Systematic overview of Krigia (Asteraceae-Lactuceae)

Cytological and morphological variation among Krigia species is examined. Krigia exhibits a broad range of chromosome numbers including n = 4, 5, 6, 9, 10, 15, and 30. Section Krigia is characterized by reflexed phyllaries and a base chromosome number of x = 5, while section Cymbia is characterized by erect phyllaries and chromosome numbers of n = 4, 6, and 9. The micromorphological characteristics of achenes, pappus, styles, corolla, pollen, stomata, and trichomes are documented using scanning electron microscopy. Among these, the pappus shows the greatest diversity and three major types are identified: 1) a pappus of many bristles and scales, as in K. dandelion, K. montana, and K. biflora; 2) a pappus of five bristles and five scales, as in K. virginica and K. occidentalis; and 3) an absent or highly reduced pappus, as in the K. cespitosa complex and K. wrightii. Thirty-five cytological and morphological characters are subjected to phylogenetic analyses. The two sections, Krigia and Cymbia, form monophyletic lineages. Within section Krigia, the annual species, K. virginica, forms an independent clade, while the perennial species, K. dandelion, K. biflora, and K. montana, form a monophyletic clade. Krigia montana and K. biflora are identified as sister species and a hybrid between these has been identified. The hybrid is more similar morphologically to K. montana than K. biflora. Within section Cymbia, phylogenetic relationships among K. wrightii, K. occidentalis, and K. cespitosa are uncertain. Nine taxa of Krigia are herein recognized: K. dandelion, K. biflora, K. biflora var. viridis (comb. nov.), K. montana, K. virginica, K. wrightii (comb. nov.), K. occidentalis, K. cespitosa, and K. cespitosa f. gracilis (comb. nov.). Phylogenetic relationships among 12 taxa of Krigia species are compared using various combinations of morphology, chloroplast DNA, and nuclear ribosomal DNA data. Tree topologies from different combinations of data are largely congruent. The most resolved phylogenetic tree is obtained using the combined data from morphology, chloroplast DNA, and nuclear ribosomal DNA.     

Biodiversity of Klebsormidium (Streptophyta) from alpine biological soil crusts (Alps,Tyrol, Austria,and Italy)

Forty Klebsormidium strains isolated from soil crusts of mountain regions (Alps, 600–3,000 m elevation) were analyzed. The molecular phylogeny (internal transcribed spacer rDNA sequences) showed that these strains belong to clades B/C, D, E, and F. Seven main (K. flaccidum, K. elegans, K. crenulatum, K. dissectum, K. nitens, K. subtile, and K. fluitans) and four transitional morphotypes (K. cf. flaccidum, K. cf. nitens, K. cf. subtile, and K. cf. fluitans) were identified. Most strains belong to clade E, which includes isolates that prefer humid conditions. One representative of the xerophytic lineage (clade F) as well as few isolates characteristic of temperate conditions (clades B/C, D) were found. Most strains of clade E were isolated from low/middle elevations (<1,800 m above sea level; a.s.l.) in the pine‐forest zone. Strains of clades B/C, D, and F occurred sporadically at higher elevations (1,548–2,843 m a.s.l.), mostly under xerophytic conditions of alpine meadows. Comparison of the alpine Klebsormidium assemblage with data from other biogeographic regions indicated similarity with soil crusts/biofilms from terrestrial habitats in mixed forest in Western Europe, North America, and Asia, as well as walls of buildings in Western European cities. The alpine assemblage differed substantially from crusts from granite outcrops and sand dunes in Eastern Europe (Ukraine), and fundamentally from soil crusts in South African drylands. Epitypification of the known species K. flaccidum, K. crenulatum, K. subtile, K. nitens, K. dissectum, K. fluitans, K. mucosum, and K. elegans is proposed to establish taxonomic names and type material as an aid for practical studies on these algae, as well as for unambiguous identification of alpine strains. New combination Klebsormidium subtile (Kützing) Mikhailyuk, Glaser, Holzinger et Karsten comb. nov. is made.     

The potential threat of algal blooms to the abalone (Haliotis midae) mariculture industry situated around the South African coast

Toxic algal blooms are common world-wide and pose a serious problem to the aquaculture and fishing industries. Dinoflagellate species such as Karenia brevis, Karenia mikimotoi, Heterosigma akashiwo and Chatonella cf. antiqua are recognised toxic species implicated in various faunal mortalities. Toxic blooms of Karenia cristata were observed on the south coast of South Africa for the first time in 1988 and were responsible for mortalities of wild and farmed abalone. K. cristata and various other dinoflagellate species common along the South African coast, as well as K. mikimotoi (Isolation site: Norway, Univ. of Copenhagen) and K. brevis (Isolation site: Florida, BIGELOW), were tested for toxicity by means of a bioassay involving Artemia larvae as well as abalone larvae and spat. K. cristata, like K. brevis, contains an aerosol toxin; however, the toxin present in K. cristata has not yet been isolated and remains unknown. K. brevis was, therefore, used to determine which developmental phase of the bloom would affect abalone farms most, and whether ozone could be used as an effective mitigating agent. Of the 17 dinoflagellate species tested, K. cristata, Akashiwo sanguinea, K. mikimotoi and K. brevis pose the greatest threat to the abalone mariculture industry. K. brevis was most toxic during its exponential and stationary phases. Results suggest that ozone is an effective mitigation agent but its economic viability for use on abalone farms must still be investigated.     

Regulation of H3K27me3 and H3K4me3 during early porcine embryonic development

The epigenetic marks H3K27me3 and H3K4me3 are important repressive and permissive histone modifications, respectively, which are involved in gene regulation such as Hox gene expression during embryonic development. In this study, we investigated the global levels of these two histone modifications. We also investigated the expression of H3K27me3's methyltransferase (EZH2), EZH2 co‐factors (EED and SUZ12) and demethylases (JMJD3 and UTX), as well as H3K4me3's methylases (ASH1L and MLL1) and demethylase (RBP2) in porcine pre‐implantation embryos. In addition, the expression of Hox genes, HOXA2, HOXA3, HOXA7, HOXA10, HOXB4, HOXB7, HOXC8, HOXD8, and HOXD10 was investigated. We found that global levels of H3K27me3 decreased from the 1‐ to the 4‐cell stage, corresponding to the time of major embryonic genome activation. Subsequently, the levels increased in hatched blastocysts, particularly in the trophectoderm. The expression levels of EZH2, EED, SUZ12, JMJD3, and UTX correlated well with these findings. The global levels of H3K4me3 decreased from the 1‐cell to the morula stage and increased in hatched blastocysts, especially in trophectoderm. A peak in expression of ASH1L was seen at the 4‐cell stage, but overall, expression of ASH1L, MLL1, and RBP2 correlated poorly with H3K4me3. HOXA3, A7, and B4 were expressed in 4‐cell embryos, and HOXA7, A10, B4, and D8 were expressed in hatched blastocysts, and did not correlate well to global methylation of H3K27me3 or H3K4me3. Thus, H3K4me3 may play a role in early porcine embryonic genome activation, whereas, H3K27me3 may be involved in initial cell lineage segregation in the blastocyst. Mol. Reprod. Dev. 77: 540–549, 2010. © 2010 Wiley‐Liss, Inc.     

ON THE IDENTITY OF KARLODINIUM VENEFICUM AND DESCRIPTION OF KARLODINIUM ARMIGER SP. NOV. (DINOPHYCEAE), BASED ON LIGHT AND ELECTRON MICROSCOPY,NUCLEAR‐ENCODED LSU RDNA,AND PIGMENT COMPOSITION1

An undescribed species of the dinoflagellate genus Karlodinium J. Larsen (viz. K. armiger sp. nov.) is described from Alfacs Bay (Spain), using light and electron microscopy, pigment composition, and partial large subunit (LSU) rDNA sequence. The new species differs from the type species of Karlodinium (K. micrum (Leadbeater et Dodge) J. Larsen) by lacking rows of amphiesmal plugs, a feature presently considered to be a characteristic of Karlodinium. In K. armiger, an outer membrane is underlain by a complex system of cisternae and vacuoles. The pigment profile of K. armiger revealed the presence of chlorophylls a and c, with fucoxanthin as the major carotenoid. Phylogenetic analysis confirmed K. armiger to be related to other species of Karlodinium; thus forming a monophyletic genus, which, in the LSU tree, occupies a sister group position to Takayama de Salas, Bolch, Botes et Hallegraeff. The culture used by Ballantine to describe Gymnodinium veneficum Ballantine (Plymouth 103) was examined by light and electron microscopy and by partial LSU rDNA. Ultrastructurally, it proved identical to K. micrum (cultures Plymouth 207 and K. Tangen KT‐77D, the latter also known as K‐0522), and in LSU sequence, differed in only 0.3% of 1438 bp. We consider the two taxa to belong to the same species. This necessitates a change of name for the most widely found species, K. micrum, to K. veneficum. The three genera Karlodinium, Takayama, and Karenia constitute a separate evolutionary lineage, for which the new family Kareniaceae fam. nov. is suggested.     

Androdioecy in Kryptolebias killifish and the evolution of self‐fertilizing hermaphroditism

Kryptolebias marmoratus is an important experimental fish, and is considered to represent the only vertebrate species comprising self‐fertilizing hermaphroditic individuals. Subsequent to the discovery of this unusual mode of reproduction, approximately 50 years ago, K. marmoratus has been the focus of a series of studies. However, little is known about the evolution of this rare reproduction mode, and data on the biology of closely related species are still unavailable. The present study aimed to histologically analyse the gonads of three K. marmoratus congeners (i.e. Kryptolebias ocellatus, Kryptolebias caudomarginatus, and Kryptolebias brasiliensis) to check the distribution of features related to hermaphroditism that are useful for forming hypotheses about the origin and evolution of the self‐fertilization mode of reproduction through the available phylogenies. The data obtained demonstrate that populations of K. caudomarginatus consist of males and hermaphrodites, which supports the hypothesis that hermaphroditism arose at the base of the clade containing K. caudomarginatus, K. marmoratus, and K. ocellatus as a first step towards a more advanced condition, uniquely shared by both K. marmoratus and K. ocellatus, in which males are rare or absent in natural populations, with the subsequent occurrence of self‐fertilization. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 344–349.     

Breeding behaviour of Kunzea pomifera (Myrtaceae): self-incompatibility, intraspecific and interspecific cross-compatibility

To examine breeding system characteristics of the endemic Australian prostrate shrub Kunzea pomifera, artificial hybridisations were undertaken using thirteen different genotypes of K. pomifera, to elucidate: (1) self-incompatibility, (2) intraspecific cross-compatibility in the species and (3) interspecific cross-compatibility with each of K. ambigua and K. ericoides. K. pomifera exhibited very low self-compatibility, with the barrier to self-fertilisation being prevention of pollen-tube growth in the style or ovary. Following intraspecific pollination amongst a number of different genotypes of K. pomifera, 38.4% of pollinated flowers developed fruit; arrest of compatible pollen-tubes in the style, preventing fertilisation, contributes to the low fruit set in this species. Interspecific compatibility was examined between K. pomifera (pistillate parent) and K. ambigua (staminate parent) where seed set per pollinated flower (4.47) was not significantly different from intraspecific crosses (4.66). In crosses between K. pomifera (pistillate parent) and K. ericoides as staminate plant, 0.037% of pollinated flowers produced fruit, with 0.0075 seeds per pollinated flower. Reproductive barriers between these two species were evident in the style of K. pomifera, where the growing tips of the K. ericoides pollen-tubes swelled and ceased to grow.     

环纹矮柳(杨柳科)的后选模式指定及形态描述订正

环纹矮柳(Salix annulifera C. MarquandAiry Shaw)的模式标本材料F. K. Ward 5870包括2个完全不同的种。根据深圳法规的相应条款,在此指定F. K. Ward 5870 (K-000335077)为S. annulifera的后选模式;将F. K. Ward 5870 (K-000335083)从S. annulifera中排除,并鉴定为藏南柳(S. austrotibetica N. Chao)。此外,对环纹矮柳的形态描述进行了相应的订正。     

巴斯德毕赤酵母不同生长阶段内参基因的筛选与验证

【背景】巴斯德毕赤酵母(Komagataella phaffii)是一种甲基营养型酵母,近年来作为生产重组蛋白和构建生物合成途径的细胞工厂受到广泛关注。实时荧光定量PCR (real-time quantitative PCR,RT-qPCR)是巴斯德毕赤酵母表达系统研究中一种快速、高效的基因表达水平检测技术,但需要进行归一化处理才能保证所得结果的可靠性。【目的】筛选并验证巴斯德毕赤酵母在不同生长阶段最稳定的内参基因用于精准归一化RT-qPCR的结果。【方法】通过转录组数据分析初步筛选出16个候选内参基因(rps8b、rpl35a、rpl10、eif5a、rpl19a、por1、rpl23b、0887、tif1、ole1、rpl14b、gs、sun、sdh2、trx1和ccp1)。通过RT-qPCR技术得到候选内参基因的C_t值,利用qBASE软件中的geNorm程序综合NormFinder算法评估内参基因的表达稳定性。【结果】通过geNorm分析得出精准归一化所需的最佳内参基因个数为2,最稳定的基因是rpl19a和tif1,NormFinder分析得到稳定性最高的内参基因为tif1。此外,利用甲酸脱氢酶编码基因fdh和乙醇脱氢酶甲醛脱氢酶双功能酶的编码基因afdh对候选内参基因进行验证。【结论】巴斯德毕赤酵母不同生长阶段的RT-qPCR进行精准归一化需要tif1和rpl19a这2个内参基因,为相关功能基因的表达定量提供了可靠的分析依据,补充了RT-qPCR分析中的内参基因,为巴斯德毕赤酵母不同生长阶段的基因表达调控及其应用研究提供了新的参考。     

Interactive effects of potassium and sodium on root growth and expression of K/Na transporter genes in rice

Sufficient supply of potassium (K) can alleviate the adverse effects of excess sodium (Na) on plant growth. However, it remains unclear if such a beneficial function is related to regulation of root growth and/or expression of K/Na transporters. Herein we report the responses of a rice cultivar, which was pretreated with normal nutrient solution for 1 month, to three levels of Na (0, 25, and 100 mM) without or with supply of K for 9 days. High Na (100 mM) significantly decreased plant growth, root activity, and total K uptake, and increased biomass ratio of roots to shoots. Short-term removal of K supply (9 days) did not affect root morphology and biomass ratio of roots to shoots, but decreased root activity of seedlings grown in high Na solution. K deficiency increased uptake of Na and transport of K from roots to shoots. Moreover, expression of OsHAK1, a putative K transporter gene, was upregulated by low Na (25 mM) and downregulated by high Na (100 mM) in roots. In leaves, its expression was suppressed by the Na treatments when K supply was maintained. Expression of OsHKT2;1, which encodes a protein that acts mainly as a Na transporter, was downregulated by high Na, but was enhanced by K deficiency both in roots and leaves. Expression of five other putative K/Na transporter or Na⁺/H⁺ genes, OsHKT1;1, OsHKT1;2, OsHKT2;3, OsNHX1, and OsSOS1, was not affected by the treatments. The results suggest that OsHAK1 and OsHKT2;1 were involved in the interactive effects of K and Na on their uptake and distribution in rice. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Different maternal genome donor to Kengyilia species inferred from chloroplast trnL-F sequences

To reveal the maternal donor of species in genus Kengyilia, the chloroplast trnL-F sequences of 14 Kengyilia species and several related diploid species were analyzed by using Maximum Parsimony (MP) and Bayesian Inference (BI) methods. The species in Kengyilia were clustered in different clades, which indicated that Agropyron (P) is the likely maternal genome donor to Kengyilia melanthera, K. mutica and K. thoroldiana, while the maternal donor to Kengyilia batalinii, K. nana, K. kokonorica, K. kaschgarica, K. hirsuta, K. alatavica, K. gobicola, K. zhaosuensis, K. rigidula, K. longiglumis and K. grandiglumis was St or Y Roegneria genome.     

Ion transport and regulation ofTetrahymena pyriformis in isotonic and hypotonic media

Summary The ion and volume regulatory mechanisms ofTetrahymena pyriformis were studied in normal or hypotonic nutrient media and in isotonic inorganic media with different Na/K ratios, in conjunction with the effects of a general metabolic inhibitor (low temperature) and a specific inhibitor (iodoacetate). For K two mechanisms of active influx were found: The first is sensitive to IAc and seems to be the basic mechanism for the maintenance of the K_i/K_o gradient. The second is sensitive to cooling and related to the function of the contractile vacuole; it is also responsible for the high intracellular levels of K. The passive K efflux seems to be a basic factor for volume regulation, together with the contractile vacuole. It increases in hypotonic media and this seems to be related to structural changes of the membranes occurring in hypotonic media. For Na two mechanisms of active transport were also found: One for active Na efflux with highK _m, which is associated with the contractile vacuole and another, for active Na influx with lowK _m, which is inhibited by high levels of intracellular K.The electrochemical potentials of Na and K and the membrane potential (Cl Nernst potential) were also studied in isotonic inorganic media. The membrane is negatively polarized, except if Na_o<5 mM when it becomes positive. In normal conditions, Na is transported outwards actively and leaks passively, while K is transported inwards actively and leaks 56 times more rapidly than Na ions.A model for the overall transport and regulation of ions inTetrahymena is proposed.Abbreviations IAc iodoacetate - PCV packed cell volume - Na _i,K _i,Cl intracellular concentrations ofNa ⁺,K ⁺,Cl ^–, respectively - Na _o,K _o, Cl_o extracellular concentrations of Na⁺, K⁺, Cl^–, respectively - DR distribution ratio - HyN hypotonic nutrient medium - IsN isotonic nutrient medium - HyS IsS hypotonic, and isotonic salt medium, respectively     

Molecular phylogeny of African hinge‐back tortoises (Kinixys): implications for phylogeography and taxonomy (Testudines: Testudinidae)

We examine the phylogeography, phylogeny and taxonomy of hinge‐back tortoises using a comprehensive sampling of all currently recognized Kinixys species and subspecies and sequence data of three mitochondrial DNA fragments (2273 bp: 12S rRNA, ND4 + adjacent DNA coding for tRNAs, cytb) and three nuclear loci (2569 bp: C‐mos, ODC, R35). Combined and individual analyses of the two data sets using Bayesian and Maximum Likelihood methods suggest that the savannah species of Kinixys are paraphyletic with respect to the rainforest species K. homeana and K. erosa, and that the rainforest species may be derived from a savannah‐living ancestor. The previously recognized savannah species K. belliana was a conglomerate of three deeply divergent clades that we treat here as distinct species. We restrict the name K. belliana (Gray, 1830) to hinge‐back tortoises ranging from Angola to Burundi, while five‐clawed hinge‐back tortoises from the northernmost part of the formerly recognized range of K. belliana, together with four‐clawed tortoises from West Africa, are assigned to the species K. nogueyi (Lataste, 1886). These two species are allied to K. spekii, whereas Southeast African and Malagasy hinge‐back tortoises formerly lumped together with K. belliana represent the distinct species K. zombensis Hewitt, 1931, which is sister to K. lobatsiana. The latter two species together constitute the sister group of the rainforest species K. homeana and K. erosa. Mitochondrial data suggest that K. natalensis has a basal phylogenetic position in a clade embracing K. belliana sensu stricto, K. nogueyi and K. spekii, while nuclear data and the two data sets combined favour a sister group relationship of K. natalensis to all other hinge‐back tortoises. Phylogeographic structure is present in all wide‐ranging species and correlates in K. homeana and K. erosa with the Dahomey Gap and former rainforest refugia. The Malagasy population of K. zombensis is weakly differentiated from its South African conspecifics and further sampling is needed to determine whether there is support for the subspecific distinctness of Malagasy tortoises.     

EVOLUTIONARY IMPLICATIONS OF INTRASPECIFIC CHLOROPLAST DNA VARIATION IN DWARF DANDELIONS (KRIGIA; ASTERACEAE)

Intraspecific chloroplast DNA polymorphisms were examined for 51 populations of seven species in the genus Krigia. A total of 1,100 restriction sites was surveyed and 46 of these were variable at the intraspecific level. Twenty-two of the variable sites were found within K. virginica, giving this species one of the highest levels of intraspecific chloroplast DNA divergence of any examined species. In contrast, no restriction site variation was detected within K. dandelion, K. wrightii, and K. occidentalis. Five polymorphisms were identified from the 16 populations of the K. cespitosa-gracilis complex, but no mutations distinguished the K. cespitosa and K. gracilis types. Krigia montana and K. biflora showed 11 and eight restriction site polymorphisms, respectively. The chloroplast genome of the hexaploid K. montana was derived from the diploid K. biflora rather than the tetraploid K. montana. High levels of polymorphism were found in species having different ploidy levels, such as K. virginica, K. biflora, and K. montana. Furthermore, most mutations found in these three species were recorded from the tetraploid lineages. As a result, evolutionary rates between different ploidy levels differ significantly. The chloroplast DNA restriction site data suggest that all surveyed populations of the autotetraploid K. virginica originated from a common ancestor. Our results also indicate that certain regions of the chloroplast genome have changed more rapidly than others and have the potential to resolve evolutionary questions at the population level.     

Chemical Response of the Toxic Dinoflagellate Karenia mikimotoi Against Grazing by Three Species of Zooplankton

We investigated the toxicity of Karenia mikimotoi toward three model grazers, the cladoceran Moina mongolica, the copepod Pseudodiaptomus annandalei, and the crustacean Artemia salina, and explored its chemical response upon zooplankton grazing. An induction experiment, where K. mikimotoi was exposed to grazers or waterborne cues from the mixed cultures revealed that K. mikimotoi might be toxic or nutritionally inadequate toward the three grazers. In general, direct exposure to the three grazers induced the production of hemolytic toxins and the synthesis of eicosapentaenoic acid (EPA). Both EPA and the hemolytic toxins from K. mikimotoi decreased the survival rate of the three grazers. In addition, the survival rates of M. mongolica, P. annandalei, and A. salina in the presence of induced K. mikimotoi that had previously been exposed to a certain grazer were lower than their counterparts caused by fresh K. mikimotoi, suggesting that exposure to some grazers might increase the toxicity of K. mikimotoi. The chemical response and associated increased resistance to further grazing suggested that K. mikimotoi could produce deterrents to protect against grazing by zooplankton and that the substances responsible might be hemolytic toxins and EPA.     

Development and application of LSU rRNA probes for Karenia brevis in the Gulf of Mexico, USA

The brevetoxin producing dinoflagellate, Karenia brevis, is the target of several monitoring and research programs in the Gulf of Mexico, where it forms extensive and frequently long-lived annual blooms that can cause human intoxication and fish kills, as well as severe economic losses to coastal communities. Rapid, reliable methods for the detection and enumeration of K. brevis cells, as well as their discrimination from morphologically similar species, are valuable tools for managers and scientists alike. Our aim was to produce a species-specific molecular probe that would serve as a tool to facilitate the efficient and reliable detection of K. brevis in the Gulf of Mexico. We sequenced a fragment of the large-subunit ribosomal RNA gene (LSU rDNA) from five K. brevis cultures isolated from the Texas Gulf coast, the Florida Gulf coast, and the Atlantic coast of Florida, and detected no differences among these isolates. A consensus sequence was thus compiled and compared to a previously published sequence from Karenia mikimotoi, the closest known phylogenetic relative to K. brevis, for the purpose of identifying unique K. brevis signature sequences. Fluorescently-labeled (FITC) oligonucleotide probes targeting these regions of the K. brevis LSU rRNA were designed to include at least two base pair differences, as compared to K. mikimotoi. Among seven probes designed, one uniquely identified all K. brevis isolates to the exclusion of all other species tested (Kbprobe-7), including a Gulf of Mexico K. mikimotoi isolate (Sarasota, FL) and several additional Gymnodinium species, as well as other dinoflagellate, diatom, and raphidophyte taxa. Importantly, K. brevis cells in samples taken during a 2001 bloom, fixed with a mixture of modified saline ethanol and 10% formalin, and stored at 4 °C for 7 months were successfully labeled with Kbprobe-7. In addition, preliminary analysis of labeled cells by flow cytometry revealed that K. brevis could be distinguished from K. mikimotoi in solution, suggesting other potential applications of this probe.     

Properties of a sucrose-tolerant Mutant of Saccharomyces cerevisiae

We characterized a sucrose-tolerant mutant of Saccharomyces cerevisiae, S22, that produces about four times as much acetate as the wild-type strain K9. We monitored the concentration of extracellular acetate during cultivation, and compared the gene expression ratios of S22 with those of K9 using DNA microarray. We propose that the sucrose tolerance of S22 may be related to the overexpression of the ENA1, ENA2, and ENA5 genes and some cell wall mannoprotein genes, and that the high acetate productivity of S22 is related to the overexpression of the ALD4 gene and oxidative phosphorylation genes.     

Potassium release rates from ustisols and their application

Second-order equations were used to characterize the potassium release rate for 20 low-hilly ustisols derived from Quaternary red clay in Zhejiang province, China. This was done under the condition of electric field strength of 44.4 and 88.8 V cm^–1. The values of the initial K release rate (v ₀) ranged from 1.17 to 21.23 and from 1.93 to 61.58, with an average of 5.36 and 9.54 mg kg^–1 min^–1 under the electric field strength of 44.4 and 88.8 V cm^–1, respectively. Six indices, including the relative grain yield, relative total dry matter yield and K uptake in NP treatments of 20 corn field experiments and available K, HNO₃ soluble K and slowly available K of soils were used to assess the practical applicability of K release rates. The correlation analysis showed that v ₀ was very significantly correlated (P=0.01) with the above six indices, and their correlation coefficients were 0.6275^**, 0.5645^**, 0.6624^**, 0.7277^**, 0.7843^** and 0.6299^**, respectively, under the electric strength of 44.4 V cm^–1. The v ₀ was related to relative total dry matter yield (P = 0.05, r = 0.5445^*) and very significantly correlated to the other five indices (relative grain yield, K uptake in NP treatment, available K, HNO₃ soluble K and slowly available K), with the correlation coefficients of 0.6064^**, 0.7216^**, 0.7523^**, 0.8202^** and 0.6686^**, respectively, under the electric strength of 88.8 V cm^–1. From the results, we conclude that v ₀ can be used to estimate the supplying power of soil K to annual crops such as corn, and to characterize soil K fertility.     

Properties of a Trifluoroleucine-Resistant Mutant of Saccharomyces cerevisiae

We characterized a trifluoroleucine-resistant mutant of Saccharomyces cerevisiae, TFL20, that has a mutation in the LEU4 gene. We monitored the concentration of extracellular i-AmOH and intracellular amino acids, and compared the ratios of gene expression in TFL20 with the wild-type strain, K30. We found that the LEU1, LEU2, and BAT1 genes were up-regulated in TFL20 for metabolism, and that TFL20 simultaneously produced as much i-AmOH and leucine as K30 does.     

Flagellar region 3b supports strong expression of integrated DNA and the highest chromosomal integration efficiency of the Escherichia coli flagellar regions

The Gram‐negative bacterium Escherichia coli is routinely used as the chassis for a variety of biotechnology and synthetic biology applications. Identification and analysis of reliable chromosomal integration and expression target loci is crucial for E. coli engineering. Chromosomal loci differ significantly in their ability to support integration and expression of the integrated genetic circuits. In this study, we investigate E. coli K12 MG1655 flagellar regions 2 and 3b. Integration of the genetic circuit into seven and nine highly conserved genes of the flagellar regions 2 (motA, motB, flhD, flhE, cheW, cheY and cheZ) and 3b (fliE, F, G, J, K, L, M, P, R), respectively, showed significant variation in their ability to support chromosomal integration and expression of the integrated genetic circuit. While not reducing the growth of the engineered strains, the integrations into all 16 target sites led to the loss of motility. In addition to high expression, the flagellar region 3b supports the highest efficiency of integration of all E. coli K12 MG1655 flagellar regions and is therefore potentially the most suitable for the integration of synthetic genetic circuits.