Unidirectional dominance of cytoplasmic inheritance in two genetic crosses of Plasmodium falciparum

1993 ◽  
Vol 13 (12) ◽  
pp. 7349-7357
Author(s):  
A B Vaidya ◽  
J Morrisey ◽  
C V Plowe ◽  
D C Kaslow ◽  
T E Wellems
Keyword(s):  
Plasmodium Falciparum ◽  
Single Strand Conformation Polymorphism ◽  
Cytoplasmic Inheritance ◽  
Polymorphism Analysis ◽  
Inheritance Pattern ◽  
Dna Molecules ◽  
Genetic Crosses ◽  
Male Gametes ◽  
Cytoplasmic Dna ◽  
Geographical Regions

Malarial parasites have two highly conserved cytoplasmic DNA molecules: a 6-kb tandemly arrayed DNA that has characteristics of a mitochondrial genome, and a 35-kb circular DNA that encodes functions commonly found in chloroplasts. We examined the inheritance pattern of these elements in two genetic crosses of Plasmodium falciparum clones. Parent-specific oligonucleotide probes and single-strand conformation polymorphism analysis identified single nucleotide changes that distinguished the parental 6- and 35-kb DNA molecules in the progeny. In all 16 independent recombinant progeny of a cross between a Central American clone, HB3, and a Southeast Asian clone, Dd2, the 6- and 35-kb DNAs were inherited from the Dd2 parent. In all nine independent recombinant progeny of a cross between clone HB3 and a likely African clone, 3D7, the 6-kb DNA was inherited from the 3D7 parent. Inheritance of cytoplasmic genomes of the Dd2 and 3D7 parents was, therefore, dominant over that of the HB3 parent. Cytoplasmic DNA molecules were found almost exclusively in the female gametes of malarial parasites; hence, clone HB3 did not appear to have served as a maternal parent for the progeny of two crosses. Defective differentiation into male gametes by clone Dd2 is likely to be a reason for the cytoplasmic inheritance pattern seen in the HB3 x Dd2 cross. However, incompetence of male or female gametes is unlikely to explain the uniparental dominance in recombinant progeny of the HB3 x 3D7 cross, since both parents readily self-fertilized and completed the malaria life cycle on their own. Instead, the data suggest unidirectional parental incompatibility in cross-fertilization of these malarial parasites, where a usually cosexual parental clone can participate only as a male or as a female. Such an incompatibility may be speculated as indicating an early phase of reproductive isolation of P. falciparum clones from different geographical regions.

scholarly journals Unidirectional dominance of cytoplasmic inheritance in two genetic crosses of Plasmodium falciparum.

1993 ◽  
Vol 13 (12) ◽  
pp. 7349-7357 ◽  
Author(s):  
A B Vaidya ◽  
J Morrisey ◽  
C V Plowe ◽  
D C Kaslow ◽  
T E Wellems
Keyword(s):  
Plasmodium Falciparum ◽  
Single Strand Conformation Polymorphism ◽  
Cytoplasmic Inheritance ◽  
Polymorphism Analysis ◽  
Inheritance Pattern ◽  
Dna Molecules ◽  
Genetic Crosses ◽  
Male Gametes ◽  
Cytoplasmic Dna ◽  
Geographical Regions

Malarial parasites have two highly conserved cytoplasmic DNA molecules: a 6-kb tandemly arrayed DNA that has characteristics of a mitochondrial genome, and a 35-kb circular DNA that encodes functions commonly found in chloroplasts. We examined the inheritance pattern of these elements in two genetic crosses of Plasmodium falciparum clones. Parent-specific oligonucleotide probes and single-strand conformation polymorphism analysis identified single nucleotide changes that distinguished the parental 6- and 35-kb DNA molecules in the progeny. In all 16 independent recombinant progeny of a cross between a Central American clone, HB3, and a Southeast Asian clone, Dd2, the 6- and 35-kb DNAs were inherited from the Dd2 parent. In all nine independent recombinant progeny of a cross between clone HB3 and a likely African clone, 3D7, the 6-kb DNA was inherited from the 3D7 parent. Inheritance of cytoplasmic genomes of the Dd2 and 3D7 parents was, therefore, dominant over that of the HB3 parent. Cytoplasmic DNA molecules were found almost exclusively in the female gametes of malarial parasites; hence, clone HB3 did not appear to have served as a maternal parent for the progeny of two crosses. Defective differentiation into male gametes by clone Dd2 is likely to be a reason for the cytoplasmic inheritance pattern seen in the HB3 x Dd2 cross. However, incompetence of male or female gametes is unlikely to explain the uniparental dominance in recombinant progeny of the HB3 x 3D7 cross, since both parents readily self-fertilized and completed the malaria life cycle on their own. Instead, the data suggest unidirectional parental incompatibility in cross-fertilization of these malarial parasites, where a usually cosexual parental clone can participate only as a male or as a female. Such an incompatibility may be speculated as indicating an early phase of reproductive isolation of P. falciparum clones from different geographical regions.

scholarly journals A Type II Protein Secretory Pathway Required for Levansucrase Secretion by Gluconacetobacter diazotrophicus

2004 ◽  
Vol 186 (15) ◽  
pp. 5031-5039 ◽  
Author(s):  
Juan G. Arrieta ◽  
Mailin Sotolongo ◽  
Carmen Menéndez ◽  
Dubiel Alfonso ◽  
Luis E. Trujillo ◽  
...  
Keyword(s):  
Codon Usage ◽  
Outer Membrane ◽  
Gene Cluster ◽  
Secretory Pathway ◽  
Cosmid Library ◽  
Polymorphism Analysis ◽  
Type Ii ◽  
Gluconacetobacter Diazotrophicus ◽  
Type Iv ◽  
Geographical Regions

ABSTRACT The endophytic diazotroph Gluconacetobacter diazotrophicus secretes a constitutively expressed levansucrase (LsdA, EC 2.4.1.10) to utilize plant sucrose. LsdA, unlike other extracellular levansucrases from gram-negative bacteria, is transported to the periplasm by a signal-peptide-dependent pathway. We identified an unusually organized gene cluster encoding at least the components LsdG, -O, -E, -F, -H, -I, -J, -L, -M, -N, and -D of a type II secretory system required for LsdA translocation across the outer membrane. Another open reading frame, designated lsdX, is located between the operon promoter and lsdG, but it was not identified in BLASTX searches of the DDBJ/EMBL/GenBank databases. The lsdX, -G, and -O genes were isolated from a cosmid library of strain SRT4 by complementation of an ethyl methanesulfonate mutant unable to transport LsdA across the outer membrane. The downstream genes lsdE, -F, -H, -I, -J, -L, -M, -N, and -D were isolated through chromosomal walking. The high G+C content (64 to 74%) and the codon usage of the genes identified are consistent with the G+C content and codon usage of the standard G. diazotrophicus structural gene. Sequence analysis of the gene cluster indicated that a polycistronic transcript is synthesized. Targeted disruption of lsdG, lsdO, or lsdF blocked LsdA secretion, and the bacterium failed to grow on sucrose. Replacement of Cys162 by Gly at the C terminus of the pseudopilin LsdG abolished the protein functionality, suggesting that there is a relationship with type IV pilins. Restriction fragment length polymorphism analysis revealed conservation of the type II secretion operon downstream of the levansucrase-levanase (lsdA-lsdB) locus in 14 G. diazotrophicus strains representing 11 genotypes recovered from four different host plants in diverse geographical regions. To our knowledge, this is the first report of a type II pathway for protein secretion in the Acetobacteraceae.

Novel Method for Simultaneous Analysis of p53 and K-ras Mutations and p53 Protein Expression in Single Histologic Sections

2001 ◽  
Vol 125 (3) ◽  
pp. 347-352
Author(s):  
Kazuya Yamashita ◽  
Tsutomu Yoshida ◽  
Hiroshi Shinoda ◽  
Isao Okayasu
Keyword(s):  
Polymerase Chain Reaction ◽  
Protein Expression ◽  
P53 Protein ◽  
Single Strand Conformation Polymorphism ◽  
Antigen Retrieval ◽  
Cancer Tissue ◽  
Polymorphism Analysis ◽  
Chain Reaction ◽  
Novel Method ◽  
Polymerase Chain

Abstract Background and Objective.—Abnormal protein expression and gene mutation should be examined on exactly identified lesions. To perform simultaneous analyses of oncogene or tumor suppressor gene mutations and related protein expression in single histologic sections, we have developed a novel method using an antigen-retrieval solution for a polymerase chain reaction template before immunohistochemical staining. Methods.—Using 20 cases of sporadic colorectal carcinoma, several kinds of antigen-retrieval solutions were tested after heating rehydrated, 4-μm-thick, formalin-fixed, paraffin-embedded histologic sections at 96°C for 20 minutes. Polymerase chain reaction–single-strand conformation polymorphism analysis was conducted for p53 (exons 5 through 9) and K-ras (exons 1 and 2), and the histologic sections were then immunostained with monoclonal antibody against p53. Results.—DNA analysis of antigen-retrieval solutions was possible in all 20 cases and revealed completely consistent results (100%) with fresh cancer tissue and microdissected cancer tissue of paraffin-embedded histologic sections. With this method, K-ras mutations were positive in 10 of 20 cases (exon 1 in 9 cases and exon 2 in 1 case) and p53 mutations were positive in 9 of 20 cases (exon 5 in 4 cases, exon 6 in 1, exon 7 in 3, and exon 8 in 1 case), with 8 of the 9 p53 mutation cases showing diffuse p53 protein expression on immunostaining. Base alterations of all abnormal conformers were confirmed with direct sequencing. For polymerase chain reaction–single-strand conformation polymorphism analysis, sodium citrate buffer (pH 6.0) was found to be the optimal antigen-retrieval solution. Conclusions.—This newly developed method can be used for routine immunostaining and genetic analysis with single histologic sections.

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