The processing methods of plant nematode slides were introduced in this paper,including temporary mounts,permanent mounts and the stain method for nematode.Each method was described step by step in detail.These methods were essential to the study on classification,identification and characteristics of the plant nematode.

Classification of plant nematodes was summarized in this paper.Points of view on taxonomy of plant nematodes were listed.Some serious plant diseases which were infected by plant nematodes were involved.Identification of genus was introduced,including Meloidogyne,Heterodera,Ditylenchus,Aphelenchoides and Bursaphelenchus.

OBJECTIVETo explore the role of the mutation of presenilin-1 exon 6 in pathogenesis of Alzheimer's disease(AD) patients.

METHODSExon 6 of presenilin-1 was analyzed by use of polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA analyzer technique in 2 patients with familial AD, 53 patients with sporadic DA, 60 patients with vascular dementia(VD) and 90 normal controls.

RESULTSMobility shift of SSCP in exon 6 of presenilin-1 was detected in 2 cases with FAD, 4 cases with SDA and 1 case with VD. Two missense mutations were found in the patients by DNA sequence analysis, one mutation was 1123 nt C-->G(Cys 23 Trp) and the other was 1300 nt A-->C(Asp 200 Ala).

CONCLUSIONMutations in exon 6 of presenilin-1 existed in the patients with FAD and SDA, and the two missense mutations were probably pathological by nature.

Aged ; Aged, 80 and over ; Alzheimer Disease ; genetics ; Exons ; genetics ; Female ; Humans ; Male ; Mutation ; Mutation, Missense ; Pedigree ; Polymerase Chain Reaction ; Polymorphism, Single-Stranded Conformational ; Presenilin-1 ; genetics ; Sequence Analysis, DNA