architecture of adaptive phenology traits in the deciduous tree,Populus trichocarpa (Torr. and Gray)

In a warming climate, the ability to accurately predict and track shifting environmental conditions will be fundamental for plant survival. Environmental cues define the transitions between growth and dormancy as plants synchronise development with favourable environmental conditions, however these cues are predicted to change under future climate projections which may have profound impacts on tree survival and growth. Here, we use a quantitative genetic approach to estimate the genetic basis of spring and autumn phenology in Populus trichocarpa to determine this species capacity for climate adaptation. We measured bud burst, leaf coloration, and leaf senescence traits across two years (2017–2018) and combine these observations with measures of lifetime growth to determine how genetic correlations between phenology and growth may facilitate or constrain adaptation. Timing of transitions differed between years, although we found strong cross year genetic correlations in all traits, suggesting that genotypes respond in consistent ways to seasonal cues. Spring and autumn phenology were correlated with lifetime growth, where genotypes that burst leaves early and shed them late had the highest lifetime growth. We also identified substantial heritable variation in the timing of all phenological transitions (h² = 0.5–0.8) and in lifetime growth (h² = 0.8). The combination of additive variation and favourable genetic correlations in phenology traits suggests that populations of cultivated varieties of P. Trichocarpa may have the capability to adapt their phenology to climatic changes without negative impacts on growth.Subject terms: Plant breeding, Forest ecology, Evolutionary genetics     

Factors affecting the genetic load in Drosophila: synergistic epistasis and correlations among fitness components

Two factors that can affect genetic load, synergistic epistasis and sexual selection, were investigated in Drosophila melanogaster. A set of five chromosomal regions containing visible recessive mutations were put together in all combinations to create a full set of 32 homozygous lines fixed for different numbers of known mutations. Two measures of fitness were made for each line: productivity (a combined measure of fecundity and egg-to-adult survivorship) and competitive male mating success. Productivity, but not male mating success, showed a pattern of strong average synergistic epistasis, such that the log fitness declined nonlinearly with increasing numbers of mutations. Synergistic epistasis is known to reduce the mutation load. Both fitness components show some positive and some negative interactions between specific sets of mutations. Furthermore, alleles with deleterious effects on productivity tend to also diminish male mating success. Given that male mating success can affect relative fitness without changing the mean productivity of a population, these additional effects would lead to lower frequencies and lower fixation rates of deleterious alleles without higher costs to the mean fitness of the population.     

Optimization of in vitro micropropagation and regeneration for Populus × interamericana and Populus × euramericana hybrids (P. deltoides, P. trichocarpa, and P. nigra)

A rapid and efficient micropropagation method has been established for six European poplar cultivars of economic interest - four Populus 2 interamericana and two Populus 2 euramericana. Using a three-step procedure, we were able to regenerate plantlets from callus and acclimate them within 4 months. In the first step, callogenesis was induced when explants were cultured for 25 days on culture medium supplemented with 10 µM !-naphthaleneacetic acid and 5 µM N⁶(2-isopentenyl)adenine. Bud regeneration followed by shoot elongation was then obtained from callus tissue by combining the cytokinin-like compound thidiazuron with the surfactant Pluronic F-68 at concentrations adjusted for each cultivar. The usefulness of this procedure in the area of genetic engineering is discussed.     

Factors affecting in vitro regeneration of Ficus carica L. and genetic fidelity studies using molecular marker

Journal of Plant Biochemistry and Biotechnology - A facile method for regeneration of fig (Ficus carica L.) is in demand given the inability of the varieties having persistent type fruiting habit...     

Chloroplast DNA variation in Populus. II. Interspecific restriction fragment polymorphisms and genetic relationships among Populus deltoides,P. nigra,P. maximowiczii,and P. x canadensis

Restriction fragment analysis was conducted to determine interspecific chloroplast DNA (cpDNA) variation and genetic relationships among Populus deltoides, P. nigra, P. x canadensis (P. deltoides x P. nigra), and P. maximowiczii. Total cellular DNAs of these poplars were digested with 16 restriction endonucleases, and Southern blots of the restriction digests were probed with six different cloned cpDNA fragments from Petunia. P. deltoides, P. nigra, and P. maximowiczii each had a distinct chloroplast genome, separated by many restriction-site and restriction-fragment-length mutations, predominantly in the large single-copy region of the genome. P. x canadensis shared the same cpDNA restriction fragment patterns as P. deltoides var. deltoides. P. nigra was most diverged from P. deltoides, and P. deltoides showed close cpDNA relationships to P. maximowiczii. Nucleotide substitutions per site in cpDNA were 0.0036 between P. deltoides and P. maximowiczii, 0.0071 between P. nigra and P. maximowiczii, and 0.0077 between P. deltoides and P. nigra. We suggest that P. nigra should be classified in a new separate section, the Nigrae.     

A novel population balance model to investigate the kinetics of in vitro cell proliferation: part II. Numerical solution, parameters' determination, and model outcomes

Based on the general theoretical model developed in Part I of this work, a series of numerical simulations related to the in vitro proliferation kinetics of adherent cells is here presented. First the complex task of assigning a specific value to all the parameters of the proposed population balance (PB) model is addressed, by also highlighting the difficulties arising when performing proper comparisons with experimental data. Then, a parametric sensitivity analysis is performed, thus identifying the more relevant parameters from a kinetics perspective. The proposed PB model can be adapted to describe cell growth under various conditions, by properly changing the value of the adjustable parameters. For this reason, model parameters able to mimic cell culture behavior under microgravity conditions are identified by means of a suitable parametric sensitivity analysis. Specifically, it is found that, as the volume growth parameter is reduced, proliferation slows down while cells arrest in G0/G1 or G2/M depending on the initial distribution of cell population. On the basis of this result, model capabilities have been tested by means of a proper comparison with literature experimental data related to the behavior of synchronized and not-synchronized cells under micro- and standard gravity levels.     

An interfacial equilibria model for the electrokinetic properties of a fat emulsion. Part II: Magnesium,zinc and proton interactions with the interface

Abstract

The semi-empirical thermodynamic model reported in an earlier paper (Hall et al., 1991) is further developed to describe the zeta potential behaviour of an intravenous fat emulsion in the presence of magnesium and zinc cations. The effect of interfacial protonation is also explored. We have now established that a previously reported formation constant for the calcium interaction is actually a conditional value and together with the new data for zinc and magnesium, overall formation constants are calculated.     

In vitro propagation and assessment of genetic uniformity along with chemical characterization in Hildegardia populifolia (Roxb.) Schott & Endl.: a critically endangered medicinal tree

In Vitro Cellular & Developmental Biology - Plant - Hildegardia populifolia (Roxb.) Schott & Endl. is a critically endangered medicinal tree species which also provide high-quality...     

Protein-tyrosyl radical interactions in photosystem II studied by electron spin resonance and electron nuclear double resonance spectroscopy: comparison with ribonucleotide reductase and in vitro tyrosine.

The stable tyrosine radical in photosystem II, YD*, has been studied by ESR and ENDOR spectroscopies to obtain proton hyperfine coupling constants from which the electron spin density distribution can be deduced. Simulations of six previously published ESR spectra of PSII (one at Q band; five at X band, of which two were after specific deuteration and two others were of oriented membranes) can be achieved by using a single set of magnetic parameters that includes anisotropic proton hyperfine tensors, an anisotropic g tensor, and noncoincident axis systems for the g and A tensors. From the spectral simulation of the oriented samples, the orientation of the phenol head group of YD* with respect to the membrane plane has been determined. A similar orientation for YZ*, the redox-active tyrosine in PSII that mediates electron transfer between P680 and the oxygen-evolving complex, is expected. ENDOR spectra of YD* in PSII preparations from spinach and Synechocystis support the set of hyperfine coupling constants but indicate that small differences between the two species exist. Comparison with the results of spectral simulations for tyrosyl radicals in ribonucleotide reductase from prokaryotes or eukaryotes and with in vitro radicals indicates that the spin density distribution remains that of an odd-alternant radical but that interactions with the protein can shift spin density within this basic pattern. The largest changes in spin density occur at the tyrosine phenol oxygen and at the ring carbon para to the oxygen, which indicates that mechanisms exist in the protein environment for fine-tuning the chemical and redox properties of the radical species.     

Factors affecting the Abscission of Reproductive Organs in Yellow Lupms (Lupinus luteus L.): II. THE EFFECTS OF GROWTH SUBSTANCES, DEFOLIATION, AND REMOVAL OF LATERAL GROWTH

Abscission of flowers in Lupinus luteus L. (var. Weiko II) withoutgrowth of ovaries is followed by abscission of small pods (15–20mm. long). Normally flower abscission is much more pronouncedthan pod abscission. Abscission was delayed on plants from which laterals or theirterminal and axifliary buds were removed. Flower abscissionwas not affected, but pod abscission increased as a result ofdefoliation. When flowers at the base of the main inflorescence were replacedby auxins and anti-auxins flower abscission was induced in eitheran auxin pattern in which most of the flowers near the siteof application dropped, and pods developed on the apical whorls,or an anti-auxin pattern in which pods developed on basal whorlsnear the site of application but not higher up. The anti-auxinpattern was similar to the pattern of abscission normally inducedby developing pods on basal whorls. -Naphthylacetic acid (NAA) was much more effective in inducingabscission than ß-indolylacetic acid (IAA). 2:3:5-triiodobenzoicacid (TIBA), NAA, and IAA applied in mixtures at various concentrationsacted mainly antagonistically, i.e. the abscission-inducingeffect of NAA and LAA was depressed in basal whorls, and inapical whorls the effect of TIBA was less prevalent. Consequentlythe effect of the mixtures on the total number of pods was aboutequal to that of the most active component by itself. All growth substances seemed to move much more efficiently inacropetal direction than in basipetal direction in the flowerstalk. Transport in lateral direction was very limited. The effect of growth substances applied on laterals was enhancedby defoliating the main 8tem. The influence of assimilates on flower and pod abscission andtransport of growth substances is discussed.     

Organ interactions in the regulation of hematopoiesis: in vitro interactions of bone, thymus, and spleen with bone marrow stem cells in normal, Sl/Sld and W/Wv mice.

Hematopoietic cell differentiation is influenced by organ-dependent microenvironmental factors as well as humoral regulators. A technique is described for examining certain aspects of the hemopoietic inductive microenvironment in vitro. Suspension and agar cultures of mouse bone marrow were used to study the effects of organ stromal factors on cellular proliferation and differentiation. Bone, spleen, and thymus fragments from irradiated mice were placed in direct contact with or separated by a Nuclepore membrane from syngeneic marrow cells growing in suspension cultures. Normal adult mouse bone and spleen influenced granulocytic differentiation as well as cell proliferation. In this system, bone marrow and organ fragments from W/Wv and SlSld mice behaved like those of their non-anemic littermates. The most prominent difference between W/Wv and Sl/Sla mice and their normal counterparts was observed in the inductionof CFU-C from splenic precursors un-er the influence of CSA. In both types of anemic mice, in vitro generation of CFU-C from spleen was abnormal in young animals but was corrected by four months of age.