麦片分析：影响烹饪质量的全麦特性与蛋白质矿物质比较

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宏观阵列分析是一种在食品工业尤其是面食领域中的重要工具，其核心是通过精细研磨（如将小麦磨成粗粒状的Semolina）来提升产品的特性。Durum小麦是这种分析的关键成分，它富含蛋白质和矿物质，这些特性使其特别适合用于制作出口感优良的意大利面。相比之下，软质小麦则不常用于食品生产，主要因为其营养成分和烹饪性能的不同。在Microarray技术中，M代表着缩写，可能指的是细胞分裂（mitosis）的平均值或者统计学中的均值概念。例如，M9细菌基本培养基是一种用于细菌生长的浓缩盐溶液，含有特定比例的化学物质，如Na2HPO4、KH2PO4等，以及补充氨基酸的选项。这表明宏观阵列分析也涉及到生物学实验中对微生物培养基的选择和优化。另一个关键词"MComponent"与Paraprotein有关，可能是蛋白质组学研究中的术语，表示某个蛋白质复合体的组成部分。Cytotype提及的是杂交体的形成过程，如在遗传工程或细胞融合实验中可能用到的技术。 M13噬菌体是一个重要的工具，特别是在DNA序列测定中，因其能携带和释放DNA片段，便于分子生物学研究。MPhase指的是细胞周期中的一个阶段，即有丝分裂和减数分裂时期，这个阶段的特征包括染色体结构可见和核分裂完成。 Phase Histone-1 Kinase是一种与细胞生长相关的激酶，它在细胞周期调控中扮演着关键角色。MPF，即成熟促进因子，实际上是同一个概念，负责驱动细胞从一个生命周期阶段过渡到下一个。 RNA的提及可能是指特定病毒，如 Cowpea Mosaic Virus (CPMV)，它是一种在植物中传播的病毒，可能导致病害。MVirus则指代具有致病性的病毒株，这些病毒可能对生物体造成损害。在地质时间尺度上，Ma（Millennium Annum）代表千年的单位，而在免疫学中，MaAb特指单克隆抗体，是由单一B细胞克隆产生的高度特异性的抗体。Mab则是小鼠抗体的通用术语。最后，MAC（Mammalian Artificial Chromosome）指的是哺乳动物人工染色体，这是一种科研工具，用于基因转移和遗传改造，包括HAC（Human Artificial Chromosome）、HAEC（Human Altered Endogenous Chromosome）、YAC（Yeast Artificial Chromosome）、BAC（Bacterial Artificial Chromosome）、PAC（Pooled Artificial Chromosome）和SATAC（Synthetic Apoptotic Tumor Necrosis Factor-inducing Chromosome）等多种形式。在免疫学文献中引用的Grimes和Cooke（1998）的研究进一步揭示了MAC在人类基因组研究中的应用。宏观阵列分析不仅关注食品加工中的小麦品种选择，还涉及微生物培养、细胞生物学、基因操作等多个生物学领域的关键技术及其应用。

Mantle Cell Lymphoma (MCL, human translocation

[11;14][q13;q32] or mutation at 11q22-q23): A non-

Hodgkin type lymphoma. Derived from naïve CD5

B cells of the primary follicles or of the mantle zones

of the secondary follicles. The segment deleted from

chromosome 11q22-q23 includes the ataxia telangi-

ectasia locus. The translocation juxtaposes cyclin D1

(CCND1) and the transcriptional control element of

the immunoglobulin G gene although other factors

(c-Myc) are also required for the development of

the lymphoma. ▶anaplastic lymphoma, ▶ataxia

telangiectasia

Manx Cat: Tailless, because of fusion, asymmetry and

reduction in size of one one or more caudal vertebrae

(see Fig. M16). A dominant gene that is lethal in

homozygotes causes this phenotype. The Manx

protein is essential also for the development of the

notochord of lower animals. ▶brachyury, ▶notochord

Figure M16. Caudal end of Manx cat

MAO (monoamine oxidase): This enzyme is involved

in the biosynthetic path of neurotransmitters from

amino acids. Mutation in the 8th exon (amino acid

position 936) converted the glutamine codon CAG to

TAG (chain termination codon) and resulted in mild

mental retardation, continued and impulsive aggres-

sion, arson, attempted rape, and exhibitionism in

human males with this X-chromosomal recessive

defect. The block of MAOA resulted in accumulation

of normetanephrine (a derivative of the adrenal

hormone epinephrine), and tyramine (an adrenergic

decarboxylation product of tyrosine) and a decrease

in 5-hydroxyindole-3-acetone. The heterozygous

women were not affected behaviorally or metaboli-

cally; monoamine oxidase B level remained normal.

Both enzymes are in human chromosome Xp11.2-

p11.4 and the enzymes are located in the mitochon-

drial membrane. The enzymes may affect various

psychiatric disorders such as the Gilles de la Tourette

syndrome, panic disorder, alcoholism, etc. ▶mito-

chondria, ▶Norrie disease, ▶Tourette syndrome

MAP: see Microtubule associated proteins. ▶ASE1,

▶microtubule, ▶centrosome, ▶map genetic

MAP (multi-use affinity probe): A biarsenic tag of

amino acids in proteins facilitating easy monitoring

interactions (Cao H et al 2007 J Amer Chem Soc 129:

12123).

MAP-1 (modulator of apoptosis): A mitochondria-

associated protein and activates BAX when it is

translocated into the mitochondria from the cytosol

upon apoptotic signals. RNAi regulates MAP-1.

▶apoptosis, ▶BAX, ▶RNAi; Tan KO et al 2005

Proc Natl Acad Sci USA 102:14623.

MAP-Based Cloning (positional cloning): Isolation of

gene(s) on the basis of chromosome walking and

propagation usually by YAC and/or cosmid clones.

After a genome sequence has been completed,

positional cloning will no longer be needed as long

as the function of the gene is also known. Positional

cloning may be complicated by the fact that some

phenotypes are affected by more than a single locus.

▶chromosome walking, ▶chromosome landing, ▶po-

sition effect; Lukowitz W et al 2000 Plant Physiol

123:795; Tanksley SD 1995 Trends Genet 11:63.

MAP Distance: Indicates how far syntenic genes are

located from each other in the chromosome as

estimated by their frequency of recombination; 1 map

unit = 1% recombination = 1 centi Morgan. The

greater the distance between two genes, the higher is

the chance that they are separated by recombination.

A single recombination between two genes in a

meiocyte produces maximally 50% recombination

that is 50 map units. The distance between syntenic

genes may exceed 50 map units several times; these

longer distances are determined then in a staggered

manner, proceeding step-wise from left to right and

right to left. In prokaryotes, using conjugational

transfer and recombination, map distances are

measured in minutes of transfer. ▶conjugational

mapping, ▶recombination frequency, ▶radiation

hybrids, ▶mapping function

MAP Expansion: The distance between two distant

markers exceeds the sum of the distances of markers

in between; it is commonly observed in gene

conversion. ▶gene conversion; Holliday R 1968

p 157. In: Replication and Recombination of Genetic

Material. Peacock WJ, Brock RD (Eds.) Australian

Acad Sci, Canberra.

Map, Genetic: The order of genes (markers) in

chromosomes determined on the basis of recombina-

tion frequencies. ▶mapping, ▶recombination fre-

quencies, ▶physical map, ▶radiation hybrids

▶RFLP, ▶RAPD, ▶mapping function; Human genes:

OMIM; http://linkage.rockefeller.edu/; genetic &

physical of various organisms: http://www.ncbi.nlm.

nih.gov/Genomes/index.html.

1150 Mantle Cell Lymphoma

Map Genetic Versus Physical Map: ▶coefficient of

crossing-over, ▶gene number; Ashburner M et al

1999 Genetics 153:179.

Map Kinase (MPK): A family of serine/threonine

protein kinases associated with mitogen activation

(growth) and stress responses. Three groups exist:

ERK, cJun N-terminal kinase (JNK) and p38. These

paths of responses interact at various levels. They

have a key role in signal transduction pathways. The

p42 and p44 MPKs are also called ERK2 and ERK1,

respectively. The MAP kinase family is activated by

STE20, RAS, Raf protein serine/threonine kinases. In

normal T cells, T cell receptor and CD28 synergisti-

cally activate p38. An alternative activation pathway

involves Tyr323 by antigen-stimulated T cells but not

B cells (Salvador JM et al Nature Immunol 6:390).

MAPK81P1 (11p11.2-p12) may be a transactivator of

SLC2A2 gene encoding GLUT2 glucose transporter

and one of the factors responsible for MODY

diabetes. The MAP kinases follow the signaling

path: MAPKKK → MAPKK → MAPK. ▶cell cycle,

▶signal transduction, ▶MAPK, ▶JNK/SAPK,

▶ERK, ▶p38, ▶STE diabetes, ▶MODY, ▶GLUT;

Cobb MH 1999 Progr Biophys Mol Biol 71:479;

English J et al 1999 Exp Cell Res 253:255; Chang L,

Karin M 2001 Nature [Lond] 410:37; Dong C et al

2002 Annu Rev Immunol 20:55; Park S-H et al 2003

Science 299:1061; Schwartz MA, Madhani HD 2004

Annu Rev Genet 38:725.

MAP Kinase Kinase (MAPKK): ▶Ste 7

MAP Kinase Kinase Kinase (MAPKKK): ▶Ste 11

MAP Kinase Kinase Kinase Kinase (MAPKKKK):

▶Ste 20

MAP KINASE PHOSPHATASE (MPK): MPK-3 depho-

sphorylates phosphotyrosine and phosphothreonine

and inactivates the MAP kinase family proteins.

Binding activates it by its non-catalytic C-end to

ERK2 without a need for phosphorylation. The

homologous MPK-4 is also activated by ERK2 but

also by JNK/SAPK and p38. ▶signal transduction

and other proteins under separate entries; Zhang T

et al 2001 Gene 273:71.

Map Manager v 2.5: The software for storing, organizing

genetic recombination data and data base for RI strains

of mouse. Information: K.F. Manly, Roswell Park

Cancer Institute, Elm & Carlton, Buffalo, NY 14263,

USA. Phone: 716–845–3372. Fax: 716–845–8169.

kmanly@mcbio.med.buffalo.edu.

Map, Metric: An on-scale ordered FISH map where

cosmid clones can orderly be positioned. ▶FISH,

▶cosmid

Map, Physical: ▶physical map

Map, Self-Organizing: Constructed on the basis of

mathematical cluster analysis; recognizes and classi-

fies complex multidimensional data such as informa-

tion of an array of genes involved in differentiation or

other complex pathways. ▶cluster analysis

Map Unit: 1% recombination = 1 map unit (m.u. or

1 centiMorgan, c.m. or cM). In approximate kilobase

pairs equivalent to one centiMorgans in a few species:

Arabidopsis ≈

140; tomato ≈ 510; human ≈ 1,108 (in

human chromosome 10 the recombination frequency

is 1.32 cM/Mb

−1

); maize ≈ 2,140. The Salamanders

have the largest known genetic map 7291 cM.

▶recombination frequency

Map Viewer: Provides genomic information by chromo-

somal location of a variety of eukaryotic organisms

from animals to plants, fungi and protozoa. It can be

queried by gene name, sequence alignment (BLAST),

etc. ▶genome, ▶BLAST; http://www.ncbi.nlm.nih.

gov/mapview/.

MAPCS (multipotent adult progenitor cells): These are

“universal stem cells” present in small numbers in

some adult tissues and have the capacity to produce

other types of cells in a manner similar to embryonic

stem cells. ▶stem cells; Jiang Y et al 2002 Nature

[Lond] 418:41; Schwartz RE et al 2002 J Clin Invest

109:1291.

MAPK (mitogen-activated protein kinase): Distinct

kinases responding to different environmental cues

and sets into motion different development/physio-

logical pathways. The family includes KSS1 (fila-

mentous growth), HOG-1 (hypertonic stress), FUS3

(mating), Mpk1 (cell wall remodeling), SLT-2, sapk-1

(stress activated protein kinase), FRS (FOS regulat-

ing kinase), erk-1 (extracellular signal regulated

kinase), Smk1 (sporulation), etc. In yeast association

with the Ste12 transcriptional activator regulates the

specificity. Ste12 in combination with other proteins

may bind to the pheromone response element (PRE).

Ste12 protein associates with the filamentation

and invasion response element (FRES), including A

Ste12 protein binding site (TGAAACA) and a

neighboring CATTCY sequences specific for the

Tec1 (non-receptor tyrosine kinase) transcription

factor. The mating and filamentous growth pathways

are initiated in a similar way but for mating the FUS

kinase is activated rather than the KSS. In the absence

of phosphorylation KSS inhibits the Ste12-Tec1

complex and filamentous growth. The Dig proteins

appear to be cofactors of the inhibitory path. In the

inhibitory MAPKs (KSS), there is the MKI (MAP

kinase insertion) site, which is remodeled upon

phosphorylation and thus conversion into an activa-

tor. The specificity of the MAPKs is secured also by

the complexes of recruited proteins, and each of these

MAPK 1151

selects the appropriate MAPK. ▶signal transduction,

▶MAPKK, ▶MEK, ▶arrestin, ▶Ask, ▶JNJ FOS,

▶Ste, ▶anthrax; Ito M et al 1999 Mol Cell Biol

190:7539; Roberts CJ et al 2000 Science 287:873;

Pouysségur J 2000 Science 290:1515; Barsyte-

Lovejoy D et al 2002 J Biol Chem 277:9896.

MAPKK (mitogen-activated [MAP] protein kinase ki-

nase): This protein mediates signal transduction path-

ways by phosphorylating RAS, Src, Raf and MOS

oncogenes. When such an active kinase was intro-

duced into mammalian cells, the AP-1 transcription

factor was activated and the cells formed cancerous

foci and became highly tumorigenic in nude mice,

indicating that MAPKK is sufficient for tumorigenesis.

▶signal transduction, ▶tumor, ▶anthrax, ▶NPK

MAPKKK: Mitogen activated protein kinase kinase

kinase. ▶TAK1

Maple (Acer spp.): Hardwood trees; sugar maple is used

for collecting syrup, 2n = 26.

Maple Syrup Urine Disease: ▶isoleucine-valine biosyn-

thetic pathway

Mapmaker 3.0: A software for constructing linkage

maps using multipoint analysis in testcross and F

MAPMAKER/QTL is for quantitative trait loci.

Available for Sun (Unix), PC (DOS) and Macintosh.

Contact: Eric Lander, Whitehead Institute, 9

Cambridge Center, Cambridge, MA 02142, USA.

Fax: 617–258–6505. INTERNET: mapmaker@

genome.wi.mit.edu.

Mapping: Establishes the sequential location of genes,

restriction fragments or PCR products. Molecular

mapping of individual genomic DNA molecules

labeled with fluorescent dyes at specific sequence

motifs by the action of nicking endonuclease

followed by the incorporation of dye terminators

with DNA polymerase can be used. The labeled DNA

molecules are then stretched into linear form on a

modified glass surface and imaged using total internal

reflection fluorescence (TIRF) microscopy. By deter-

mining the positions of the fluorescent labels with

respect to the DNA backbone, the distribution of the

sequence motif recognized by the nicking endonu-

clease can be established with good accuracy in a

manner similar to reading a barcode (Xiao M et al

2007 Nucleic Acids Res 35(3):e16). ▶genome

projects, ▶physical maps, ▶recombination, ▶restric-

tion endonuclease, ▶PCR, ▶SNIPs, ▶radiation

hybrids, ▶databases; http://linkage.rockefeller.edu/.

Mapping by Admixture Linkage Disequilibrium:

▶MALD

Mapping by Dosage Effect: If the activity of enzymes is

proportional to their dosage and disomics can be

distinguished from critical trisomics, genes (for the

enzymes) located in a specific trisome can be

identified and assigned to that specific chromosome

or in the case of telotrisomic to a particular

chromosome arm. Theoretically, the enzyme activity

is expected as follows if the locus is situated in the

long arm of a particular chromosome (see Fig. M17).

In human trisomy 21 several genes show increased

expression ranging from 1.21 to 1.61 relative to the

normal disomic condition. Thus, in practice, the

dosage effect may not be perfectly additive, yet it may

be clear enough for classification. ▶trisomics;

Carlson PS 1972 Mol Gen Genet 114:273.

Mapping, Genetic: The mapping of chromosomes

can be carried out on the basis of recombination

frequencies of chromosomal markers, either genes or

DNA markers such as RFLPs, RAPDs, etc., or

molecular methods used in physical mapping (chromo-

some walking). As a hypothetical example assuming

that genes a, b, c, d and e are syntenic, the recombina-

tion frequencies between them was found to be:

a 0.06 b 0.04 c 0.06 d 0.16 e 0.18 g

The sum of the recombination frequencies is 0.06 +

0.04 + 0.06 + 0.16 + 0.18 = 0.50 indicating that the

segregation between a andg isindependent.Theresults

shown could be obtained between two genes at a time

butsucha two-pointcrosswouldnot havepermittedthe

determination of the order of the genes relative to each

other. For the determinationofgenes at “left” and genes

at “right” a three-point cross is required as a minimum,

and multipoint crosses are even more helpful ▶

recom-

bination frequencies. For the results of a hypothetical

three-point testcross see Table M2.

According to the data, the number of recombinants

in interval I was 10 + 2 and in interval II 20 + 2 (the

double recombinants had recombination in both

interval I and II and their number must be added to

the numbers observed). Thus the frequency of

23 2 3 4

Figure M17. Mapping by dosage effects

1152 MAPKK

recombination between A and B is 12/100 = 0.12 and

between B and D 22/100 = 0.22. The number of

recombinations between A and D is 10 + 20 + 4 = 34

(the 4 is the double of the number of recombinants in

intervals I and II because these represented double

recombination events).

Thus the relative map positions are A − B − D. Had

it been found that the combined parental numbers

were 68 but the recombinants Abd plus aBD 10 and

ABd plus abD 2, and AbD plus aBd 20, it had to be

concluded that the gene order was A − D − B, because

the lowest frequency class (0.10 × 0.20 = 0.02) must

have been the double recombinants, and thus the gene

order would have been A – D – B. The observed

recombination frequencies may have to be corrected

by mapping functions because not all double-

crossovers might have been detected (see Mapping

functions). The recombination frequencies may be

biased also by interference when the frequency of

double-crossovers are either higher or lower than

expected on the basis of the product of the two

single-crossovers (see ▶Coincidence, Interference).

The (corrected) recombination frequencies can be

converted to map units by multplication with 100 and

1 map unit (m.u. or centiMorgan [cM]) is 0.01

frequency of recombination. Recombination frequen-

cies can be estimated also in F

by using the product

ratio method (see ▶Product ratio method). In the

latter case recombination frequencies can be calcu-

lated only between pairs of loci yet from the data of

two pairs involving 3 loci, the gene order can be

determined. On the basis of SNIPs human linkage

maps of 3.9 cM resolution have been generated

(Matise TC et al 2003 Am J Hum Genet 73:271).

Availability of complete nucleotide sequences of the

genomes does not obviate the calculations of

recombination frequencies because the physical maps

and the genetic map lengths are not necessarily

identical. ▶Recombination frequencies, ▶crossing

over, ▶QTL, ▶deletion mapping, ▶chromosome

walking, ▶physical maps, ▶mapmaker, ▶joinmap,

▶maximum likelihood method applied to recombi-

nation, ▶mapping functions, ▶radiation hybrids,

▶F

linkage estimation, ▶genomic screening, ▶skel-

etal map, ▶comparative map, ▶unified genetic map,

▶integrated map, ▶consensus, ▶SNIPs, ▶linkage,

▶coefficient of crossing over, ▶exclusion mapping;

Multilocus mapping algorithm for humans: Lander

ES, Green P 1987 Proc Natl Acad Sci USA 84:2363;

Ott J, Hoh J 2000 Am J Hum Genet 67:289; Grupe A

et al 2001 Science 292:1915; survey of newer

multipoint algorithms: Gudbjartsson DF et al 2005

Nature Genet 37:1015.

Mapping Functions: Correct map-distance estimates

from recombination frequencies when the recombi-

nation frequency in an interval exceeds 15–20% and

double crossing overs are undetectable because

of the lack of more densely positioned markers.

▶Haldane’s mapping function, ▶Kosambi’s mapp-

ing function, ▶Carter-Falconer mapping function,

▶mapping, ▶recombination frequency, ▶coefficient

of coincidence, ▶stationary renewal process,

▶count-location models; Zhao H, Speed TP 1996

Genetics 142:1369.

Mapping in Silico: Feeding phenotypic information to a

computer program facilitates fast information

gathering on the regulation and chromosomal loca-

tions of the multiple factors involved in a polygenic

disease. ▶polygenic; Grupe A et al 2001 Science

292:1814.

Mapping Panels: These are DNA sequences with

known chromosomal location and can be used to

locate unknown sequences to chromosomes. ▶radia-

tion hybrid panels

Mapping Sets: ▶genomic screening

MapSearch: Locates regions of a genomic restriction

map that resemble best a local restriction the so-

called probe.

MapShow: A computer program displaying MapSearch

alignments and draws Probe-to-Map alignments in

Sun Workstations. ▶mapping

MAR (matrix attachment region): Attaches chromatin

loops to the nuclear matrix. The attachment region has

a consensus of so-called A box (AATAAATCAA) or a

T box (TTA/TAA/TTTA/TTT). The MARs are about

100 to 1,000 bp long and frequently include replica-

tional origins and transcription factor binding

sites. ▶chromatin, ▶loop domains mode, ▶scaffold;

Stratling WH, Yu F 1999 Crit Rev Eukaryot Gene Expr

Table M2. A hypothetical three-point testcross

Phenotypic classes → ABD abd Abd aBD ABd abD AbD aBd

Number of individuals 34 34

|ﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄ{zﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄ}

10 10

|ﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄ{zﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄﬄ}

Parental Recombinants

interval I

Recombinants

interval II

Recombinants

intervals I + II

Total of 100 68 10 20 2

MAR 1153

9(3–4):311; Pemov A et al 1998 Proc Natl Acad Sci

USA 95:14757; http://www.futuresoft.org/MAR-Wiz.

Maranhar: ▶killer plasmids, ▶Neurospora

Marburg Virus: A negative-sense single-stranded RNA

virus containing seven genes within a lipid envelope

(see Fig. M18). Besides transcribing its full genome,

it produces subgenomic RNAs without encapsidation

and these can also be translated into viral protein. The

name comes from the German city Marburg where it

was discovered in 1967 in monkeys shipped from

Uganda. The virus causes hemorrhagic fever and very

high mortality. Current efforts are directed to the

development of efficient vaccine and RNAi based

defense systems. ▶Ebola virus, ▶RNAi, ▶vaccines;

Fowler T et al 2005 J Gen Virol 86:1181.

Figure M18. Marburg virus

MARCKS (myristoylated alanine-rich C kinase sub-

strate): Protein substrates of the protein kinase C

(PKC), involved in differentiation; they bind actin

filaments. (See Spizz G, Blackshear PJ 2001 J Biol

Chem 276:32264).

mardel10: A supernumerary human chromosome 10

with a large deletion at the regular centromere. The

deletion, however, activates, a functional neocentro-

mere at 10q25, which lacks α-satellite and CENP-B

centromeric protein although it shows some other

centromere proteins. ▶centromere, ▶neocentromere,

▶human artificial chromosome; Voullaire LE et al

1993 Am J Hum Genet 52:1153; Choo KH A 1997

Am J Hum Genet 61:1225.

Marek’s Disease: A lymphoproliferative viral chicken

disease. The growth hormone, GH1 conveys resis-

tance. ▶herpes, ▶Epstein-Barr virus ; Liu H-C et al

2001 Proc Natl acad Sci USA 98:9203; Levy AM

et al 2005 Proc Natl Acad Sci USA 102:14831.

Marfan Syndrome (MFS, FBN1): Common symptoms

include tall thin stature, long limbs and fingers, chest

deformations. The three most consistent defects are

skeletal, heart-vein (cardiovascular) and eye (ectopia

lentis) abnormalities. The disease may affect the

development of the fetus and may be recognized in

early development and the life expectancy in serious

cases may not much exceed 30. The cause of death is

generally heart failure but the defect may be surgically

corrected in some cases. The penetrance appears very

good but the expressivity is highly variable. The

symptoms frequently overlap with other anomalies,

particularly with those of the Ehlers-Dunlop syndrome.

The latter involves a defect in collagen. The primary

defect in MFS involves the elastic fiber system

glycoprotein, fibrillin. This protein of the connective

tissue contains repeats resembling sequences in the

epidermal growth factor (EGF) where the lesion

observed leads to the identification of the basic

molecular cause. Formerly a collagen defect was

suspected.

Several investigators confirmed a transversion

mutation at codon 293 leading to CGC (Arg) →

CCC (Pro) replacement. Similar molecular defects

have been identified in Drosophila, Caenorhabditis

and cattle. This dominant gene has been assigned to

human chromosome 15q21.1. Interestingly, mosai-

cism for trisomy 8 causes similar symptoms. The

prevalence of MFS/FBN1 is about 1 × 10

−4

but this

figure may not be entirely reliable because of the wide

range of manifestation of the symptoms (seeFig. M19).

The recurrence risk is about 50%; 15–30% of the

cases may be due to new mutation that is the cause of

the most severe cases, whereas the familial incidence

generally entails milder symptoms. The estimated

mutation rate is 4 − 5×10

−6

. FBN1 may be dominant

negative. The mutation in fibrillin-1 affects the

regulation of transforming growth factor (TGF-β)

resulting in apoptosis of the alveolar cells of the lung.

Excessive signaling of TGF-β family cytokines can

cause aortic aneurysm in mice and can be blocked by

angiotensin II type1 receptor blocker drug, Losartan

(Habashi JP et al 2006 Science 312:117).

Figure M19. Marfan syndrome. (Courtesy of Dr. D.L.

Rimoin, Los Angeles)

A higher probability of ectopia lentis was found for

patients with a missense mutation substituting or

producing a cysteine, when compared with other

1154 Maranhar

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麦片分析：影响烹饪质量的全麦特性与蛋白质矿物质比较

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