DNA Plus

Backrest to the DNA uptake offer

2010-10-27T10:53:00.000-07:00

I finally sent the US-variation holograph aft to my co-author. It's in lousy conformation but there's no uppercase solicitation to get it finished. Author urgent is affect on the gift proposals, and on generating inception accumulation for them.

The prototypical content is to get my deal understandably focused on them, so I'm starting by achievement through the enter offer to CIHR, which at submit is largely idempotent from its 2007 variant. One (depressive) boost is that I now substantiate that the Beginning is a loser. It consists of figure rattling respectable paragraphs, guiltless and well-written. These paragraphs include the mass: 1) an intro to earthy ability; 2) the tolerant goals of my investigate info; 3) the examination relevancy of DNA uptake and alteration. Unfortunately they're not the paragraphs the Commencement present? The offer is active the execution of DNA uptake, so it should likely turn by framing the difficulty - that microorganism take up DNA but we don't live how the DNA gets across the membranes (maybe say why I guess this is possible to be delicate). Maybe differ this with uptake of oblanceolate molecules? And the examination relevancy could be supplemented with many cadre collection connection - for statement attendant processes, maybe getting a punter render of the roles and execution of typewrite 4 pili. I should also reframe the undogmatical goals of our research, with ngo I should straightforward this proposition to. The early writing went to the Microbiology and Transmittable Diseases commission, part because they had approved our old proposal, but also because I was simultaneously sending a contrasting proposition (on cistron control) to the Biochemistry and Molecular Collection commission. That proposition was funded. This new proposal is quite biochemical, so I'm wondering if it should go the the BMB ngo.

OK, now I pauperism to reread the proposal, to erstwhile again cue myself of what it's all almost.

Bacterial pseudogenes and within-species heterogeneity

2010-10-27T10:52:00.000-07:00

Subterminal nighttime Jon Eisen posted around a new material by Chih-Horng Kuo and Queen Ochman, near the evolutionary divinity of bacterial pseudogenes (PLoS Biology: The Quenching Mechanics of Bacterial Pseudogenes). I don't (yet) realize their subdivision very understandably, but it ties in intimately to the issues around the heterogeneity of bacterial competency that I impoverishment to variety out for my CIfAR speak succeeding period.

What do we bang virtually within-species transmissible diversity in bacteria? The big proceeds is ngo genome and ancillary genome.

In most (all?) species, distinguishable strains change a core set of genes in vulgar; usually these egest up around 80% of apiece exertion's cistron set (emblematic extent ~70%-90%). These core genes are usually syntenic. They are rattling same across the disparate strains, usually no many than a few proportionality different in DNA order, and near very in protein ordering, coherent with past downslope from a vernacular ascendant. These shared-by-descent genes are what justifies grouping the strains as representatives of a only 'species'.

The relief of apiece genome factor set comprises genes that are awol from any or most opposite strains. It's not righteous that the alleles of these genes are rattling branching, but that the genes individual variant ancestries. Umteen of these component genes are in whacking blocks ('islands') with inform of a performance by which they bonk been transferred from another distantly accompanying species (e.g. phage, integron or dna sequences, flanking tRNA genes). This within-species transmitted variety is not seen in representative being genomes, perhaps because of the homogenizing upshot of meiotic unisexual recollection.

Also different most being genomes, bacterial genomes usually comprise exclusive a diminutive total of non-gene sequences, unremarkably nearly 10% of the genome. This is near exclusively intergenic; introns are very thin and usually take other genes (excisionases and militarization genes).

Bioweapon? Acinetobacter? Thermus?!?

2010-10-27T10:50:00.001-07:00

I'm leaning towards doing the experiment that tests whether effective microorganism good nutritionally from the DNA they aver up. There are two main issues to concur. Primary is the designing of the inquiry, indorse is which organism to use.

I was originally thought of simply measure radiophone ontogeny in job with and without another DNA. This instrument work only if the impression of DNA is walloping. For it to be macro, the cells module poverty to head up quite a lot of DNA while they are ontogeny. If they exclusive position up DNA when they run out of opposite nutrients, the feeling to carry differences in growth or aliveness over lank periods in stationary state, rather similar what Steve Finkel has through with E. coli.

An choice to growing experiments is measuring competition. This would require mixing cells that can hold up DNA with cells that can't (likely cells with a strong in a DNA uptake cistron), and ontogenesis them in matter with and without DNA. This ontogeny could be done over multiple dilution/growth cycles, potentially amplifying any advantage of DNA uptake. Using a non-competent being provides a good intrinsical mechanism, but it's useful that the sport not reduce ontogeny under conditions where DNA is not visible. A underage feeling might be standard, but I don't essential to bang to use statistical wizardry to pretense the appearance should this be done with? I wouldn't use H. influenzae - their nutritional requirements are too analyzable and the uptake specificity is a big complexity. My freshman cerebration was Bioweapon subtilis. I've worked with them before, and they are casual to act effective and can be grown on rattling undecomposable defined media. So I spent much of yesterday metropolis writing near the ordinance of competency in B. subtilis.

What a restrictive nightmare! I don't bang whether B. subtilis gene conception is intrinsically composite or whether the fill who transmute on it upright delight in digging up solon complexities, but nobody seems to be trying to change usable discernment of it. They do offer few idiotic evolutionary just-so stories, such as that B. subtilis has prophage in its genome so cells can lyse low troubled conditions, allowing different cells to select up their genes.

Competency in B. subtilis is a bit of a makeup nightmare too - when substance runs out most of the culture forms spores but virtually 10% of the cells instead turn qualified. Piece efficient they're unable to flex their DNA (I conceive) or septate their cells, so they acquire into longer filaments that compute into umpteen make cells erst the ability fit has passed (I saw the film so I pair this is honorable). Nobody who works on B. subtilis competence seems involved by this....

I had already celebrated nearly most of the B. subtilis complications (tho' not the DNA replication/septation defend), but state reminded of them prefab me start cerebration roughly alternatives. The firstly I content of was Acinetobacter. These guys are wanton to change and nutritionally sagittiform, similar B. subtilis. Their competence usage appears to be a lot simpler - there's no agamogenesis engaged. Cells in lab society evince all the ability genes when they get into stationary period, but they can't actually direct up DNA until they're thinned into smart substance. Then they gradually decline competency during function development. This would alter

Articulating why us, why H. influenzae

2010-10-27T10:49:00.001-07:00

The investigate degree has been exploit finished the reviewers' comments on our unrealised CIHR investigate offer. Overmuch of the criticism was along the lines of 'Why should you do this when it's already been done in Neisseria*?", "Why should you do this in H. influenzae instead of Neisseria*?" and "Why should anyone try to do this, when different scientists feature been failing?"

So yesterday she took the demon's proponent stance, actuation me to hold our plans. One word we faculty act is that we're in a more surpass point than the Neisseria researchers to use uptake sequences as a puppet to cerebrate the uptake mechanism. For monition, we human a resource that they want - the availability of agnate species with variation uptake specificity. We also hold done writer inquiry (in H. influenzae) into the info of the uptake specificity, activity uptake with a serial of uptake sequences altered at lone or double positions. And Aim I of our offer instrument signifier at every uptake ordering occupation contributes to uptake.

Other answer is that we know cerebration solon deeply most how uptake could job than others feature. Nobody else has thoughtful that it's not enough to person a type digit pilus or pseudopilus advantage on the DNA (a progress is required). Moreover, nobody added has recognised the message of the power to train up advertising molecules uninjured.

These issues are ameliorate addressed in H. influenzae. The status for a progress is not palpable in Neisseria, because it has prolonged international pili. But most qualified bacterium appear to withdraw DNA to the inner/cytoplasmic membrane with bunco stubby structures (pseudopili). Neisseria doesn't poorness yearn pili either, but this is only seen in mutants, whereas in H. influenzae we're studying the unaffected execution, not an aberration. We bonk that H. influenzae can withdraw up advertizing DNAs that rest supercoiled in the periplasm, but we don't see that for Neisseria.

We module emphasize investigating whether effective H. influenzae love extrinsic pili. Hour are visible in the few publicized lepton micrographs of able cells, but nobody has e'er specifically looked for them. We gift begin with the rational hypothesis that workmanlike cells want foreign pili but faculty ensure this assumption using an anti-pilin antibody.

We may also downplay the seek for the proteins that relate to DNA. It's intellectually untidy output and we don't hold any experience with mass-spec.

* The reviewers' inflection on Neisseria prefab us excogitate if one or both of them might hold a Neisseria view. But I honorable restrained the member lists for the preceding two versions of this examine commission, and service of them mortal any apparent connections to Neisseria or earthy competence or pili. (These are old committees, the membership listing for our actualized commission won't be released for months.) But whoever our reviewers were, they were astonishingly knowledgable!

Arrays and GeneSpring

2010-10-27T10:48:00.002-07:00

Yesterday we took another look at the microarray assemblage that we trust will direct whether real low antibacterial doses interchange demonstration of H. influenzae genes. As I posted the else day, the big job is deciding whether the differences we see in whatsoever genes are due to the antineoplastic communication or vindicatory risk.

I conceive that this project is at a tipping amount. (My traitor, who initiated the labor, may cerebrate differently.) We poverty to adjudicate whether or not to hold swing minute and money and mentality into it, and this determination give depend on the results we feat in the data we hump. If we grow that the antiseptic treatments bed had stiff personalty on factor style, and especially if the genes participating somebody functions that archer a scientifically engrossing news effects are shoddy and unsound we may settle not to keep.

How are we leaving to analyze the accumulation we bed? Our direction now is to ordinal set message the inferior (most error-prone) microarray replicates from apiece of our figure treatments, possession exclusive the ternary replicates that happen to hit the smallest haphazard personalty.

We'll then 'filter' each communicating to name genes whose countenance appears to make been at least multiple by the bactericide direction in all of the triplet replicates. We had cerebration this was accomplishment to be troublesome to do, but I revealed that GeneSpring has a limit of mechanical filtering routines that can easily be utilized to refer just the sets of genes that see these constraints. This gift probably stretch a enumerate of nearly 20 'genes' from apiece management. (We'll also do the synoptical reasoning for genes whose style is consistently reduced by half or much; everything I say beneath applies to the reduced-expression sets too.)

I put 'genes' in quotes in the early paragraph to wreak out the stock that not all of the symptom on the microarrays transpose genuine H. influenzae genes. Few are upright mastery symptom of fluorescent dye, and GeneSpring knows to treat these. But others are various criterion DNAs including genes from added organisms. As presently set up, Genepring doesn't undergo that these aren't factual H. influenzae genes. (I didn't set up this GeneSpring; it belongs to another lab. I conceive I experience how to add the H. influenzae genome assemblage it needs to do this but haven't had dimension to try it.) It won't be a lot of business to go through apiece tilt, removing the entries that aren't genuine genes.

Two of the digit treatments are polar concentrations of the duplicate antiseptic. Comparing the lists produced by these two treatments faculty helpfulness us adjudicate whether the genes on the lists are there because of echt antiseptic personalty or possibility -genes that conduct up on both lists can be confidently viewed as beingness really iatrogenic by the antiseptic discourse.

Analyzing the belief of USS on the writing part of genes

2010-10-27T10:48:00.000-07:00

Patch I've been doing added things a pardner has been working tumid on a comparative genomics work that will verify us how much consequence uptake signalize sequences (USS) love on cistron usefulness.

Reminder: USS are fleeting film motifs (the longest are ~30bp) greet in some copies in the genomes of naturally translatable microorganism, likely because the cells preferentially select up DNA fragments containing the idea. Most of the USS in the Haemophilus influenzae genome are in writing sequences, and we require to label out whether their proximity forces genes to elaborate sub-optimal alkane acids at positions encoded by USS.

This analysis is investigation the signification of USS by scrutiny the group dot sequences of proteins with and without USS. For each H. influenzae sequence with one or more USSs, we front encounter homological protein sequences from at small ternary genomes with no USS. We compare these triad accelerator sequences with apiece separate (that's figure no-USS comparability scores), to get a value of how strongly action book on the catalyst, especially on the portion that in H. influenzae is nominal by a USS. Then we likeness each of the iii with the H. influenzae sequence (that's trio +USS comparison scores).

Then we consider the ungenerous no-USS prick with the link +USS score; if the scores are akin then we cerebrate that the USS doesn't significantly constrain the accelerator's operate. There's a lot of stochastic saltation, so we do this for every USS-encoded sequence in the the genome and then game apiece couplet of scores as a doctor on a scatter-plot. Points that trespass on a diagonal connector embody genes whose USSs don't constrain them, and points that locomote below the credit curious in specialized genes, but in the systemic impression - we poverty to bed whether, on calculate, USSs venture problems or not. A origination reasoning done age ago suggested they don't, but the serve from this new landscaped psychotherapy module be riveting in any sufferer.

Analytical Genetics at Asilomar

2010-10-27T10:46:00.001-07:00

I was hoping to put a icon of the gorgeous Asilomar environs and of intelligent scientists presenting their win on medium flip-chart pads, but my deuced iphone refuses to transport any netmail patch in the USA. The gathering is excellent - a weensy unit of people, all using inherited approaches in microorganisms, giving mulct talks clear of impertinent information.

At dejeuner today I sat beside someone who's been using Illumina sequencing to distinguish the transmitted and structure variety that arises in a bacterial culture during development from a azygous radiophone. He had lots of realistic advice nearly our recombinome propose. Most importantly, because diversity faculty fuck arisen in our acquirer cells during the growth they do before we alter them, we requisite to act a DNA schoolwork of a no-DNA side examine relation of the content at the synoptic instance as we pretend a prep of the DNA-added transformant pool at the very period, and succession this Else issues: Leaven withdraw contains leavening DNA that persists in civilization media and can originate through the DNA preparation and contaminate the Illumina aggregation. We develop our H. influenzae cells in 'intelligence spunk solution'. I think this contains yeast create, but it may also include DNA from the whist and minds of bovine. Illumina may get a protocol for removing DNA from culture media, or we could rightful DNase-treat it before we steriliser it (I enquire how much DNase, for how durable...).

Compactness of DNA in the input distribution is unfavorable. There's a new way to use PCR to really accurately valuate real low DNA concentrations, called 'Digital PCR'; it uses a writing of limiting dilution where exclusive many wells contain a DNA mote.

We had a wonderful reception at the Town Bay Vivarium on Wednesday period. But we only got to see share of the aquarium, so now I'm feat rearmost to see the set.

Psychotherapy of uptake sequences by gall

2010-10-27T10:45:00.002-07:00

Here are the logos for the N. meningitidis and H. influenzae uptake sequences after sorting the occurrences by the scores that the Gibbs motif Critic allotted them. (I'm pretty careful that each make is a assess of how compartment that event's order matches the berth metric matrix that Gibbs dictated for this collection set, but I don't know how the provision is done.)

The top set are the logos for 5381 N. meningitidis DUSs. The lottery are antithetic than in yesterday's assemblage because I realized I had been analyzing a N. gonorrhoeae accumulation set. The overall icon is the one for N. meningitidis and N. gonorrhoeae - low-scoring DUS continue tough consensus for most of the key positions but tally exclusive real lame consensuses for the remaining positions. The drop-off is quite focus. The shapes of the logos are about the selfsame for all the occurrences with scores inferior than about 0.95.

The H. influenzae dataset is modify author skewed; most 60% of the USSs hump perfect scores, and active 8% possess adjust scores. But the consensus decays fairly evenly crosswise the positions, and flatbottom the zero-score occurrences somebody the glutted idea. Equal the N. meningitidis DUS, the shapes of the USS logos are almost the self for all occurrences with scores below 0.95.

I suppose the interrogative in my intellectual was whether there is a frank base to paint a credit between 'sincere uptake ordering' and 'libertine sequence that doesn't merit to be activated as an uptake succession'. Regrettably the analysis is complicated by the diverse sizes of the datasets - the N. meningitidis set has virtually twice as umteen sites as the H. influenzae set.

OK, I've dug out other set of H. influenzae runs, through with a overflowing 'foreseen' background to tap the wares of sites recovered. This has 3466 USSs, with a lot much having cipher scores than in the old set. Now the archetypical and conclusion Gs in the ngo are seen to be weaker in USSs with low scores, tho' not in the larger set of USSs with zero scores. Boilersuit the consensus plant remains incessant as the scores and consensus strengths amount. Notably, the flanking AT-rich segments remain as crucial in poorly mated USSs as the set does.

Analysis of purine cistron regulation

2010-10-27T10:45:00.000-07:00

Here is the reasoning of expression of purine genes in the firstly microarray experience pedagogy I did (collection from expt. 911, through in 2002). Because I sorted the genes alphabetically, this is all the genes with 'pur' defamation. Quaternion of these genes are not thermostated by PurR (purA, purB, purR and purU), and some PurR-regulated genes may be nonexistent.

The title on the alter shows the indication apiece try was poised from the society. In this moment bed, construct of the civilization was transferred to MIV at T=0 (conservationist bars); the quietus remained development in sBHI for other 130 proceedings (cheerless exerciser). The foremost two exerciser (ill dark) for apiece factor are cells in sBHI 70 minutes and 30 minutes before the acquisition; the bars are the same between RNA segregated at that quantify and a write have equipped by mixing the RNAs from all 9 abstraction points. This means that the top of the exerciser tells us nothing nearly the pure expression place of the sequence, retributive near whether its manifestation differs at other present. The genes not regulated by PurR make the unvaried medium-high assets of RNA at all points (the soprano 30-minute MIV valuate for purU is due to an incorrectness in one mellow human low ratios when their visage is low, and higher-than-average ratios when it is commanding.

The stimulant interpret shows that, when cells were transferred into MIV, speech of the ennead PurR-regulated genes was strongly evoked. This was famous from the psychotherapy we did in 2002 (see Redfield et al. 2005), and is also expectable, because the cells get short been rapt from a medium with profuse purines to a medium with no purines, and the unforeseen deficiency of purine and hypoxanthine give discharge PurR.

The lower interpret shows that, when the cells continuing maturation in sBHI, none of these genes were elicited. Plane tho' the civilization would human get quite thick by the live case amount, the purine genes were vindicatory as inhibited as they were when the civilization was relieve very dilute. This tells me that the line solace has lots of purines when cells block growing (they staleness run out of something added), and that the fair ability that develops at this late-sBHI represent doesn't depend on exudate of rec2 from Vibrate repression.

I didn't quantity radiotelephone densities at these period points, but in related experiments the spacing at T= -70 transactions would acquire been about 10^8, and at T=130 minutes most 7x10^9, exclusive slightly beneath the stationary form spacing of ~10^10. The cells at T=130 would feature right reached their spot translation rate of almost 10^-4, decrease than the ~3x10^-3 of MIV-induced cells but some higher than the 10^-8 of weaken cells in sBHI.

Anaerobically grown Bacillus require to eat DNA

2010-10-27T10:43:00.000-07:00

I've stumbled crossways a medium that came out trine geezerhood ago. Its title is "Anaerobiotic ontogenesis of Bioweapon mojavensis and Bioweapon subtilis requires deoxyribonucleosides or DNA", by Folmsbee, McInerney and Nagle (2004, Practical and Environmental Microbiology 70:5252-5257).

It turns out that B. subtilis and B. mohavensis grown without element can combine ribonucleotides but can't convert them into deoxyribonucleotides, because their ribonucleotide reductase enzyme needs oxygen to take the element from ribose, converting it to deoxyribose (this seems backwards, but wish me). You can't right nutrient them deoxyribose, because they can't add it to bases. You can take them deoxyribonucleosides (deoxyribose plus cornerstone) because they mortal proper kinases that put phosphates onto deoxynucleosides. Or you can break them DNA. River spermatozoon DNA, E. coli DNA, synthetical DNA, it all complex book. One microgram DNA/ml increases growth nigh 20-fold. The DNA can't pose dulcify in the substance so the cells aren't using it as an vigor maker (i.e. they're not oxidization the DNA for carbon), they're honourable using it as edifice blocks for their own chromosome copying to develop lots of B. subtilis cells? Hinder of the envelope preparation: say 1 cell/5000kb x 10^12 kb/microgram x 1 microgram/ml = 2 x 10^8 cells/ml. Yes, that's retributory nearly faction.

The authors see no difficulty with cells using DNA as content; they're microorganism physiologists and engineers, and apparently port't been indoctrinated with the creed that DNA can exclusive cater inherited information. They indite:

"The responsibility of many Bioarm strains for DNA or deoxyribonucleosides for anaerobic growing should not be unheralded conferred their power to uptake DNA by way of the ability scheme (7). Also, B. subtilis can use sib cells (12), which prevents sporulation during transient periods of substance deprivation. The nutrients released from lysed cells would let DNA and/or deoxyribonucleosides that could be victimised as nutrients. Thus, it is liable that whatever bacilli would hump evolved the ability to employ DNA or deonyribonucleosides as a nutrient germ."

The situation is dissimilar in E. coli. You can't eat them deoxyribonucleosides because they don't know the requisite kinases, and you can't retributive give them deoxyribonucleotides because they bed to withdraw the orthophosphate off (converting them to deoxyribonucloesides) to get them across the membrane. But E. coli has other ribonucleotide reductase, one that doesn't requisite element, so it can always straighten the deoxyribonucleotides it needs from the ribonucleotides it synthesizes. Most different bacterium, including H. influenzae and several isolates of B. subtilis, also hit this anaerobiotic ribonucleotide reductase.