scholarly journals Microevolution of a Standard Strain ofCryptococcus neoformans Resulting in Differences in Virulence and Other Phenotypes

1998 ◽  
Vol 66 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Sarah P. Franzot ◽  
Jean Mukherjee ◽  
Robert Cherniak ◽  
Lin-Chi Chen ◽  
Junia S. Hamdan ◽  
...  
Keyword(s):  
Growth Rate ◽  
In Vitro Culture ◽  
Capsular Polysaccharide ◽  
Dna Typing ◽  
Carbon Assimilation ◽  
Drug Susceptibility ◽  
Proteinase Production ◽  
The Stability ◽  
Capsule Size

ABSTRACT Cryptococcus neoformans is a major fungal pathogen for patients with debilitated immune systems. However, no information is available on the stability of virulence or of phenotypes associated with virulence for C. neoformans laboratory strains. A serendipitous observation in our laboratory that one isolate of C. neoformans ATCC 24067 (strain 52D) became attenuated after continuous in vitro culture prompted us to perform a comparative study of nine strain 24067 isolates obtained from six different research laboratories. Each isolate was characterized by DNA typing, virulence for mice, proteinase production, extracellular protein synthesis, melanin synthesis, carbon assimilation pattern, antifungal drug susceptibility, colony morphology, growth rate, agglutination titers, phagocytosis by murine macrophages, capsule size, and capsular polysaccharide structure. All isolates had similar DNA typing patterns consistent with their assignment to the same strain, although minor chromosome size polymorphisms were observed in the electrophoretic karyotypes of two isolates. Several isolates had major differences in phenotypes that may be associated with virulence, including growth rate, capsule size, proteinase production, and melanization. These findings imply that C. neoformans is able to undergo rapid changes in vitro, probably as a result of adaptation to laboratory conditions, and suggest the need for careful attention to storage and maintenance conditions. In summary, our results indicate thatC. neoformans (i) can become attenuated by in vitro culture and (ii) is capable of microevolution in vitro with the emergence of variants exhibiting new genotypic and phenotypic characteristics.

scholarly journals In vitro culture as an aid to conservation of indigenous ferns: Diplazium proliferum

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Zubeir M. Golamaully ◽  
Vishwakalyan Bhoyroo ◽  
Nadeem Nazurally ◽  
Vineshwar Gopal
Keyword(s):  
Growth Rate ◽  
In Vitro Culture ◽  
Mercuric Chloride ◽  
Rare Species ◽  
Vascular Plants ◽  
Culture Media ◽  
Fungal Contamination ◽  
Increase Growth Rate ◽  
Growing Population

With the ever growing population and economic needs of Mauritius, the flora of Mauritius has never been in more danger and one group of vascular plants is even more in peril; ferns.<em> Diplazium proliferum</em> is indigenous to the Mascarene region and is considered as a rare species in Mauritius. The need to develop a tested <em>in vitro</em> propagation protocol is a must to protect the biodiversity of Mauritius. This experiment was geared towards the establishment of a proper sterilization technique and the effect of 6-benzylaminopurine (BAP) and light on <em>in vitro</em> culture of this fern. Sterilization with 0.05% Mercuric chloride was effective to eliminate fungal contamination and allow germination of spores. Culture media supplemented with BAP did not significantly increase growth rate of both gametophytes and sporophytes of<em> D. proliferum</em>. Present results suggest efficient sterilization methods to be a crucial stage for successful<em> in vitro r</em>egeneration of ferns. The established protocol will be used as an optimized baseline protocol for the propagation of other indigenous ferns.

scholarly journals Multivariate analysis as a tool for measuring the stability of morphometric traits in Lycopersicon plants from in vitro culture

2000 ◽  
Vol 23 (2) ◽  
pp. 479-493 ◽  
Author(s):  
Guillermo Pratta ◽  
Roxana Zorzoli ◽  
Liliana Amelia Picardi
Keyword(s):  
Multivariate Analysis ◽  
In Vitro Culture ◽  
Principal Component ◽  
Eigenvalues And Eigenvectors ◽  
Morphometric Traits ◽  
Regenerated Plants ◽  
Phenotypic Structure ◽  
Regeneration Cycle ◽  
The Stability

The phenotypic stability of morphometric traits in Lycopersicon spp. (stem perimeter at the base, middle and top, and number of flowers per cluster) was measured by multivariate analysis through a progeny test in order to estimate the genetic stability of these traits. Principal components were calculated for two groups of Lycopersicon spp., non-regenerated plants and the progeny of regenerated plants. Analysis of variance was performed to support principal component analysis. Both groups presented similar eigenvalues and eigenvectors, while no significant differences were found between any of the traits studied. These results indicated that the phenotypic structure was the same among the progeny of regenerated and non-regenerated plants, so that no variation would occur in in vitro culture. Multivariate analysis proved to be an appropriate methodology for the measurement of the stability of morphometric traits after one regeneration cycle.

scholarly journals Multiple Mechanisms Are Used for Growth Rate and Stringent Control of leuV Transcriptional Initiation inEscherichia coli

1999 ◽  
Vol 181 (18) ◽  
pp. 5771-5782 ◽  
Author(s):  
Dmitry K. Pokholok ◽  
Maria Redlak ◽  
Charles L. Turnbough ◽  
Sara Dylla ◽  
Walter M. Holmes
Keyword(s):  
Growth Rate ◽  
Binding Site ◽  
Transcription Initiation ◽  
Core Promoter ◽  
Cellular Level ◽  
Structural Variants ◽  
Stringent Control ◽  
The Stability

ABSTRACT Expression of the Escherichia coli leuV operon, which contains three tRNA1 Leu genes, is regulated by several mechanisms including growth-rate-dependent control (GRDC) and stringent control (SC). Structural variants of the leuV promoter which differentially affect these regulatory responses have been identified, suggesting that promoter targets for GRDC and SC may be different and that GRDC of the leuV promoter occurs in the absence of guanosine 3′,5′-bisdiphosphate. To determine the mechanisms of the leuV promoter regulation, we have examined the stability of promoter open complexes and the effects of nucleotide triphosphate (NTP) concentration on the efficiency of theleuV promoter and its structural variants in vitro and in vivo. The leuV promoter open complexes were an order of magnitude more stable to heparin challenge than those ofrrnBp 1. The major initiating nucleotide GTP as well as other NTPs increased the stability of the leuVpromoter open complexes. When the cellular level of purine triphosphates was increased at slower growth rates by pyrimidine limitation, a 10% reduction in leuV promoter activity was seen. It therefore appears that transcription initiation from theleuV promoter is less sensitive to changes in intracellular NTP concentration than that from rrnBp 1. Comparative analysis of regulation of the leuV promoter with and without upstream activating sequences (UAS) demonstrated that the binding site for factor of inversion stimulation (FIS) located in UAS is essential for maximal GRDC. Moreover, the presence of UAS overcame the effects of leuV promoter mutations, which abolished GRDC of the leuV core promoter. However, although the presence of putative FIS binding site was essential for optimal GRDC, both mutant and wild-type leuV promoters containing UAS showed improved GRDC in a fis mutant background, suggesting that FIS protein is an important but not unique participant in the regulation of the leuV promoter.

scholarly journals Dual Role of gnaA in Antibiotic Resistance and Virulence in Acinetobacter baumannii

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Qingye Xu ◽  
Tao Chen ◽  
Biyong Yan ◽  
Linyue Zhang ◽  
Borui Pi ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Capsular Polysaccharide ◽  
Treatment Options ◽  
Drug Susceptibility ◽  
Multidrug Resistant ◽  
Bacterial Virulence ◽  
Content Type ◽  
Evolution Experiment

ABSTRACT Acinetobacter baumannii is an important Gram-negative pathogen in hospital-related infections. However, treatment options for A. baumannii infections have become limited due to multidrug resistance. Bacterial virulence is often associated with capsule genes found in the K locus, many of which are essential for biosynthesis of the bacterial envelope. However, the roles of other genes in the K locus remain largely unknown. From an in vitro evolution experiment, we obtained an isolate of the virulent and multidrug-resistant A. baumannii strain MDR-ZJ06, called MDR-ZJ06M, which has an insertion by the ISAba16 transposon in gnaA (encoding UDP-N-acetylglucosamine C-6 dehydrogenase), a gene found in the K locus. The isolate showed an increased resistance toward tigecycline, whereas the MIC decreased in the case of carbapenems, cephalosporins, colistin, and minocycline. By using knockout and complementation experiments, we demonstrated that gnaA is important for the synthesis of lipooligosaccharide and capsular polysaccharide and that disruption of the gene affects the morphology, drug susceptibility, and virulence of the pathogen.

scholarly journals Effects of Increasing the Affinity of CarD for RNA Polymerase on Mycobacterium tuberculosis Growth, rRNA Transcription, and Virulence

2016 ◽  
Vol 199 (4) ◽  
Author(s):  
Ashley L. Garner ◽  
Jayan Rammohan ◽  
Jeremy P. Huynh ◽  
Lucas M. Onder ◽  
James Chen ◽  
...  
Keyword(s):  
Growth Rate ◽  
Mycobacterium Tuberculosis ◽  
Rna Polymerase ◽  
Site Directed Mutagenesis ◽  
Interacting Protein ◽  
Content Type ◽  
The Stability ◽  
Mouse Model Of Infection ◽  
Insight Into

ABSTRACT CarD is an essential RNA polymerase (RNAP) interacting protein in Mycobacterium tuberculosis that stimulates formation of RNAP-promoter open complexes. CarD plays a complex role in M. tuberculosis growth and virulence that is not fully understood. Therefore, to gain further insight into the role of CarD in M. tuberculosis growth and virulence, we determined the effect of increasing the affinity of CarD for RNAP. Using site-directed mutagenesis guided by crystal structures of CarD bound to RNAP, we identified amino acid substitutions that increase the affinity of CarD for RNAP. Using these substitutions, we show that increasing the affinity of CarD for RNAP increases the stability of the CarD protein in M. tuberculosis. In addition, we show that increasing the affinity of CarD for RNAP increases the growth rate in M. tuberculosis without affecting 16S rRNA levels. We further show that increasing the affinity of CarD for RNAP reduces M. tuberculosis virulence in a mouse model of infection despite the improved growth rate in vitro. Our findings suggest that the CarD-RNAP interaction protects CarD from proteolytic degradation in M. tuberculosis, establish that growth rate and rRNA levels can be uncoupled in M. tuberculosis and demonstrate that the strength of the CarD-RNAP interaction has been finely tuned to optimize virulence. IMPORTANCE Mycobacterium tuberculosis, the causative agent of tuberculosis, remains a major global health problem. In order to develop new strategies to battle this pathogen, we must gain a better understanding of the molecular processes involved in its survival and pathogenesis. We have previously identified CarD as an essential transcriptional regulator in mycobacteria. In this study, we detail the effects of increasing the affinity of CarD for RNAP on transcriptional regulation, CarD protein stability, and virulence. These studies expand our understanding of the global transcription regulator CarD, provide insight into how CarD activity is regulated, and broaden our understanding of prokaryotic transcription.

scholarly journals Toxicity effect of Auxemma oncocalyx fraction and its active principle oncocalyxone A on in vitro culture of caprine secondary follicles and in vitro oocyte maturation

2017 ◽  
Vol 38 (3) ◽  
pp. 1361 ◽  
Author(s):  
Johanna Leiva-Revilla ◽  
Jesús Cadenas ◽  
Luis Alberto Vieira ◽  
Claudio Cabral Campello ◽  
Juliana Jales de Hollanda Celestino ◽  
...  
Keyword(s):  
Growth Rate ◽  
In Vitro Culture ◽  
Oocyte Maturation ◽  
In Vitro Maturation ◽  
Cellular Proliferation ◽  
Control Group ◽  
Antral Follicles ◽  
Chromatin Configuration ◽  
In Vitro Oocyte Maturation

Crude extract of the heartwood of Auxemma oncocalyx (A. oncocalyx) and its main component i.e., Oncocalyxone A (onco A), have elevated antioxidant and anti-tumoral activity, but studies on the action of these drugs regarding folliculogenesis are lacking. The aim of this study was to evaluate the effect of A. oncocalyx and onco A on the in vitro culture of isolated secondary follicles and on the in vitro maturation of oocytes from caprine antral follicles grown in vivo. Isolated secondary follicles were randomly distributed in six groups; the non-cultured control was immediately fixed upon isolation. The remaining follicles were cultured for 7 days in ?-MEM+ alone (control) or supplemented with DMSO, doxorrubicin, A. oncocalyx or onco A. After culture, follicles were evaluated for antrum formation, growth rate, apoptosis (TUNEL) and cellular proliferation (PCNA), as well as gene expression of Bcl2 and Bax. Additionally, cumulus oocyte complexes (COCs) were aspirated and allocated into five treatments for in vitro maturation: control, cultured only in maturation base medium (TCM 199+); or supplemented with DMSO; DXR; A. oncocalyx or onco A. After in vitro maturation, oocyte chromatin configuration and viability were assessed. After 7 days of culture, there was a reduction (P < 0.05) in the percentage of morphologically intact follicles, antrum formation, growth rate and number of PCNA positive granulosa cells in DXR treatment compared to the other treatments. In the DXR treatment a higher percentage (P < 0.05) of TUNEL positive follicles and higher (P < 0.05) relative BAX:BCL2 mRNA ratio’s were observed. After in vitro maturation of the COCs DXR, A. oncocalyx and onco A treatments had a greater (P < 0.05) percentage of abnormal oocytes and a lower (P < 0.05) percentage of viable oocytes as compared with the control group. However, only DXR and onco A treatments increased (P < 0.05) the percentage of alive oocytes with abnormal chromatin configuration. There were no differences in maturation rates between the control group and DXR, A. oncocalyx and onco A treatments. In conclusion, under our culture conditions, A. oncocalyx and onco A do not exhibit a toxic effect on isolated secondary follicles and on maturation rates of COCs recovered from antral follicles, however, these drugs negatively affected the COCs viability.  Thus, the use of culture biotechnologies as an in vitro secondary follicle culture and in vitro oocyte maturation toxicity testing are appropriated methods to evaluate the possible effects of drugs in folliculogesis.

scholarly journals Acclimatization and Growth of Dwarf Pampas Grass in Response to Fertilizer Application Following In Vitro Culture

1993 ◽  
Vol 11 (1) ◽  
pp. 20-22
Author(s):  
C.D. Robacker
Keyword(s):  
Growth Rate ◽  
In Vitro Culture ◽  
Rapid Growth ◽  
Rate Increase ◽  
Fertilizer Application ◽  
Fresh Weight ◽  
Liquid Fertilizer ◽  
Soluble Fertilizer ◽  
Cortaderia Selloana

Abstract Dwarf pampas grass (Cortaderia selloana Schult. ‘Pumila’) plantlets produced in vitro were subjected to one of seven fertilization treatments during acclimatization to greenhouse conditions. Though all plantlets survived acclimatization, level of fertilizer significantly affected growth rate. Increase in fresh weight, leaf number and tillering during the first 6 weeks of acclimatization was greater when Osmocote micro-fertilizer at 2 kg/m3 (oz/ft3) was incorporated into the growing mix (Pro-Gro 200 with starter nutrients) as compared to 4 kg/m3 (oz/ft3) of Osmocote or addition of liquid fertilizer. The slowest growth was obtained from plants growing without Osmocote or liquid fertilizer. Once adapted to the greenhouse, plants fertilized with 400 mg/1 (ppm) N from 17N-4P-11K (17-9-13) soluble fertilizer twice per week had the most rapid growth.

scholarly journals Développement D’un Stock De Semences (Seedstocks) De L’algue Rouge Gelidium Corneum (Gelidiaceae, Rhodophyta)

2018 ◽  
Vol 14 (6) ◽  
pp. 112
Author(s):  
Houda Chiheb ◽  
Pilar García-Jiménez ◽  
Rafael R. Robaina ◽  
Mustapha Hassoun ◽  
Hassane Riadi
Keyword(s):  
Growth Rate ◽  
Endangered Species ◽  
In Vitro Culture ◽  
Growth Regulator ◽  
Red Algae ◽  
Artificial Seawater ◽  
Rhizoid Formation ◽  
Seawater Medium

Gelidium corneum is a species of red algae notable for its commercial important as an agarophyte in Morocco. Several regions from the Moroccan Atlantic show that this alga is an endangered species due to the excessive tearing. Hence, the repopulation of these areas is necessary. The in vitro culture of the species was carried out in three media: enriched seawater medium (PES medium (Provasoli Enriched Seawater, Provasoli 1968)), medium with seawater (SW) and medium with artificial seawater, with the addition of polyamines (putrescine (put), spermidine (spd), and spermine (spr)) as a growth regulator in the three media. The results obtained are very significant, especially in PES medium with a growth rate of 95%. Rhizoid formation and attachment of explants have been noted, especially in PES + Put medium.

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