摘要:

AbstractNew techniques have recently been described that employ the polymerase chain reaction (PCR) to amplify arbitrary regions of a genome using a single primer. The techniques reveal polymorphisms in insect taxa that lack allozyme variation and, for the first time, permit genetic polymorphisms to be rapidly analysed in small arthropods (e.g. mites, endoparasitic wasps). The methods have been used in identification of sub‐species and cryptic species, and have applications in population genetics and genetic fingerprinting. They are fairly inexpensive, do not require the use of radioactivity, are relatively simple to learn and can easily be adapted to most laboratories. However, their application is not without technical problems and practical limitations. The purpose of this note is to indicate the critical factors to consider before launching into their use. We chiefly emphasize that most polymorphisms revealed by these methods segregate as dominant markers. Furthermore, application of these techniques requires extensive standardization and may not prove to be reproducible among various laboratories especially those employing different types of thermal cyclers. There are some unique features of these polymorphisms to consider when using them in genetic fingerprinting. In addition, because the techniques amplify arbitrary regions of genomes, similarly sized fragments amplified between two species may not be homologous. This argument and empirical observations suggest that PCR with arbitrary primers will have limited application in molecular systematics above the intraspecific leve

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1993.tb00118.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA 4.1 kb genomic clone of the late trypsin gene from the mosquito Aedes aegypti was isolated, mapped and subcloned. A1.6 kb subclone, corresponding to 1.1 kb of upstream regulatory region and 0.5 kb of coding region, was sequenced. The gene has no introns within the coding region. The 5 end of the mature mRNA was mapped using primer extension analysis. A TATA box consensus sequence (TATAAA) was found at position —31 from the 5 end of the mature mRNA. A cluster of five repeat sequences homologous to the yeast GCN4 DNA binding site was found within 200 nucleotides upstream of the cap site. GCN4 is required for derepression mediated control of general amino acid biosynthesis in response to amino acid starvation in yeast. It activates the transcription of at least twenty different genes coding for enzymes involved in amino acid biosynthesis. The presence of this cluster of consensus sequences suggests that a protein similar to GCN4 might regulate expression of the late trypsin gene in the mosquito. Southern blot analysis of genomic DNA indicates that late trypsin is a single copy gen

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1993.tb00119.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractBy cDNA cloning and sequencing we have shown thatManduca sextalarvae produce three very closely related methionine‐rich storage proteins, MMR1, MMR2 and MMR3. Out of 2256 nucleotides in the coding region, the cDNAs differ by at most twenty‐one bases and this leads to a single amino acid difference between MMR1 and MMR2, and between MMR2 and MMR3, whereas MMR1 and MMR3 differ by two amino acids. Using both distance and parsimony methods, similarities between theM. sextaandBombyx morimethionine‐rich and arylphorin storage proteins were examined. Homologous proteins from the two species tend to be more closely related than are the two classes of storage proteins in a single sp

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1993.tb00120.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe two most common protocols for RNA isolation, Chirgwinet al., 1979, and Chomczynski&Sacchi, 1987, were compared with a protocol using glass powder. The quality of the recovered RNA was tested using agarose gels and Northern hybridization. With the glass powder protocol, we consistently obtained intact RNA, whereas with the other protocols we often obtained degraded RNA. Using specific radioactive probes, we measured ribosomal RNA and trypsin mRNA recovered from fed adultAedes aegyptifemales. Our protocol gave a 40‐ and a 3‐fold increase in recovery when compared with the Chirgwin and Chomczynski protocol, respectively. The method using glass powder is simple, fast, reproducible and gives a high yield of intact

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1993.tb00121.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractA cDNA(D7‐8B)1456 nucleotides in length was isolated from an adult, female‐specificAnopheles gambiaelibrary and identified as a member of the glutathione S‐transferase (GST) gene family by virtue of the inferred amino acid sequence. The gene,AgGST2‐1, specifies a protein that is 57% identical to theDrosophila melanogastergene,DmGST‐2.The conceptual translation product also shows similarity to thejtfamily of vertebrate GSTs. Northern analysis reveals multiple and abundant transcription products in larval, pupal and adult RNA preparations. Southern analyses of genomic DNA and hybridizationsin situto polytene chromosomes both suggest that there are multiple members of the GST gene family inAnophele

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1993.tb00122.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe B biotype of the sweetpotato whitefly,Bemisia tabaci(Gennadius) has caused over $200 million in crop damage in the US during 1992. The taxonomic classification of the A and B biotypes ofB. tabaciis unclear. We used RAPD‐PCR to demonstrate DNA differences between the A and B biotypes of this insect. Ail twenty of the RAPD primers tested distinguished readily between the biotypes. DNA extracted from individual eggs and nymphs showed identical differences. RAPD‐based genetic similarity statistics indicate that these two biotypes ofB. tabaciwere no more similar to each other than to two other whitefly species: bayberry whitefly(Parabemisia myri‐cae)or banded winged whitefly(Trialeurodes abutilo‐nea).These results indicate that RAPD‐PCR may be useful in distinguishing closely related organisms, but may not be useful in determining higher classification of insects. Before the taxonomic status ofB. tabacibiotypes A and B can be determined, results from other genetic, morphological and physiological examinations will have to be

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1993.tb00123.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractInDrosophilaKc cells, the 60C 03 tubulin transcription unit, whose expression is induced by 20‐hydroxy‐ecdysone (20‐OHE), has the same structure as inDrosophila.This gene is characterized by an unusual 5 intron of regulating importance, by an alternatively spliced second intron and by a long 3 transcribed but untranslated region. This gene codes for two β3 tubulin isoforms with one amino acid difference. We have established that β3 tubulin gene expression is transcriptionally regulated by the steroid hormone in a time and hormonal concentration‐dependent fashion, without requirement of protein synthesis. This implies that this transcriptional induction is a primary event and that this gene is probably a direct target for the 20‐O

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1993.tb00124.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractOnly a few prominent simple sequence repeat (SSR) loci of the type (GATA)nare found in the genome of the mealmothEphestia kuehniellaZeller. Therefore this moth was chosen as a model organism for the genetic and molecular analysis of hypervariability of SSR loci. We characterized alleles of (GATA)nloci in differentEphestiastrains by cloning and genomic restriction mapping. Some variants appeared to be mere variable number of tandem repeat (VNTR) alleles, others showed considerable changes in the sequence neighbourhood of the GATA repeats. These may be produced by major rearrangements or by transposition of the (GATA)nblock together with flanking sequences into a different sequence environment.

ISSN:0962-1075    

DOI:10.1111/j.1365-2583.1993.tb00125.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY