This study focuses on voicing assimilation across word boundaries in the speech of second language (L2) users. We compare native speakers of British English to speakers of two West Slavic languages, Czech and Slovak, which, despite their many similarities, differ with respect to voicing assimilation rules. Word-final voicing was analysed in 30 speakers, using the static value of voicing percentage and the voicing profile method. The results of linear mixed-effects modelling suggest an effect of first language (L1) transfer in all L2 English speaker groups, with the tendency to assimilate being correlated with the strength of foreign accent. Importantly, the two language groups differed in assimilation strategies before sonorant consonants, as a clear effect of L1-based phonetic influence.

• MeSH
• akustika řeči * MeSH
• akustika MeSH
• dospělí MeSH
• fonetika * MeSH
• kvalita hlasu * MeSH
• lidé MeSH
• měření tvorby řeči MeSH
• mladý dospělý MeSH
• mnohojazyčnost * MeSH
• percepce řeči * MeSH
• počítačové zpracování signálu MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladý dospělý MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH
• Geografické názvy
• Česká republika MeSH
• Slovenská republika MeSH

The carbon-concentrating mechanisms (CCMs) of cyanobacteria counteract the low CO2 affinity and CO2:O2 selectivities of the Rubisco of these photolithotrophs and the relatively low oceanic CO2 availability. CCMs have a significant energy cost; if light is limiting, the use of N sources whose assimilation demands less energy could permit a greater investment of energy into CCMs and inorganic C (Ci) assimilation. To test this, we cultured Synechococcus sp. UTEX LB 2380 under either N or energy limitation, in the presence of NO3- or NH4+. When growth was energy-limited, NH4+-grown cells had a 1.2-fold higher growth rate, 1.3-fold higher dissolved inorganic carbon (DIC)-saturated photosynthetic rate, 19% higher linear electron transfer, 80% higher photosynthetic 1/K1/2(DIC), 2.0-fold greater slope of the linear part of the photosynthesis versus DIC curve, 3.5-fold larger intracellular Ci pool, and 2.3-fold higher Zn quota than NO3--grown cells. When energy was not limiting growth, there were not differences between NH4+- and NO3--grown cells, except for higher linear electron transfer and larger intracellular Ci pool.We conclude that, when energy limits growth, cells that use the cheaper N source divert energy from N assimilation to C acquisition and assimilation; this does not happen when energy is not limiting.

• MeSH
• amoniové sloučeniny metabolismus   MeSH
• dusičnany metabolismus   MeSH
• dusík metabolismus   MeSH
• energetický metabolismus * MeSH
• fotosyntéza * MeSH
• oxid uhličitý metabolismus   MeSH
• Synechococcus metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Photosynthetic bacteria emerged on Earth more than 3 Gyr ago. To date, despite a long evolutionary history, species containing (bacterio)chlorophyll-based reaction centers have been reported in only 6 out of more than 30 formally described bacterial phyla: Cyanobacteria, Proteobacteria, Chlorobi, Chloroflexi, Firmicutes, and Acidobacteria. Here we describe a bacteriochlorophyll a-producing isolate AP64 that belongs to the poorly characterized phylum Gemmatimonadetes. This red-pigmented semiaerobic strain was isolated from a freshwater lake in the western Gobi Desert. It contains fully functional type 2 (pheophytin-quinone) photosynthetic reaction centers but does not assimilate inorganic carbon, suggesting that it performs a photoheterotrophic lifestyle. Full genome sequencing revealed the presence of a 42.3-kb-long photosynthesis gene cluster (PGC) in its genome. The organization and phylogeny of its photosynthesis genes suggests an ancient acquisition of PGC via horizontal transfer from purple phototrophic bacteria. The data presented here document that Gemmatimonadetes is the seventh bacterial phylum containing (bacterio)chlorophyll-based phototrophic species. To our knowledge, these data provide the first evidence that (bacterio)chlorophyll-based phototrophy can be transferred between distant bacterial phyla, providing new insights into the evolution of bacterial photosynthesis.

• MeSH
• Bacteria cytologie   genetika   metabolismus   MeSH
• druhová specificita MeSH
• fluorescenční mikroskopie MeSH
• fluorometrie MeSH
• fotosystém II (proteinový komplex) genetika   metabolismus   MeSH
• fylogeneze * MeSH
• jezera mikrobiologie   MeSH
• modely genetické MeSH
• molekulární sekvence - údaje MeSH
• pravděpodobnostní funkce MeSH
• RNA ribozomální 16S genetika   MeSH
• sekvence nukleotidů MeSH
• sekvenční analýza DNA MeSH
• shluková analýza MeSH
• spektrální analýza MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Čína MeSH

In cereal grains, the maternal nucellar projection (NP) constitutes the link to the filial organs, forming a transfer path for assimilates and signals towards the endosperm. At transition to the storage phase, the NP of barley (Hordeum vulgare) undergoes dynamic and regulated differentiation forming a characteristic pattern of proliferating, elongating, and disintegrating cells. Immunolocalization revealed that abscisic acid (ABA) is abundant in early non-elongated but not in differentiated NP cells. In the maternally affected shrunken-endosperm mutant seg8, NP cells did not elongate and ABA remained abundant. The amounts of the bioactive forms of gibberellins (GAs) as well as their biosynthetic precursors were strongly and transiently increased in wild-type caryopses during the transition and early storage phases. In seg8, this increase was delayed and less pronounced together with deregulated gene expression of specific ABA and GA biosynthetic genes. We concluded that differentiation of the barley NP is driven by a distinct and specific shift from lower to higher GA:ABA ratios and that the spatial-temporal change of GA:ABA balances is required to form the differentiation gradient, which is a prerequisite for ordered transfer processes through the NP. Deregulated ABA:GA balances in seg8 impair the differentiation of the NP and potentially compromise transfer of signals and assimilates, resulting in aberrant endosperm growth. These results highlight the impact of hormonal balances on the proper release of assimilates from maternal to filial organs and provide new insights into maternal effects on endosperm differentiation and growth of barley grains.

• MeSH
• buněčná diferenciace fyziologie   MeSH
• gibereliny metabolismus   MeSH
• ječmen (rod) metabolismus   MeSH
• kyselina abscisová metabolismus   MeSH
• regulace genové exprese u rostlin fyziologie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Gemmatimonas phototrophica is, so far, the only described phototrophic species of the bacterial phylum Gemmatimonadetes. Its cells contain a unique type of photosynthetic complex with the reaction center surrounded by a double ring antenna, however they can also grow in the dark using organic carbon substrates. Its photosynthesis genes were received via horizontal gene transfer from Proteobacteria. This raises two questions; how the horizontally transferred photosynthesis apparatus has integrated into the cellular machinery, and how much light-derived energy actually contributes to the cellular metabolism? To address these points, the photosynthetic reactions were studied on several levels, from photophysics of the reaction center to cellular growth. Flash photolysis measurements and bacteriochlorophyll fluorescence kinetic measurements documented the presence of fully functional type-2 reaction centers with a large light harvesting antenna. When illuminated, the bacterial cells reduced their respiration rate by 58 ± 5%, revealing that oxidative phosphorylation was replaced by photophosphorylation. Moreover, illumination also more than doubled the assimilation rates of glucose, a sugar that is mostly used for respiration. Finally, light increased the growth rates of Gemmatimonas phototrophica colonies on agar plates. All the presented data provide evidence that photosynthetic complexes are fully integrated into cellular metabolism of Gemmatimonas phototrophica, and are able to provide a substantial amount of energy for its metabolism and growth.

• MeSH
• Bacteria chemie   metabolismus   MeSH
• bakteriální proteiny chemie   metabolismus   MeSH
• bakteriochlorofyly chemie   MeSH
• fluorescenční spektrometrie MeSH
• fosforylace MeSH
• fotolýza MeSH
• fotosyntetická reakční centra (proteinové komplexy) chemie   MeSH
• fotosyntéza MeSH
• kinetika MeSH
• oxidace-redukce MeSH
• Publikační typ
• časopisecké články MeSH

Aerobic anoxygenic photosynthetic bacteria are an important component of marine microbial communities. They produce energy in light using bacteriochlorophyll a containing photosystems. This extra energy provides an advantage over purely heterotrophic bacteria. One of the most intensively studied AAP bacteria is Dinoroseobacter shibae, a member of the environmentally important Roseobacter clade. Light stimulates its growth and metabolism, but the effect of light intensity remains unclear. Here, we show that an increase in biomass along an irradiance gradient followed the exponential rise to the maximum curve, with saturation at about 300 µmol photons m-2 s-1 , without any inhibition at light intensities up to 600 µmol photons m-2 s-1 . The cells adapted to higher irradiance by reducing pigmentation and increasing the electron transfer rate. This additional energy allowed D. shibae to redirect the metabolism of organic carbon sources such as glucose, leucine, glutamate, acetate and pyruvate toward anabolism, resulting in a twofold increase of their assimilation rates. We provide equations that can be feasibly incorporated into the existing model of D. shibae metabolism to further advance our understanding of the role of photoheterotrophy in the ocean.

• MeSH
• bakteriochlorofyl A metabolismus   MeSH
• biomasa MeSH
• energetický metabolismus fyziologie   MeSH
• fotosyntéza fyziologie   MeSH
• organické látky metabolismus   MeSH
• Roseobacter metabolismus   MeSH
• světlo MeSH
• transport elektronů fyziologie   MeSH
• vodní organismy metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• Klíčová slova
• enioanatomie,
• MeSH
• anatomie průřezová MeSH
• anatomie MeSH
• metafyzické vztahy mezi duší a tělem MeSH
• parapsychologie MeSH
• přenos energie MeSH
• projekty vizualizace člověka MeSH
• Publikační typ
• monografie MeSH

• Konspekt
• Anatomie člověka a srovnávací anatomie
• NLK Obory
• anatomie

• MeSH
• biochemie MeSH

• Konspekt
• Biochemie. Molekulární biologie. Biofyzika
• NLK Obory
• biochemie

Semidwarfing genes have improved crop yield by reducing height, improving lodging resistance, and allowing plants to allocate more assimilates to grain growth. In wheat (Triticum aestivum), the Rht18 semidwarfing gene was identified and deployed in durum wheat before it was transferred into bread wheat, where it was shown to have agronomic potential. Rht18, a dominant and gibberellin (GA) responsive mutant, is genetically and functionally distinct from the widely used GA-insensitive semidwarfing genes Rht-B1b and Rht-D1b In this study, the Rht18 gene was identified by mutagenizing the semidwarf durum cultivar Icaro (Rht18) and generating mutants with a range of tall phenotypes. Isolating and sequencing chromosome 6A of these "overgrowth" mutants showed that they contained independent mutations in the coding region of GA2oxA9GA2oxA9 is predicted to encode a GA 2-oxidase that metabolizes GA biosynthetic intermediates into inactive products, effectively reducing the amount of bioactive GA (GA1). Functional analysis of the GA2oxA9 protein demonstrated that GA2oxA9 converts the intermediate GA12 to the inactive metabolite GA110 Furthermore, Rht18 showed higher expression of GA2oxA9 and lower GA content compared with its tall parent. These data indicate that the increased expression of GA2oxA9 in Rht18 results in a reduction of both bioactive GA content and plant height. This study describes a height-reducing mechanism that can generate new genetic diversity for semidwarfism in wheat by combining increased expression with mutations of specific amino acid residues in GA2oxA9.

• MeSH
• centromera genetika   MeSH
• chromozomy rostlin MeSH
• gibereliny genetika   metabolismus   MeSH
• mapování chromozomů MeSH
• mutageneze MeSH
• oxygenasy se smíšenou funkcí genetika   metabolismus   MeSH
• polyploidie MeSH
• promotorové oblasti (genetika) MeSH
• pšenice genetika   růst a vývoj   metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• DNA genetika   MeSH
• genetické jevy MeSH
• genom MeSH
• geny fyziologie   MeSH
• proteiny genetika   MeSH
• RNA genetika   MeSH
• Publikační typ
• monografie MeSH

• Konspekt
• Obecná genetika. Obecná cytogenetika. Evoluce
• NLK Obory
• genetika, lékařská genetika