BACKGROUND AND AIMS: Stomatal density (SD) generally decreases with rising atmospheric CO2 concentration, Ca. However, SD is also affected by light, air humidity and drought, all under systemic signalling from older leaves. This makes our understanding of how Ca controls SD incomplete. This study tested the hypotheses that SD is affected by the internal CO2 concentration of the leaf, Ci, rather than Ca, and that cotyledons, as the first plant assimilation organs, lack the systemic signal. METHODS: Sunflower (Helianthus annuus), beech (Fagus sylvatica), arabidopsis (Arabidopsis thaliana) and garden cress (Lepidium sativum) were grown under contrasting environmental conditions that affected Ci while Ca was kept constant. The SD, pavement cell density (PCD) and stomatal index (SI) responses to Ci in cotyledons and the first leaves of garden cress were compared. (13)C abundance (δ(13)C) in leaf dry matter was used to estimate the effective Ci during leaf development. The SD was estimated from leaf imprints. KEY RESULTS: SD correlated negatively with Ci in leaves of all four species and under three different treatments (irradiance, abscisic acid and osmotic stress). PCD in arabidopsis and garden cress responded similarly, so that SI was largely unaffected. However, SD and PCD of cotyledons were insensitive to Ci, indicating an essential role for systemic signalling. CONCLUSIONS: It is proposed that Ci or a Ci-linked factor plays an important role in modulating SD and PCD during epidermis development and leaf expansion. The absence of a Ci-SD relationship in the cotyledons of garden cress indicates the key role of lower-insertion CO2 assimilation organs in signal perception and its long-distance transport.

• MeSH
• Arabidopsis cytologie   účinky léků   MeSH
• buk (rod) cytologie   účinky léků   MeSH
• dehydratace MeSH
• Helianthus cytologie   účinky léků   MeSH
• kotyledon účinky léků   fyziologie   MeSH
• Lepidium cytologie   účinky léků   MeSH
• oxid uhličitý farmakologie   MeSH
• počet buněk MeSH
• průduchy rostlin cytologie   účinky léků   MeSH
• životní prostředí MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Stomata modulate the exchange of water and CO2between plant and atmosphere. Although stomatal density is known to affect CO2diffusion into the leaf and thus photosynthetic rate, the effect of stomatal density and patterning on CO2assimilation is not fully understood. We used wild types Col-0 and C24 and stomatal mutants sdd1-1 and tmm1 of Arabidopsis thaliana, differing in stomatal density and pattern, to study the effects of these variations on both stomatal and mesophyll conductance and CO2assimilation rate. Anatomical parameters of stomata, leaf temperature and carbon isotope discrimination were also assessed. Our results indicate that increased stomatal density enhanced stomatal conductance in sdd1-1 plants, with no effect on photosynthesis, due to both unchanged photosynthetic capacity and decreased mesophyll conductance. Clustering (abnormal patterning formed by clusters of two or more stomata) and a highly unequal distribution of stomata between the adaxial and abaxial leaf sides in tmm1 mutants also had no effect on photosynthesis. Except at very high stomatal densities, stomatal conductance and water loss were proportional to stomatal density. Stomatal formation in clusters reduced stomatal dynamics and their operational range as well as the efficiency of CO2transport.

• MeSH
• Arabidopsis genetika   metabolismus   MeSH
• fotosyntéza genetika   fyziologie   MeSH
• geneticky modifikované rostliny genetika   metabolismus   MeSH
• izotopy uhlíku metabolismus   MeSH
• oxid uhličitý metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• průduchy rostlin genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH

The initiation of stomata, microscopic valves in the epidermis of higher plants that control of gas exchange, requires a co-ordinated sequence of asymmetric and symmetric divisions, which is under tight environmental and developmental control. Arabidopsis leaves grown under elevated photosynthetic photon flux density have a higher density of stomata. STOMAGEN encodes an epidermal patterning factor produced in the mesophyll, and our observations indicated that elevated photosynthetic irradiation stimulates STOMAGEN expression. Our analysis of gain and loss of function of STOMAGEN further detailed its function as a positive regulator of stomatal formation on both sides of the leaf, not only in terms of stomatal density across the leaf surface but also in terms of their stomatal index. STOMAGEN function was rate limiting for the light response of the stomatal lineage in the adaxial epidermis. Mutants in pathways that regulate stomatal spacing in the epidermis and have elevated stomatal density, such as stomatal density and distribution (sdd1) and too many mouth alleles, displayed elevated STOMAGEN expression, suggesting that STOMAGEN is either under the direct control of these pathways or is indirectly affected by stomatal patterning, suggestive of a feedback mechanism. These observations support a model in which changes in levels of light irradiation are perceived in the mesophyll and control the production of stomata in the epidermis by mesophyll-produced STOMAGEN, and whereby, conversely, stomatal patterning, either directly or indirectly, influences STOMAGEN levels.

• MeSH
• Arabidopsis genetika   růst a vývoj   metabolismus   účinky záření   MeSH
• fotosyntéza MeSH
• listy rostlin růst a vývoj   metabolismus   účinky záření   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• průduchy rostlin genetika   růst a vývoj   metabolismus   účinky záření   MeSH
• regulace genové exprese u rostlin účinky záření   MeSH
• signální transdukce MeSH
• světlo MeSH
• vývojová regulace genové exprese účinky záření   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Occurrence of stomata on both leaf surfaces (amphistomaty) promotes higher stomatal conductance and photosynthesis while simultaneously increasing exposure to potential disease agents in black cottonwood (Populus trichocarpa). A genome-wide association study (GWAS) with 2.2M single nucleotide polymorphisms generated through whole-genome sequencing found 280 loci associated with variation in adaxial stomatal traits, implicating genes regulating stomatal development and behavior. Strikingly, numerous loci regulating plant growth and response to biotic and abiotic stresses were also identified. The most significant locus was a poplar homologue of SPEECHLESS (PtSPCH1). Individuals possessing PtSPCH1 alleles associated with greater adaxial stomatal density originated primarily from environments with shorter growing seasons (e.g. northern latitudes, high elevations) or with less precipitation. PtSPCH1 was expressed in developing leaves but not developing stem xylem. In developing leaves, RNA sequencing showed patterns of coordinated expression between PtSPCH1 and other GWAS-identified genes. The breadth of our GWAS results suggests that the evolution of amphistomaty is part of a larger, complex response in plants. Suites of genes underpin this response, retrieved through genetic association to adaxial stomata, and show coordinated expression during development. We propose that the occurrence of amphistomaty in P. trichocarpa involves PtSPCH1 and reflects selection for supporting rapid growth over investment in immunity.

• MeSH
• alely MeSH
• celogenomová asociační studie MeSH
• druhová specificita MeSH
• fenotyp MeSH
• genotyp MeSH
• imunita rostlin genetika   MeSH
• jednonukleotidový polymorfismus genetika   MeSH
• kvantitativní znak dědičný MeSH
• podnebí MeSH
• Populus genetika   růst a vývoj   imunologie   fyziologie   MeSH
• průduchy rostlin genetika   fyziologie   MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné geny MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• rozvržení tělního plánu * MeSH
• vývoj rostlin MeSH
• zeměpis MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Stomatal ontogenesis, patterning, and function are hallmarks of environmental plant adaptation, especially to conditions limiting plant growth, such as elevated temperatures and reduced water availability. The specification and distribution of a stomatal cell lineage and its terminal differentiation into guard cells require a master regulatory protein phosphorylation cascade involving the YODA mitogen-activated protein kinase kinase kinase. YODA signaling results in the activation of MITOGEN-ACTIVATED PROTEIN KINASEs (MPK3 and MPK6), which regulate transcription factors, including SPEECHLESS (SPCH). Here, we report that acute heat stress affects the phosphorylation and deactivation of SPCH and modulates stomatal density. By using complementary molecular, genetic, biochemical, and cell biology approaches, we provide solid evidence that HEAT SHOCK PROTEINS 90 (HSP90s) play a crucial role in transducing heat-stress response through the YODA cascade. Genetic studies revealed that YODA and HSP90.1 are epistatic, and they likely function linearly in the same developmental pathway regulating stomata formation. HSP90s interact with YODA, affect its cellular polarization, and modulate the phosphorylation of downstream targets, such as MPK6 and SPCH, under both normal and heat-stress conditions. Thus, HSP90-mediated specification and differentiation of the stomatal cell lineage couples stomatal development to environmental cues, providing an adaptive heat stress response mechanism in plants.

• MeSH
• Arabidopsis fyziologie   MeSH
• buněčná diferenciace MeSH
• buněčné dělení MeSH
• buněčný rodokmen MeSH
• epigeneze genetická MeSH
• fosforylace MeSH
• kotyledon cytologie   MeSH
• MAP kinasy kinas (kinas) genetika   metabolismus   MeSH
• mitogenem aktivované proteinkinasy kinas metabolismus   MeSH
• mitogenem aktivované proteinkinasy metabolismus   MeSH
• mutace MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteiny tepelného šoku HSP90 genetika   metabolismus   MeSH
• průduchy rostlin cytologie   růst a vývoj   metabolismus   MeSH
• reakce na tepelný šok * MeSH
• regulace genové exprese u rostlin MeSH
• signální transdukce MeSH
• transkripční faktory bHLH metabolismus   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

BACKGROUND AND AIMS: The idea that genome (size) evolution in eukaryotes could be driven by environmental factors is still vigorously debated. In extant plants, genome size correlates positively with stomatal size, leading to the idea that conditions enabling the existence of large stomata in fossil plants also supported growth of their genome size. We test this inductive assumption in drought-adapted, prostrate-leaved Cape (South Africa) geophytes where, compared with their upright-leaved geophytic ancestors, stomata develop in a favourably humid microclimate formed underneath their leaves. METHODS: Stomatal parameters (leaf cuticle imprints) and genome size (flow cytometry) were measured in 16 closely related geophytic species pairs from seven plant families. In each pair, representing a different genus, we contrasted a prostrate-leaved species with its upright-leaved phylogenetic relative, the latter whose stomata are exposed to the ambient arid climate. KEY RESULTS: Except for one, all prostrate-leaves species had larger stomata, and in 13 of 16 pairs they also had larger genomes than their upright-leaved relatives. Stomatal density and theoretical maximum conductance were less in prostrate-leaved species with small guard cells (<1 pL) but showed no systematic difference in species pairs with larger guard cells (>1 pL). Giant stomata were observed in the prostrate-leaved Satyrium bicorne (89-137 µm long), despite its relatively small genome (2C = 9 Gbp). CONCLUSIONS: Our results imply that climate, through selection on stomatal size, might be able to drive genome size evolution in plants. The data support the idea that plants from 'greenhouse' geological periods with large stomata might have generally had larger genome sizes when compared with extant plants, though this might not have been solely due to higher atmospheric CO2 in these periods but could also have been due to humid conditions prevailing at fossil deposit sites.

• MeSH
• délka genomu MeSH
• fylogeneze MeSH
• genom rostlinný genetika   MeSH
• listy rostlin MeSH
• průduchy rostlin genetika   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Jihoafrická republika MeSH

Only very few comparative studies have been performed that evaluate general trends of virus growth under 3D in comparison with 2D cell culture conditions. The aim of this study was to investigate differences when four animal viruses are cultured in 2D and 3D. Suid herpesvirus 1 (SuHV-1), Vesicular stomatitis virus (VSIV), Bovine adenovirus (BAdV) and Bovine parainfluenza 3 virus (BPIV-3) were cultivated in 3D rotating wall vessels (RWVs) and conventional 2D cultures. The production of virus particles, the portion of infectious particles, and the infectious growth curves were compared. For all viruses, the production of virus particles (related to cell density), including the non-infectious ones, was lower in 3D than in 2D culture. The production of only infectious particles was significantly lower in BAdV and BPIV-3 in 3D cultures in relation to cell density. The two cultivation approaches resulted in significantly different virus particle-to-TCID50 ratios in three of the four viruses: lower in SuHV-1 and BPIV-3 and higher in BAdV in 3D culture. The infectious virus growth rates were not significantly different in all viruses. Although 3D RWV culture resulted in lower production of virus particles compared to 2D systems, the portion of infectious particles was higher for some viruses.

• MeSH
• Atadenovirus růst a vývoj   fyziologie   ultrastruktura   MeSH
• buněčné kultury * přístrojové vybavení   metody   MeSH
• buňky MDCK MeSH
• Cercopithecus aethiops MeSH
• kultivace virů metody   MeSH
• prasata MeSH
• prasečí herpesvirus 1 růst a vývoj   fyziologie   ultrastruktura   MeSH
• psi MeSH
• replikace viru MeSH
• skot MeSH
• Vero buňky MeSH
• virus bovinní parainfluenzy 3 růst a vývoj   fyziologie   ultrastruktura   MeSH
• virus vezikulární stomatitidy, kmen Indiana růst a vývoj   fyziologie   ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• psi MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

Bisfosfonáty jsou léky využívané především v onkologii a osteologii pro terapii chorob spojených se zvýšenou kostní resorpcí a ztrátou kostní hmoty a pro předcházení komplikací, která tato onemocnění doprovázejí. V posledních letech je pozornost odborné stomatologické veřejnosti zaměřena na poměrně recentně popsaný nežádoucí účinek těchto léků v dutině ústní – na osteonekrózu čelistí. Autoři se v tomto sdělení zabývají vlivem bisfosfonátů na orální zdraví, a to nejen ve smyslu jejich patologického působení, ale i možných terapeutických účinků.

• Klíčová slova
• osteonekróza čelistí, nežádoucí účinky, léčba bisfosfonáty,
• MeSH
• bisfosfonáty farmakologie   klasifikace   škodlivé účinky   MeSH
• inhibitory kostní resorpce škodlivé účinky   MeSH
• lidé MeSH
• nemoci čelistí farmakoterapie   prevence a kontrola   MeSH
• osteonekróza prevence a kontrola   MeSH
• stomatitida prevence a kontrola   MeSH
• Check Tag
• lidé MeSH

• MeSH
• centrifugace - gradient hustoty MeSH
• cytosin MeSH
• dextrany farmakologie   MeSH
• ethylaminy MeSH
• interferony biosyntéza   MeSH
• L buňky (buněčná linie) metabolismus   MeSH
• molekulová hmotnost MeSH
• nukleosidy MeSH
• poly I-C farmakologie   MeSH
• polynukleotidy MeSH
• ribonukleasy MeSH
• sacharosa MeSH
• spektrofotometrie MeSH
• ultracentrifugace MeSH
• virus vezikulární stomatitidy, kmen Indiana MeSH

• MeSH
• centrifugace - gradient hustoty MeSH
• cytosin MeSH
• dextrany farmakologie   MeSH
• ethylaminy MeSH
• interferony biosyntéza   MeSH
• L buňky (buněčná linie) metabolismus   MeSH
• molekulová hmotnost MeSH
• nukleosidy MeSH
• poly I-C farmakologie   MeSH
• polynukleotidy MeSH
• ribonukleasy MeSH
• sacharosa MeSH
• spektrofotometrie MeSH
• ultracentrifugace MeSH
• virus vezikulární stomatitidy, kmen Indiana MeSH