Leaf responses to soil water deficits: Comparative sensitivity of leaf expansion rate and leaf conductance in field-grown sunflower (Helianthus annuus L.)

The relative importance of changes in leaf expansion rate (LER) and leaf conductance (g₁) in the control of crop transpiration depends primarily on their sensitivity to soil water deficits. The aim of this paper was to quantify the responses of LER and g₁ to soil water deficits in sunflower (Helianthus annuus L.) under conditions of moderate (spring) and high (summer) evaporative demand. Soil water content, g₁, and LER were measured in dryland (DRY) and daily-irrigated (WET) crops established on a deep sandy-loam (Typic Xerofluvent) in a Mediterranean environment. There was no difference between g₁ of DRY and WET plants (p>0.20) in contrast with a highly significant difference in LER (p<0.001). Even under the harsh conditions of the summer experiment, g₁ did not respond to water deficit in a ten-day period in which LER of DRY plants was reduced to approx. 30% of that measured in WET controls. This field study indicates that g₁ plays at most a minor role in the control of sunflower transpiration in the pre-anthesis period and confirms the importance of leaf expansion in the regulation of gas exchange of expanding canopies subjected to soil water deficits.     

Cytological events induced by the inhibition of polyamine biosynthesis in thin cell layers of tobacco

Summary The proliferative growth of thin cell layers ofNicotiana tabacum cultured on a rhizogenic medium was markedly disturbed when polyamine biosynthesis was inhibited. Treatments with polyamine inhibitors led to cell expansion, accompanied by thinning of the cell wall and inhibition of cell division, and frequent cases of nucleolar extrusion, mainly in the parenchymal layer in contact with the medium. Nucleolar extrusion was not correlated with cell expansion. The highest incidence of nucleolar extrusion occurred when the pathways of putrescine biosynthesis were inhibited and when spermidine synthesis, via S-adenosylmethionine decarboxylase, was blocked. The duration of the growth phase with nuclear amitotic divisions was prolonged in the presence of the inhibitors and root meristem formation delayed. When polyamines were added with the inhibitors, all reactions proceeded as in the controls.Abbreviations CHA cyclohexylamine - DFMA DL--difluoromethyl-arginine - DFMO DL--difluoromethylornithine - LS longitudinal section - MGBG methylglyoxal-bis(guanylhydrazone) - PA polyamine - Pu putrescine - RLS radial longitudinal section - S.E. standard error - Spd spermidine     

Cellular expansion of MSCs: Shifting the regenerative potential

Mesenchymal-derived stromal or progenitor cells, commonly called “MSCs,” have attracted significant clinical interest for their remarkable abilities to promote tissue regeneration and reduce inflammation. Recent studies have shown that MSCs' therapeutic effects, originally attributed to the cells' direct differentiation capacity into the tissue of interest, are largely driven by the biomolecules the cells secrete, including cytokines, chemokines, growth factors, and extracellular vesicles containing miRNA. This secretome coordinates upregulation of endogenous repair and immunomodulation in the local microenvironment through crosstalk of MSCs with host tissue cells. Therapeutic applications for MSCs and their secretome-derived products often involve in vitro monolayer expansion. However, consecutive passaging of MSCs significantly alters their therapeutic potential, inducing a broad shift from a pro-regenerative to a pro-inflammatory phenotype. A consistent by-product of in vitro expansion of MSCs is the onset of replicative senescence, a state of cell arrest characterized by an increased release of proinflammatory cytokines and growth factors. However, little is known about changes in the secretome profile at different stages of in vitro expansion. Some culture conditions and bioprocessing techniques have shown promise in more effectively retaining the pro-regenerative and anti-inflammatory MSC phenotype throughout expansion. Understanding how in vitro expansion conditions influence the nature and function of MSCs, and their associated secretome, may provide key insights into the underlying mechanisms driving these alterations. Elucidating the dynamic and diverse changes in the MSC secretome at each stage of in vitro expansion is a critical next step in the development of standardized, safe, and effective MSC-based therapies.     

Cumulus expansion is impaired with advanced reproductive age due to loss of matrix integrity and reduced hyaluronan

Reproductive aging is associated with ovulatory defects. Age-related ovarian fibrosis partially contributes to this phenotype as short-term treatment with anti-fibrotic compounds improves ovulation in reproductively old mice. However, age-dependent changes that are intrinsic to the follicle may also be relevant. In this study, we used a mouse model to demonstrate that reproductive aging is associated with impaired cumulus expansion which is accompanied by altered morphokinetic behavior of cumulus cells as assessed by time-lapse microscopy. The extracellular matrix integrity of expanded cumulus–oocyte complexes is compromised with advanced age as evidenced by increased penetration of fluorescent nanoparticles in a particle exclusion assay and larger open spaces on scanning electron microscopy. Reduced hyaluronan (HA) levels, decreased expression of genes encoding HA-associated proteins (e.g., Ptx3 and Tnfaip6), and increased expression of inflammatory genes and matrix metalloproteinases underlie this loss of matrix integrity. Importantly, HA levels are decreased with age in follicular fluid of women, indicative of conserved reproductive aging mechanisms. These findings provide novel mechanistic insights into how defects in cumulus expansion contribute to age-related infertility and may serve as a target to extend reproductive longevity.     

Computational Fluid Dynamics Analysis of Upper Airway Changes after Protraction Headgear and Rapid Maxillary Expansion Treatment

Clinically, it is common for Class III patients with maxillary skeletal deficiency, which may result in a variety of adverse consequences. Protraction headgear and rapid maxillary expansion (PE) is an effective treatment, but its effect on upper airway hydrodynamics has not been reported. The main purpose of this study was to evaluate the changes of the flow in the upper airway after PE by computational fluid dynamics (CFD). The sample includes fifteen patients (6 males, 9 females, age 11.00 ± 1.00) and the paired T-test was used to analyze the differences between the measured data before and after treatment. The maximum flow velocity decreased from 8.42 ± 0.16 m/s to 6.98 ± 0.36 m/s (p < 0.05), and the maximum shear force decreased from 3.72 ± 1.48 Pa to 2.13 ± 0.18 Pa. The maximum negative pressure decreased from −101.78 ± 33.60 Pa to 58.15 ± 9.16 Pa, only the changes of velopharynx and glossopharynx were statistically significant; while the maximum resistance decreased from 140.88 ± 68.68 Pa/mL/s to 45.95 ± 22.96 Pa/mL/s. PE can effectively reduce the airflow resistance of the upper airway and the probability of airway collapse, thus improving the patient’s ventilation function.     

Selective incorporation of 5-hydroxytryptophan blocks long range electron transfer in oxalate decarboxylase

Oxalate decarboxylase from Bacillus subtilis is a binuclear Mn-dependent acid stress response enzyme that converts the mono-anion of oxalic acid into formate and carbon dioxide in a redox neutral unimolecular disproportionation reaction. A π-stacked tryptophan dimer, W96 and W274, at the interface between two monomer subunits facilitates long-range electron transfer between the two Mn ions and plays an important role in the catalytic mechanism. Substitution of W96 with the unnatural amino acid 5-hydroxytryptophan leads to a persistent EPR signal which can be traced back to the neutral radical of 5-hydroxytryptophan with its hydroxyl proton removed. 5-Hydroxytryptophan acts as a hole sink preventing the formation of Mn(III) at the N-terminal active site and strongly suppresses enzymatic activity. The lower boundary of the standard reduction potential for the active site Mn(II)/Mn(III) couple can therefore be estimated as 740 mV against the normal hydrogen electrode at pH 4, the pH of maximum catalytic efficiency. Our results support the catalytic importance of long-range electron transfer in oxalate decarboxylase while at the same time highlighting the utility of unnatural amino acid incorporation and specifically the use of 5-hydroxytryptophan as an energetic sink for hole hopping to probe electron transfer in redox proteins.     

Fibronectin turnover in human mesangial cell cultures as affected by Adriamycin

Fibronectin (FN) turnover and turnover changes induced by the anticancer drug Adriamycin (ADR) were measured in human mesangial cells (HMC) in vitro. HMC cultures synthesize cellular FN (2.2+-0.3% of totalprotein synthesis; n = 12) which is secreted and incorporated into a fibrillar extracellular matrix (ECM). A 24 hr incubation of HMC with ADR (0.5–5 g/ml) resulted in an accumulation of FN in the culture medium, with a maximum increase following 5 pglml(7.3+-2.3pg/cell vs. controls: 4.4+-1.9pg/cell; n= 10). Correspondingly, radioactively labeled immunoprecipitable FN was increased in a dosage-dependent manner in the culture medium up to 50% vs. controls. The incorporation of radioactively labeled FN into ECM was significantly increased following 2 g ADR/ml. In accordance, immunofZuorescence staining revealed an expansion ofpericellular FNfibers in cultures exposed to 2 g ADR/ml. Concomitant with the accumulation of extracelhlar FN, radioactively labeled FN in the cells was reduced by 22%. Qualitative characterization of FN patterns revealed a diminished number of degradation products in the culture medium ofADR-treated HMC. These data suggest thatADR interferes with the turnover of FN secreted by HMC in vitro in such a way that FN accumulates extracellularly. This in turn leads to a reduced FN synthesis. These findings are compatible with a loss of urinary FN degradation products accompanying the onset ofproteinuria in ADR-treated rats.Abbreviations ADR adriamycin - BSA bovine serum albumin - DTT dithiothreitol - ECM extracellular matrix - EDTA ethylenediamine tetraacetic acid disodium salt - ELISA enzyme-linked immunosorbent assay - FCS fetal calf serum - FITC fluorescein isothiocyanate - FN fibronectin - HMC human mesangial cell - PBS phosphate buffered saline - PMSF phenylmethylsulfonyl fluoride - SDS sodium dodecyl sulfate - SDS-PAGE SDS-polyacrylamide gel electrophoresis     

Palynological and palaeobotanical investigations in the area of the post-medieval Helsinki Old Town

Pollen, phytolith, and plant macrofossil analyses were carried out on the cultural layers of Helsinki Old Town excavated by the Helsinki City Museum and dated to the 15–17th centuries. Cultural mineral soil layers, a former ditch, a well, one waste pit, one waste heap and three house areas were investigated. The results show that-within certain limits-pollen in the mineral soil reflects the cultural changes of the local settlement from rural to urban. Among the main anthropogenic indicators, the high NAP (non-arboreal pollen) frequencies, the low pollen concentration values, and especially the high frequencies of Cichoriaceae (Liguliflorae) pollen should be emphasized. The macrofossil data were used to determine the species list of the herb pollen and to make a more detailed reconstruction of the local vegetation at Helsinki Old Town.     

黄瓜子叶扩张与细胞分裂素的关系

BA(benzyl adenine)专一性地促进离体黄瓜子叶的扩张。为了研究 BA 的作用机理,我们采用间接 EIISA 和 HPLC 的方法测定了子叶扩张过程中内源玉米素(Z)和玉米素核苷(ZR)含量的变化。离体黄瓜(Cucumis sativus,津研4号)子叶用10mg/l 的 BA 培养,72小时之后,处理子叶鲜重的增加比对照高70%。Z+ZR 在 BA 处理的子叶中有大量的积累。结果表明 BA 可能诱发了黄瓜子叶中的细胞分裂素生物合成和代谢的某些基因。