Furthermore, the size distribution is much narrower than when using other techniques - DNA fragments nebulized to average about 1 kb in length have a distribution with the majority of the ma- terial in the range of 7OO-1300 base pairs. In addition, the technique takes less than 15 min to perform, and it is very easy to control the size range of the DNA by altering the gas pressure blowing through the nebuiizer, the viscosity of the liquid and the duration of nebuiization.

One more advantage is that dispos- able nebuiizers, such as the ‘Up-Mist medication nebuiizer manufactured by Hospitak or a similar unit made by iP1 Medical Products inc., Chicago, IL, USA, and used for delivering respiratory drugs, are available from any medical supply store. These cost less than US$2.00 each, and the disposable units can be re- used for simii?r experiments if there is no concern for contaminating the DNA3.

Ian York suggests one modification of the procedure is to place a piece of plas- tic tubing over the end of the output nozzle. The opening can then be further reduced in size by covering it with masking tape and slicing the tape with a razor blade to make a tiny slit. He says

that this prohibits the liquid from dis- persing too rapidly, and it increases the volume of liquid recovered by IO-20% for a total recovery of 80-90% of the ap- plied DNA. The recovery of sample is, after all, an important consideration when making libraries from scarce DNA sam- ples. For example, only about l-3 pg of mitochondriai DNA is all that is needed to establish a clone library because it has a relatively small genome of 5040 kb.

The drawbacks of nebuhzation are that it is a little more technically de- manding than needle aspiration, and if the DNA has been previously mistreated or nicked by enzymes, the DNA might be sheared inconsistently. However, netters say this is not so mu& a problem, and would occur regardless of the shearing method used. One person did point out that care must be taken not t aspirated DNA, especially if from a pathogenic microorga or any malignancy, as epit cells can be transformed di

Ail in ail, netters say that n is quick and easy to learn, consistently obtain good it. They say that to perf

_ _ _ __ ____~ l_l --_- -_ - - -

The term ‘Java’ has become a catch- word in computing as have ‘Internet’ and ‘WWW’. Java is an object oriented- programming language developed by Sun Microsystems and especially designed to meet the portability requirements of gio- bai compunng. With the in-built support of Java applications (called appiets) in popu- lar WWW-browsers such as NetScape, Java has seen an unprecedented career as a programming language. It allows the development of programs that can be run virtually instantaneously at even the remotest sitas of the Web within the regular WW’V-browser, This can be done irrespective qf the computer system in use and without the need of distributing the code (‘program once - run anywhere’; a collection of available Java programs can be found at http://java.wiwi.uni- frankfurt.de.). Java programs are di- rectly transferred to the client upon re- quest (WWW-link) and are interpreted and executed on the client’s machine. It is

therefore much easier to maintain pro- grams, and the user always runs the very latest version. However, the speed of the transfer is, of course, dependent on the WWW-load (as some sceptics are say- ing, W%W stands for World Wide Wait).

The potential of Java not only lies in animated text banners or clocks added as decorative accessories to per- sonal web pages, but also in scientific computing where speed limitations of Java-programs are increasingly aiievi- ated by installations of JiTs (Just in Time Compilers) or dedicated Java chips.

With this communication, I wish to announce WebMoi: a Java-based interac- tive graphical program to display and ana- iyse molecular structures stored in the Protein Data Bank (PDB’). WebMol runs under Java-supporting WWW-browsers without the need of any further software installation. A list of the graphical features and analysis tools that comprise WebMoi can be found in Box 1.

low-cost shearing, all you nee lizer, tygon tubing and maskang tape to cover the breathing hole.

CIB 1 Oefner. P. _I. et al. (1996) Nucleic Act& Res. 24.

3879-3886 2 Okpodu. C M. et al (1994) BmTechnrques 16,

154-159 3 Bodentelch. A. et al. (1994) in Automated DNA

Sequencrng and Analysis (Adams. M. D.. Fields. C. and Venter. J. C., eds). pp. 42-50, Academic Press

4 Alton. E. W. F. W. et al. (1993) Nat. Genet. 5. 135-142

National Cancer Institute. Faederlelc Cancer Research and Development Center. Fwderick, rv?a 21702-1201. USA. Email: pnhQnclfcrf.gov

_-.--__I_- Any statements made by the author are not meant to advocate the use of a partwlar com- mercial product or endorse any company. All opinions are those of the author and do not necess- arily reflect the opmion of the Nailonal Cancer Institute or the National Institutes of Health.

An archive of Methods and reagents articles is available on the Internet and can be obtained by anonymous ftp from ftp.ncifcrf.gov in the direc- tory pub/methuds/flBS. or on the World Wide Web from http://wwwlmmb.nctfcrf.gov/-pnh/ ____-____~_ _I__--_-_

different colormg sctwmes and Iabelbng

side-by-side stereo view with adjustable separation of the images mouse-driven rotation, zoom, translation and drawing slab manipulations focus selection (i.e. setting point of ro-

esired position)

measurements of inter-atomic angles and dihedral angles atrix plot5 [Matrix (or map) of

W-z-residue pairwise distances matrix cells color-coded by their

distance]. Distance maps allow detection of structural similarities between different proteins or protein regions and recog- nition of domains residue-residue identity matrix plots (de- tection of sequence repeats) Ramachandran plot with the preferred regions as observed in globular proteins highlighted in tine plot

B numerical calculation of solvent access- ible surface area

214 Copyright 0 1997. Elsevier Science Ltd. All rights reserved. 096%0004/97/$17.00 PII: SO968-0004(97)01055-4

Bled aF the Europeana

heidelbelg.de/cgi/~Iiewe~pl guides the user to eltber select a regular

installed WebMoE viewer containing the particular structure are generated auto-

saved via copy/ program is menu- cuted within html

pages or in separate windows. ~~~~~~~ was developed under the

nt and tested

0 ~arF~c~~as, the caicdation ng times of CsoF surfaces are comJsnient.

Otiler l~m~t~~g factors of Java a security sestrictisms applied to services, for example, file output op- erations, i.e sav

will be essential to balance security measures with f~~ct~Qna~~ty.

for structure analysis. For instance, the geometric analysis of ondary structural ele

ees 1 Bernstein. 6. J. 6. et al. (1977) J. Mu/. Bid.

112. 535-542 2 Sayle. R. A. end Miner-White. E. J. (1995)

TrencJs Bmhem. So. 20. 374-376

University of Cahfornm. San Francisco, i)epartment of Cellular and Ftiolecuiar Pharmacology, San Francisco, CA 94143-0450, USA. Email: walther@cmpharm.ucsf.edu

As must be the case in any field of sci- ence, there is always a rise and a decline in research activity and general interest in any subject of study or exper~~~el~t~~ systems used in biological science. In a highly i~terestfng recent article, John Precr lamented the decline of Paramecium genetics and attempted to find the rea- son for the decline’. When I was asked to write an essay on ribosome reconsti- tution, which was first achieved success- fully in late 1967, I thought about Preer’s article, remembering the heyday of ribo- some research and the youth, good or bad, I had in those years, that is from the late 11950s to the early 1970s. Of course, ribasomes are essential machinery used by all living cells to make proteins, and their structure and function as well as their biosynthesis is still a subject of current research. I told myself that the dec!ine in the popularity of ribosome re- search is different from the decline in the popularity of Paramecium genetics, and that descriptions of ribosomes will

never disappear from college text books on biology or m~lecufar biology. Still, it might be interesting to reflect on those

eydays of ribosome research. So, even though I have written essays related to this topic before, includmg an extensive historical article on ribosome research*, I have agreed to write a short essay, re- counting how we were doing research. specifically research on ribosome as- sembly, in the days before the develop- ment of gene cloning and engineering and before the current growth of modern eukaryotic molecular biology.

on vimsee The story of the discovery of ribosome

reconstitution must start with the time of mRNA discovery. I came to the United States in late 1957 and worked as a post- doctoral fellow for three years in three different laboratories: first two years in the laboratory of the late Sol Spiegelman at the Unhersity of !!lincis, Urbana, with two interrupting summer periods, when

Cambridge, and the third year, in the lab-

transfer from genes to proteins. As is well known, Francis Crick formulated the central dogma and specificaily proposed that RNAs contained in the ribosomes are the Information carriers between DNA and proteins3. Several years earlier,

ecnick and co-workers ha fied the ribosomes as the site of protein synthesis. Thus, ribosomes were becom- ing the subject of intensive studies by both biochemists, who were interested in the mechanism by which amino acids are polymerized into proteins, and by molecular biologists, such as Jim Watson, who were interested in the mechanism of information transfer. In additicrn, as exemplified by George Palade, who was the first to establish the presence of ribosomes both free and bound to the endoplasmic reticulum by electron ml- croscopy, cell biologists interested in subcellular structures also started to participate in ribosome research.

It should be mentioned that ribosomes were the first ce’riular ribonucleoprotein particles identified, and their initial stud- ies were influenced by the knowledge

Copyright 0 1997, Elsevier Science Ltd. All rights reserved. 0968-UOO4/97/$17.00 PII: S0968_0004(9T)01059-1