Concept of the influence of SARS -COV-2 viruses on cell malignancy

To date, in the context of the COVID 19 pandemic, there are rumors and speculations about the consequences of the infection, as well as a concern on growing cancer risk due to vaccines and vaccination. In this study we reviewed the concepts of the viral action on cancer development and analyzed the data on the possibility of the malignant effect of the SARS-CoV-2 virus on cells. Analysis of the literature data showed that SARS-CoV-2 damages cells, like other viruses, but does not lead to their mutations. There are no changes in DNA, there is only misregulation of repression and expression of the genome, a perversion of signaling intercellular interactions that disrupt the mechanisms of differentiation and specialization of cells. The need of viruses to multiply in cambial cells of tissues contributes to the induction of their proliferation and the lack of specialization. Thus, the available information on the cytopathic effects caused by viruses in cells infected with COVID-19 does not yet provide information on the malignant effect of SARS-CoV-2. Our study is aimed at collecting and analyzing data that are necessary for planning effective treatment of patients with COVID 19 and predicting outcomes in the long term after the disease.

Comparative Vegetative, Nutritional and Anatomical Study of Two Almond Varieties Grafted on Bitter Almond and Nemaguard Peach Rootstocks

A comparative study was conducted during the 2017/2018 and 2018/2019 growing seasons for Nonpareil and Ne Plus Ultra almond cvs grafted on Bitter almond and Nemaguard peach rootstocks at the Experimental Research Station of National Research Centre at Nubaria, El Behera governorate, Egypt. The comparison was evaluated through the grafting success percentage, vegetative growth, determination of some leaf mineral composition, as well as, the anatomical examination of scion/rootstock union zone and cross-section of leaves. The obtained results clarified that the grafting success percentage was significantly affected by the different used rootstocks. Using Bitter almond rootstock recorded the highest percentage of grafting success, leaf chlorophyll content, root length, and a number of lateral root /plant in both cultivars. Using Nemaguard peach rootstock recorded significantly the highest values of scion length, stem girth above and below union zone, number of branches and leaves/plant, leaf area as well as seedlings fresh and dry weight. Leaves of both cultivars grafted on Nemaguard peach rootstock recorded the highest concentrations of leaf mineral contents as compared to those grafted on Bitter almond rootstock. Cross-sections of the graft union zone were taken after 28 days and 6 months from grafting for anatomical analysis. The callus cells developed 28 days after grafting, but cambial cells between the rootstock and scion tissues did not occur in all scion/rootstock combinations. After 6 months of grafting, cambial cells were established, vascular differentiation was observed, regular parenchymatic tissue properties and sclerenchyma bundles were seen in the graft union. There was no problem in terms of compatibility of Nonpareil and Ne Plus Ultra on Bitter almond and Nemaguard peach rootstocks. Comparing leaf cross-sections of almond grafted on both rootstocks demonstrated that the density of mesophyll cells was affected as a consequence of the rootstock–scion interaction. Nemaguard peach rootstock can be recommended for grafting Nonpareil and Ne Plus Ultra almond cultivars under Nubaria conditions to produce vigorous trees.

Elucidation of the Structure of Lignin-Carbohydrate Complexes in Ginkgo CW-DHP by 13C-2H Dual Isotope Tracer

To elucidate the chemical linkages between lignin and carbohydrates in ginkgo cell walls, 13C-2H-enriched cell wall-dehydrogenation polymers (CW-DHP) were selectively prepared with cambial tissue from Ginkgo biloba L. by feeding D-glucose-[6-2H2], coniferin-[α-13C], and phenylalanine ammonia-lyase (PAL) inhibitor. The abundant detection of 13C and 2H confirmed that D-glucose-[6-2H2] and coniferin-[α-13C] were involved in the normal metabolism of ginkgo cambial cells that had been effectively labelled with dual isotopes. In the ginkgo CW-DHP, ketal and ether linkages were formed between the C-α of lignin side chains and carbohydrates, as revealed by solid state CP/MAS 13C-NMR differential spectroscopy. Furthermore, the DMSO/TBAH ionic liquids system was used to fractionate the ball-milled CW-DHP into three lignin-carbohydrate complex (LCC) fractions: glucan–lignin complex (GL), glucomannan–lignin complex (GML), and xylan–lignin complex (XL). The XRD determination indicated that the cellulose type I of the GL was converted into cellulose type II during the separation process. The molecular weight was in the order of Ac-GL > Ac-GML > XL. The 13C-NMR and 1H-NMR differential spectroscopy of 13C-2H-enriched GL fraction indicated that lignin was linked with cellulose C-6 by benzyl ether linkages. It was also found that there were benzyl ether linkages between the lignin side chain C-α and glucomannan C-6 in the 13C-2H-enriched GML fraction. The formation of ketal linkages between the C-α of lignin and xylan was confirmed in the 13C-2H-enriched XL fraction.

How Do Trees Grow in Girth? Controversy on the Role of Cellular Events in the Vascular Cambium

Radial growth has long been a subject of interest in tree biology research. Recent studies have brought a significant change in the understanding of some basic processes characteristic to the vascular cambium, a meristem that produces secondary vascular tissues (phloem and xylem) in woody plants. A new hypothesis regarding the mechanism of intrusive growth of the cambial initials, which has been ratified by studies of the arrangement of cambial cells, negates the influence of this apical cell growth on the expansion of the cambial circumference. Instead, it suggests that the tip of the elongating cambial initial intrudes between the tangential (periclinal) walls, rather than the radial (anticlinal) walls, of the initial(s) and its(their) derivative(s) lying ahead of the elongating cell tip. The new concept also explains the hitherto obscure mechanism of the cell event called ‘elimination of initials’. This article evaluates these new concepts of the cambial cell dynamics and offers a new interpretation for some curious events occurring in the cambial meristem in relation to the radial growth in woody plants.

Wound-inducible ANAC071 and ANAC096 transcription factors promote cambial cell formation in incised Arabidopsis flowering stems

ANAC071 and its homolog ANAC096 are plant-specific transcription factors required for the initiation of cell division during wound healing in incised Arabidopsis flowering stems and Arabidopsis hypocotyl grafts; however, the mechanism remains mostly unknown. In this study, we showed that wound-induced cambium formation involved cell proliferation and the promoter activity of TDR/PXY (cambium-related gene) in the incised stem. Prior to the wound-induced cambium formation, both ANAC071 and ANAC096 were expressed at these sites. anac-multiple mutants significantly decreased wound-induced cambium formation in the incised stems and suppressed the conversion from mesophyll cells to cambial cells in an ectopic vascular cell induction culture system (VISUAL). Our results suggest that ANAC071 and ANAC096 are redundantly involved in the process of “cambialization”, the conversion from differentiated cells to cambial cells, and these cambium-like cells proliferate and provide cells in wound tissue during the tissue-reunion process.

Ontogeny of divided vascular cylinders in Serjania: the rise of a novel vascular architecture in Sapindaceae

Sapindaceae lianas are remarkable for the diversity of cambial variants found in their stems. One of the family’s exclusive cambial variant is the divided vascular cylinder, which occurs in eight species of the genus Serjania. This cambial variant is marked by 5 peripheral vascular cylinders around a large pith. We performed a comparative developmental analysis, integrating traditional plant anatomy techniques with high-resolution X-ray micro-computed tomography to investigate the structure and development of the stems of three species with divided vascular cylinder. Our observations showed that the initial stages of stem development were similar to those described in the literature, however, on later developmental stages a central vascular cylinder appears in all species. The ontogeny of these stems are marked by three main processes: (i) dissection of vascular tissue from the peripheral vascular cylinders; (ii) development of new cambial arcs through the redifferentiation of pith cells; and (iii) recruitment of cambial cells from the inner portions of the vascular cambium of the peripheral vascular cylinders, forming a novel central vascular cylinder where the pith was, surrounded by five initial peripheral cylinders. As an ulterior developmental stage, some older stems also develop neoformations and connections between the different vascular cylinders. While our findings support previous descriptions of divided vascular cylinders, this is the first study illustrating the formation of the central vascular cylinder in this cambial variant. Our observations further corroborate that Serjania is the lineage with the highest and some of the most complex forms of cambial variants among all vascular plants.

Xylem and Phloem Formation Dynamics in Quercus ilex L. at a Dry Site in Southern Italy

Quercus ilex L. dieback has been recently reported at numerous Mediterranean sites. Wood and phloem formation dynamics and tree-ring series of anatomical traits can be used to evaluate growth conditions of trees. We monitored cambial activity in Q. ilex trees growing at a site in southern Italy in order to assess how xylem and phloem production are affected by harsh seasonal climatic variation during a dry year. We followed xylogenesis by counting the number of cambial cells and detecting the occurrence of post-cambial cells throughout the year. As phloem did not show clear growth rings and boundaries between them, we followed the development of phloem fibres—their morphological traits during development and the distance from the cambium served as a reference point to evaluate the phloem production during the year. We detected a multimodal pattern in cambial activity, with wood production in three periods of the year and consequent formation of intra-annual density fluctuations (IADFs). The lowest production of xylem cells was observed in the dry late spring and summer period (likely due to the low water availability), while the highest occurred in autumn (the wettest period). Although we could not differentiate between early and late phloem, the analysis of phloem traits was useful to follow the dynamics of phloem production, which is generally difficult in Mediterranean tree species. We found cambial production of phloem throughout the year, even in the periods without xylem production. The results showed that if tree growth was constrained by environmental limitations, the ratio between xylem to phloem cells decreased and, in the most severely affected trees, more cells were formed preferentially in the phloem compared to xylem. We also briefly report the way in which to solve technical problems with tissue preparation due to extreme hardness and to the peculiar structure of Q. ilex wood and outer bark.

VISUAL network analysis reveals the role of BEH3 as a stabilizer in the secondary vascular development in Arabidopsis

During secondary growth in plants, vascular stem cells located in the cambium continuously undergo self-renewal and differentiation throughout the lifetime. Recent cell-sorting technique enables to uncover transcriptional regulatory framework for cambial cells. However, the mechanisms underlying the robust control of vascular stem cells have not been understood yet. By coexpression network analysis using multiple transcriptome datasets of an ectopic vascular cell transdifferentiation system using Arabidopsis cotyledons, VISUAL, we newly identified a cambium-specific gene module from an alternative approach. The cambium gene list included a transcription factor BES1/BZR1 homolog 3 (BEH3), whose homolog BES1 is known to control vascular stem cell maintenance negatively. Interestingly, the vascular size of the beh3 mutants showed a large variation, implying the role of BEH3 as a stabilizer. BEH3 almost lost the transcriptional repressor activity and functioned antagonistically with other BES/BZR members via competitive binding to the same motif BRRE. Indeed, mathematical modeling suggests that the competitive relationship among BES/BZRs leads to the robust regulation of vascular stem cells.

The Impact of Changing Climate on the Cambial Activity during Radial Growth in Some Citrus Species

This study on radial growth in the stem of Citrus was carried out with an aim to notice the behavior of vascular cambium with respect to climatic and age effects. The fusiform initials vary in length from 137 to 363 μm in C. limon, 100 to 463 μm in C. paradisi, 137 to 413 μm in C. reticulata var. kinnow, and 137 to 375 μm in C. sinensis. The length rises with age, followed by decline and then again increase in C. limon. In C. paradisi, there is increase up to maximum and after decline is soon followed by constancy. In C. reticulata var. kinnow, increase in length from top to base in C. sinensis, increase up to maximum followed by a decline. Swelling of cambial cells occurs in the third week of March in C. limon, last week of March in C. paradisi, third week of April in C. reticulata var. kinnow, and second week of April in C. sinensis. The cambium turns dormant in early October in C. limon, late December in C. paradisi, early December in C. reticulata var. kinnow, and early November in C. sinensis. Thus, the cambium remains active for about 6 months in C. limon and C. sinensis, 9 months in C. paradisi, and 7 months in C. reticulata var. kinnow.

A quantitative test for heat-induced cell necrosis in vascular cambium and secondary phloem of Eucalyptus obliqua stems

Aims Exposure of Eucalyptus tree stems to the radiant heat of forest fires can kill cambial cells and their embedded regenerative meristems, thus preventing epicormic resprouting and recovery of the tree. Currently there is no tissue-level method to quantify the viability of cambial cells in Eucalyptus following heat exposure. The first aim of this study was to adapt and validate the tetrazolium reduction method of testing for cell viability in Eucalyptus. The second aim was to apply the method to establish a threshold level of cambium cell viability in Eucalyptus obliqua to enable the identification of a critical temperature. Methods The study used the tetrazolium reduction method to quantitatively determine phloem-cambium cell viability in Eucalyptus. Circular sections of bark with underlying phloem and cambium were cut from mature Eucalyptus obliqua and samples ranging in mass from 1 mg to 30 mg were exposed for 1 minute to temperature treatments ranging from 20°C to 85°C and kept for 20-22 hours at room temperature in 0.8% 2,3,5 triphenyl tetrazolium chloride (TTC) to test for cell viability. The 1,3,5 triphenyl tetrazolium formazan (TPF) formed was cold extracted with ethanol and quantified as absorbance at 485 nm. Important findings The TTC reduction method reliably quantified a decline in cell viability with rising temperature in tissue sections that included vascular cambium, and identified 60°C as the critical temperature for cambium-phloem cells of Eucalyptus species. Cell viability, calculated as [TPF Treatment°C] / [TPF 20°C], declined by 90% between 20°C and 85°C. The cell viability results confirmed that significant tissue necrosis occurred in Eucalyptus at temperatures between 50°C and 70°C, after one minute of in- vitro tissue heating. The decline in cell viability with increasing temperature shown by the TTC method was consistent with an independently derived count of live cells following temperature treatment and neutral red staining.