Applied Biosystems

About: Applied Biosystems is a based out in . It is known for research contribution in the topics: Mass spectrometry & Capillary electrophoresis. The organization has 1521 authors who have published 1579 publications receiving 285423 citations.

ESX-1 secreted virulence factors are recognized by multiple cytosolic AAA ATPases in pathogenic mycobacteria.

Abstract: The ESX-1 secretion system of Mycobacterium tuberculosis delivers bacterial virulence factors to host cells during infection. The most abundant factor, the ESAT-6/CFP-10 dimer, is targeted for secretion via a C-terminal signal sequence on CFP-10 that is recognized by the cytosolic ATPase, Rv3871. However, the selection determinants for other ESX-1 substrates appear to be more complex. Some substrates, such as ESAT-6, are secreted despite lacking signal sequences. Furthermore, all substrates require targeting of the other ESX-1 secreted proteins, a distinguishing feature of this system. How ESX-1 substrates are selected and the basis for co-dependent secretion is unknown. Here we show that the EspC substrate interacts with Rv3868, a cytosolic AAA ATPase, through its C-terminus. Swapping the C-termini of EspC and CFP-10 revealed that these signals are functionally distinct, suggesting that the proteins are targeted via interactions with different ATPases. Surprisingly, biochemical purification experiments demonstrate that these substrates and ATPases form multi-protein complexes inside the cell and identified a new secreted substrate. By interfering with this protein interaction network, we have partially uncoupled co-dependent substrate secretion. Our results suggest that proper functioning of the ESX-1 pathway requires the interaction of multiple ESX-1 substrates and components prior to their secretion. Ultimately, understanding the details of ESX-1 targeting may allow for engineering of better vaccines to prevent tuberculosis.

Overexpressing Cu/Zn superoxide dismutase enhances survival of transplanted neurons in a rat model of Parkinson's disease

Abstract: A high survival rate of grafted dopamine neurons is crucial for reversing neurological deficits following brain tissue transplantation in Parkinson's disease. For unknown reasons the survival rate of transplanted dopamine neurons is only around 10% in experimental animals. The hypothesis that oxidative stress causes the loss of transplanted neurons was tested by grafting neurons from transgenic mice that overexpress Cu/Zn superoxide dismutase. Compared with the survival of those taken from non-transgenic littermates, the survival was 4 times higher for the transgenic dopamine neurons with a concomitant more extensive functional recovery. The results provide direct support for the free radical hypothesis of dopaminergic neuron death in brain tissue grafting.

An efficient method for the isolation and purification of oligoribonucleotides

Abstract: Problems associated with the use of tetrabutylammonium fluoride like incomplete desilylation and removal of the tetrabutylammonium salts during large scale syntheses of oligoribonucleotides (RNA) have been eliminated by the use of triethylamine trihydrofluoride and precipitation of the RNA with 1-butanol. An efficient anion-exchange HPLC method has been developed for the purification of chemically synthesized RNA and the resulting product precipitated directly by the addition of 1-propanol. A new activator, 5-ethylthio-1H-tetrazole significantly enhances the synthesis quality and yield of oligoribonucleotides. RNA synthesized using these improvements has been shown to be biologically active by a comparative ribozyme-substrate assay.

Expression and interdependencies of pluripotency factors LIN28, OCT3/4, NANOG and SOX2 in human testicular germ cells and tumours of the testis.

Abstract: OCT3/4, NANOG, SOX2 and, most recently, LIN28 have been identified as key regulators of pluripotency in mammalian embryonic and induced stem cells, and are proven to be crucial for generation of the mouse germ-cell lineage. These factors are a hallmark of certain histological types of germ-cell tumours (GCTs). Here, we report novel information on the temporal and spatial expression pattern of LIN28 during normal human male germ-cell development as well as various types of GCTs. To investigate LIN28 expression, immunohistochemical analyses and quantitative proximity ligation assay-based TaqMan protein assays were applied on snap-frozen and formalin-fixed, paraffin-embedded samples as well as representative cell lines. LIN28 was found in primordial germ cells, gonocytes and pre-spermatogonia, in contrast to OCT3/4 and NANOG, which were found only in the first two stages. LIN28 was also found in all precursor lesions (carcinoma in situ and gonadoblastoma) of type II GCTs, as well as the invasive components seminoma and the non-seminomatous elements embryonal carcinoma and yolk sac tumour. Choriocarcinoma showed a heterogeneous pattern, while teratomas and spermatocytic seminomas (type III GCTs) were negative. This expression pattern suggests that LIN28 is associated with malignant behaviour of type II GCTs. Cell line experiments involving siRNA knockdown of LIN28, OCT3/4 and SOX2 showed that LIN28 plays a role in the maintenance of the undifferentiated state of both seminoma and embryonal carcinoma, closely linked to, and likely upstream of OCT3/4 and NANOG. In conclusion, LIN28 regulates the differentiation status of seminoma and embryonal carcinoma and is likely to play a related role in normal human germ-cell development.