The complex evolutionary dynamics of vertically transmitted symbi

The complex evolutionary dynamics of vertically transmitted symbiotic bacteria

have led to distinctive symbiont genome characteristics that have profound effects on the phenotype of the host insect. Symbiotic bacteria are key players in insect-plant interactions influencing many aspects of insect ecology and playing a key role in shaping the diversification of many insect groups. In this review, we discuss the role of endosymbionts in manipulating insect herbivore trophic interactions focussing on their impact on plant utilisation patterns and parasitoid biology.”
“Hepatitis E virus (HEY) infections are responsible for chronic hepatitis in immunocompromised patients, and this can evolve to cirrhosis. Like all RNA viruses, HEV exists as a mixture of heterogeneous viruses defining quasispecies. The relationship Dinaciclib cell line between the genetic heterogeneity described as a quasispecies, cytokine secretion, and the outcome of acute hepatitis in immunocompromised patients remains to be elucidated. We cloned and sequenced the region encoding SNS-032 supplier the M and P capsid domains of HEV from eight solid-organ transplant (SOT) patients with acute HEY infection who subsequently cleared the virus and from eight SOT patients whose infection became chronic. We

analyzed the cytokines and chemokines in the sera of these SOT patients by multianalyte profiling. The nucleotide sequence entropy and genetic distances were greater in patients whose infections became chronic. A lower K-a/K-s ratio was associated with the persistence of HEY. The patients who developed chronic infection had

lower serum concentrations of interleukin-1 (IL-1) receptor antagonist and soluble IL-2 receptor. Increased concentrations of the chemokines implicated in leukocyte recruitment to the liver were associated with persistent infection. Those patients with chronic HEY infection and progressing liver fibrosis had less quasispecies diversification during the first year than patients without liver fibrosis progression. Great quasispecies heterogeneity, a weak inflammatory response, and high serum concentrations of the chemokines involved in leukocyte recruitment to the liver in the acute phase were associated with persistent HEY infection. Slow quasispecies diversification during the first year was associated with rapidly developing liver fibrosis.”
“The life of plants growing in cold extreme environments has been well investigated in terms of morphological, anatomical, and ecophysiological adaptations. In contrast, long-term cellular or metabolic studies have been performed by only a few groups. Moreover, a number of single reports exist, which often represent just a glimpse of plant behavior. The review draws together the literature which has focused on tissue and cellular adaptations mainly to low temperatures and high light.

Thus, attenuation of FMD by ADMA suggests that this endogenous in

Thus, attenuation of FMD by ADMA suggests that this endogenous inhibitor of

NO synthase may, in part, mediate the vascular effects of FGF-23 in patients with CKD. Kidney International (2010) 78, 679-685; doi:10.1038/ki.2010.194; published online 7 July 2010″
“To elucidate the pathophysiologic changes in the kidney due to aging, we used physiological, morphometric, and imaging techniques to quantify GFR and its determinants in a group of 24 older (>= 55 years) compared to 33 younger (<= 45 years) living donors. Mathematical modeling was used to estimate the glomerular filtration coefficients for the whole kidney (K(f)) and for single nephrons (SNK(f)), as well Elacridar price as the number of filtering glomeruli (N(FG)). Compared to younger donors, older donors had a modest (15%) but significant depression of pre-donation GFR. Mean whole-kidney K(f), renocortical volume, Fedratinib and derived NFG were also significantly decreased in older donors. In contrast, glomerular structure and SNK(f) were not different in older and younger donors. Derived N(FG)

in the bottom quartile of older donors was less than 27% of median-derived N(FG) in the two kidneys of younger donors. Nevertheless, the remaining kidney of older donors exhibited adaptive hyperfiltration and renocortical hypertrophy post-donation, comparable to that of younger donors. Thus, our study found the decline of GFR in older donors is due to a reduction in K(f) attributable to glomerulopenia. We recommend careful monitoring for and control of post-donation comorbidities that could exacerbate glomerular loss. Kidney International (2010) 78, 686-692; doi:10.1038/ki.2010.128; published online 12 May 2010″
“BACKGROUND: Based on success with a prototype 1.5T intraoperative magnetic resonance imaging (iMRI) system and the MK-8931 desire for increased signal-to-noise ratio,

along with its relationship to image quality and advanced applications, a 3.0T system that uses the same novel moveable magnet configuration was developed.

OBJECTIVE: To assess clinical applicability by prospectively applying the higher-field system to a neurosurgical cohort.

METHODS: Upgrading to 3.0T required substantial modification of an existing iMRI-equipped operating room. The 1.5T magnet was replaced with a ceiling-mounted, moveable 3.0T magnet with a 70-cm working aperture. Local radiofrequency shielding was replaced with whole-room shielding. A new hydraulic operating table, high-performance gradients, and advanced image processing software were also installed. The new system was used as an adjunct to standard neurosurgical practice.

RESULTS: The iMRI system upgrade required 6 months. Since completion, the 3.0T iMRI system has successfully guided neurosurgery in 120 patients without system failure in a patient-focused environment. Intraoperative image quality was superior to that obtained at 1.

Individuals with the

condition first experience severe pa

Individuals with the

condition first experience severe pain across the shoulder and upper arm. Within a few hours or days, weakness, wasting (atrophy), and paralysis may affect the muscles of the shoulder. Although individuals with the condition may experience paralysis of the affected areas for months or, in some cases, years, recovery is usually eventually complete.”
“OBJECTIVE: Nerves of the pelvic plexus and lower abdominal wall can lead to chronic neuralgias owing to a variety of causes, including iatrogenic injury, trauma, tumors, and primary nerve entrapment. Differentiating among the various neural etiologies can be a challenging task. Here, we present a large series of patients who underwent surgical GSK621 treatment of these nerves, with an emphasis on diagnostic and therapeutic considerations.

METHODS: Between 1970 and 2006, the senior authors (DGK and DHK)

surgically treated 264 cases of neuralgia of the pelvic plexus and nerves. A retrospective analysis of the patients’ history, physical, diagnostic examinations, and follow-up was performed.

RESULTS: Twenty-five cases of solely ilioinguinal neuralgia and 24 cases of combined ilioinguinal Blasticidin S purchase neuralgias were treated. Of these, iatrogenic injury was the most common etiology. One hundred forty-five patients underwent surgical exploration for either femoral nerve injury (119 EPZ015666 manufacturer patients) or lateral femoral cutaneous compression (26 patients). Seventy-five percent of patients had femoral nerve injuries attributable to trauma (iatrogenic versus penetrating injuries), and the remaining 25% of patients had cystic masses or tumors. Fifty-two masses of the pelvic plexus were

treated, including neurofibromas (68%), schwannomas (18%), malignant nerve sheath tumors (5%), and non-neural sheath tumors (9%).

CONCLUSION: Effective surgical management of these complex neuralgias depends on a solid understanding of the surgical anatomy and proper diagnosis. Electromyography and local anesthetic blocks not only can provide insight into the diagnosis but also have predictive value in assessing which patients may benefit from neurectomy or neurolysis.”
“OBJECTIVE: The purpose of this review is to summarize the basic science literature related to chronic nerve injuries, and to then use this as the background to provide emerging insights into the promising role of cellular therapy for nerve injury repair.

METHODS: The literature pertinent to the experimental and clinical aspects of chronic nerve injury was reviewed, as was emerging literature and our own recent experience in using cellular therapy to repair injured nerves.

RESULTS: Peripheral nerves have the potential to regenerate axons and reinnervate end organs. Yet, outcome after peripheral nerve injury, even after nerve repair, remains relatively poor.

To determine a positive result with either dose, the early-start

To determine a positive result with either dose, the early-start treatment group had to meet each of three hierarchical end points of the primary analysis based on the Unified Parkinson’s Disease Rating Scale (UPDRS, a 176-point scale, with higher numbers indicating more severe disease): superiority to placebo in the rate of change in the UPDRS score between weeks 12 and 36, superiority to delayed-start treatment in the change in the score between baseline and week 72, and noninferiority to delayed-start treatment in the rate of change in the score between weeks 48 and 72.


Early-start treatment with rasagiline

at a dose of 1 mg per day met all end points in the primary analysis: a smaller mean (+/- SE) increase ( rate of worsening) in the UPDRS score between weeks selleck screening library 12 and 36 (0.09 +/- 0.02 points per learn more week in the early-start group vs. 0.14 +/- 0.01 points per week in the placebo group, P=0.01), less worsening in the score between baseline

and week 72 (2.82 +/- 0.53 points in the early-start group vs. 4.52 +/- 0.56 points in the delayed-start group, P=0.02), and noninferiority between the two groups with respect to the rate of change in the UPDRS score between weeks 48 and 72 (0.085 +/- 0.02 points per week in the early-start group vs. 0.085 +/- 0.02 points per week in the delayed-start group, P<0.001). All three end points were not met with rasagiline at a dose of 2 mg per day, since the change in the UPDRS score between baseline and week 72 was not significantly different in the two groups (3.47 +/- 0.50 points in the early-start group and 3.11 +/- 0.50 points in the delayed-

start group, P=0.60).


Early VE-822 molecular weight treatment with rasagiline at a dose of 1 mg per day provided benefits that were consistent with a possible disease-modifying effect, but early treatment with rasagiline at a dose of 2 mg per day did not. Because the two doses were associated with different outcomes, the study results must be interpreted with caution. (ClinicalTrials. gov number, NCT00256204.)”
“Rapid depletion of memory CD4(+) T cells and delayed induction of neutralizing antibody (NAb) responses are characteristics of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections. Although it was speculated that postinfection NAb induction could have only a limited suppressive effect on primary HIV replication, a recent study has shown that a single passive NAb immunization of rhesus macaques 1 week after SIV challenge can result in reduction of viral loads at the set point, indicating a possible contribution of postinfection NAb responses to virus control. However, the mechanism accounting for this NAb-triggered SIV control has remained unclear.

We argue that recently the term cognition has been both overused

We argue that recently the term cognition has been both overused and misused. This has led to problems in developing a usable shared definition for the term and to promotion of possible misdirections in research within behavioral neuroscience. In addition, we argue that cognitive-guided research influenced primarily by top-down (cortical toward subcortical) perspectives without concurrent non-cognitive modes of bottom-up developmental thinking, could hinder progress in the search for new treatments Verteporfin in vitro and medications for psychiatric illnesses and neurobehavioral

disorders. Overall, linkages of animal research insights to human psychology may be better served by bottom-up (subcortical to cortical) affective and motivational ‘state-control’ perspectives, simply because the lower networks of the brain are foundational for the construction of higher ‘information-processing’ aspects of mind. Moving forward, rapidly expanding new techniques and creative methods in neuroscience along with more accurate brain concepts, may help guide the development of new therapeutics and hopefully more accurate ways to describe and explain brain-behavior relationships. (C) 2011 Elsevier Ltd. All rights reserved.”

the incidence and prevalence of most common vaccine preventable childhood infectious diseases are constantly low, as is the case in many industrialized countries, the incidence of vaccine-associated side effects might become a key determinant Bleomycin in vaccine demand. We study an SIR transmission model with dynamic vaccine demand

based on an imitation mechanism where the perceived risk of vaccination is modelled as a function of the incidence of vaccine side effects. The model shows some important differences compared to previous game dynamic models of vaccination, HDAC inhibitor and allows noteworthy inferences as regards both the past and future lifetime of vaccination programmes. In particular it is suggested that a huge disproportion between the perceived risk of disease and vaccination is necessary in order to achieve high coverages. This disproportion is further increased in highly industrialised countries. Such considerations represent serious challenges for future vaccination programmes. (C) 2010 Elsevier Ltd. All rights reserved.”
“The philosophical implications of Jaak Panksepp’s affective neuroscience comprise a significant form of skepticism regarding our capacities as agents. This is clear in two ways. (1) Panksepp’s methods of inquiry support a corollary to Dobzhansky’s famous maxim concerning evolution: nothing in mammalian psychology makes sense except in light of ancient affective capacities shared by all mammals. The application of this maxim, I argue, raises informed doubts concerning our knowledge of our own capacities.

1, 95% CI 4 7-26 4) The increased events were observed both from

1, 95% CI 4.7-26.4). The increased events were observed both from discharge to 30 days and from 30 days to 6 months.

Conclusion: Aspirin resistance occurs in similar to 10% of patients presenting with suspected acute coronary syndrome and is associated with adverse cardiac events.”
“PB1-F2 is a small,

87- to 90-amino-acid-long protein encoded by the +1 alternate open reading frame of the PB1 gene of most influenza A virus strains. It has been shown to contribute to viral pathogenicity in a host- and strain-dependent manner, and we have previously discovered that a serine at position 66 (66S) in the PB1-F2 protein increases virulence of the 1918 and H5N1 pandemic viruses. Recently, we have shown that PB1-F2 inhibits PD173074 mouse the induction of type I interferon (IFN) at the level of the MAVS adaptor protein. However, the molecular

mechanism for the IFN antagonist function AG-014699 research buy of PB1-F2 has remained unclear. In the present study, we demonstrated that the C-terminal portion of the PB1-F2 protein binds to MAVS in a region that contains the transmembrane domain. Strikingly, PB1-F2 66S was observed to bind to MAVS more efficiently than PB1-F2 66N. We also tested the effect of PB1-F2 on the IFN antagonist functions of the polymerase proteins PB1, PB2, and PA and observed enhanced IFN inhibition by the PB1 and PB2 proteins in combination with PB1-F2 but not by the PA protein. Using a flow cytometry-based assay, we demonstrate that the PB1-F2 protein

inhibits MAVS-mediated IFN synthesis by decreasing the mitochondrial membrane potential (MMP). Interestingly, PB1-F2 66S affected the MMP more efficiently than wild-type PB1-F2. In summary, the results of our study identify the molecular mechanism by which the influenza virus PB1-F2 N66S protein increases virulence.”
“Fabry disease is a rare lysosomal storage disorder leading to cellular accumulation of globotriaosylceramide, especially in blood vessels. It is associated with severe early onset cerebrovascular disease and kidney and heart failure. The purpose of this study was to reveal possible disturbances in white matter integrity in Fabry disease patients using voxelwise diffusion-tensor imaging (DTI) analysis.

Twelve Fabry disease Bcl-w patients, along with 13 healthy controls, underwent DTI and structural MRI. Voxel-based analysis of the DTI data was performed to assess possible differences in DTI parameters between Fabry disease patients and healthy controls. A selective region of interest analysis was performed for healthy volunteers and Fabry disease patients having a mild burden of T2-hyperintense lesions. We also measured normalised brain tissue volumes and performed a voxel-based volume analysis for grey matter.

Voxel-based analysis of DTI data showed areas of significantly reduced fractional anisotropy and increased mean diffusivity in patients with Fabry disease.

(C) 2007 Elsevier B V All rights reserved “
“Linkage studie

(C) 2007 Elsevier B.V. All rights reserved.”
“Linkage studies have suggested a susceptibility locus for schizophrenia (SZ) exists on chromosome 8p21-22. The vesicular monoamine transporter 1 gene (VMAT1), also known as SLC18A1, maps to this SZ susceptibility locus. Vesicular monoamine transporters are involved in the presynaptic vesicular selleck products packaging of monoamine neurotransmitters, which have been postulated to play a role in the etiology of SZ. Variations in the VMAT1 gene might affect transporter function and/or expression, and might be involved in the etiology of SZ. Genotypes of

62 patients with SZ and 188 control subjects were obtained for 4 missense single nucleotide polymorphisms (Thr4Pro, Thr98Ser, Thr136Ile, Val392Leu) and 2 noncoding single nucleotide polymorphisms (rs988713, rs2279709). All cases and controls were of European descent. The frequency of

the minor allele of the Thr4Pro polymorphism was significantly increased in SZ patients when compared to controls (p = 0.0140; d.f. = 1; OR = 1.69; 95% CI = 1.11-2.57). Assuming a recessive mode of inheritance, the frequency of homozygote 4Pro carriers was significantly increased in the SZ patients when compared to controls (24 vs. 8%, respectively; p = 0.0006; d.f. = 1; OR = 3.74; 95% CI = 1.703-8.21). Haplotype analysis showed nominal significance for an individual risk Selleckchem Pitavastatin haplotype (p = 0.013); however, after permutation correction, the global p value did not attain a statistically significant level (p = 0.07). Results suggest that variations in the VMAT1 gene may confer susceptibility to SZ in patients of European descent. Further studies are necessary to confirm this effect, and to elucidate the role of VMAT1 in central nervous system physiology and possible involvement in the genetic origins of SZ. Copyright

(c) 2008 S. Karger AG, Basel.”
“This report describes LY294002 the development of a one-step reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) assay for the detection of swine vesicular disease virus (SVDV). The assay detects the virus rapidly, within 30-60 min and the result is visualised either by gel-electrophoresis or by the naked eye through the addition of SybrGreen. A collection of 28 SVDV isolates were tested positive, while heterologous viruses such as foot-and-mouth disease virus and vesicular stomatitis virus remained negative. The performance of the RT-LAMP was compared directly with real-time PCR using RNA from clinical samples including nasal swabs, serum and faeces. For nasal swabs and serum the sensitivity of the RT-LAMP was shown to be at least equivalent to real-time PCR. Interestingly, for faecal samples the RT-LAMP assay was shown to be even more sensitive than real-time PCR, possibly because it is less sensitive to inhibitory substances.

Key features of the paradigm that we propose here include differe

Key features of the paradigm that we propose here include differential intrinsic network vulnerability to propagating protein abnormalities, in part reflecting developmental structural and functional factors; differential

vulnerability of neural connection types (e.g., clustered versus distributed connections) to particular pathogenic proteins; and differential impact of molecular effects (e.g., toxic-gain-of-function versus loss-of-function) on gradients of network damage. The paradigm has implications for understanding and predicting neurodegenerative disease biology.”
“Hemolysin is a significant toxin secreted by Aeromonas hydrophila, which contributes pathogenicity of fish to humans. The complete ORF of hemolysin gene (1886 bp) was amplified using PCR. It was cloned in TA and sub-cloned in pET28a vector then transformed into Escherichia coli BL21 (DE3) codon plus RP cells expressed by the induction with 1.0 mM of LEE011 solubility dmso IPTG. The expected

size of expressed protein was 68.0 kDa estimated by migration in 12% SDS-PAGE. Anti-His monoclonal antibodies were used to substantiate the recombinant protein by Western blotting. The percent similarity between hemolysin of A. hydrophila with other hemolytic toxins revealed that the hemolysin/aerolysin/cytotoxin sequence varied from 99.35 to 50.40%. Homology modeling was used to construct 3-D structure of hemolysin of A. hydrophila with the known crystal 3-D structure (PDB: 1XEZ). This protein can be used for immunoassays and it is suitable for vaccine candidate against A. hydrophila infection. (C) 2008 Elsevier Inc. All rights reserved.”
“Early-stage romantic love is associated with activation in reward and motivation systems of the brain. Can these localized activations, or others, predict long-term relationship Lapatinib stability? We contacted participants

from a previous fMRI study of early-stage love by Xu et al. [34] after 40 months from initial assessments. We compared brain activation during the initial assessment at early-stage love for those who were still together at 40 months and those who were apart, and surveyed those still together about their relationship happiness and commitment at 40 months. Six participants who were still with their partners at 40 months (compared to six who had broken up) showed less activation during early-stage love in the medial orbitofrontal cortex, right subcallosal cingulate and right accumbens, regions implicated in long-term love and relationship satisfaction [1,2]. These regions of deactivation at the early stage of love were also negatively correlated with relationship happiness scores collected at 40 months. Other areas involved were the caudate tail, and temporal and parietal lobes. These data are preliminary evidence that neural responses in the early stages of romantic love can predict relationship stability and quality up to 40 months later in the relationship.

In 1940, Oscar V Batson reported the true functionality of the V

In 1940, Oscar V. Batson reported the true functionality of the VVP by proving the continuity of the prostatic venous plexus with the VVP and proposed this route as the most Selleck Anlotinib plausible explanation for the distribution of prostate metastatic disease. With his seminal work, Batson reclassified the human venous system to consist of the caval, pulmonary, portal, and vertebral divisions. Further advances in imaging technology confirmed Batson’s results. Today,

the VVP is considered part of the cerebrospinal venous system, which is regarded as a unique, large-capacitance, valveless plexiform venous network in which flow is bidirectional that plays an important role in the regulation of intracranial pressure with changes in posture and in venous outflow from the brain, whereas in disease states, it provides

a potential route for the spread of tumor, infection, or emboli.”
“BACKGROUND: A significant number of patients with major depressive disorder are unresponsive to conventional therapies. For these patients, neuromodulation approaches are being investigated.

OBJECTIVE: To determine whether epidural cortical stimulation at the left dorsolateral prefrontal cortex is safe and efficacious for major depressive disorder through a safety and feasibility study.

METHODS: Twelve patients were recruited in this randomized, single-blind, sham-controlled study with a 104-week follow-up period. The main outcome measures were Hamilton Depression Rating Scale-28 (HDRS), Montgomery-Asberg Depression Rating Scale (MADRS), Global Assessment

of Function (GAF), and Quality of Life Enjoyment and Satisfaction (QLES) questionnaire. An electrode was implanted over Brodmann area 9/46 in the left hemisphere. The electrode provided long-term stimulation to this target via its connections to an implanted neurostimulator Diflunisal in the chest. RESULTS: During the sham-controlled phase, there was no statistical difference between sham and active stimulation, although a trend toward efficacy was seen with the active stimulation group. In the open-label phase, we observed a significant improvement in outcome scores for the HDRS, MADRS, and GAF but not the QLES (HDRS: df = 7, F = 7.72, P < .001; MADRS: df = 7, F = 8.2, P < .001; GAF: df = 5, F = 16.87, P < .001; QLES: df = 5, F = 1.32, P > .2; repeated measures ANOVA). With regard to the HDRS, 6 patients had >= 40% improvement, 5 patients had >= 50% improvement, and 4 subjects achieved remission (HDRS < 10) at some point during the study.

CONCLUSION: Epidural cortical stimulation of the left dorsolateral prefrontal cortex appears to be a safe and potentially efficacious neuromodulation approach for treatment-refractory major depressive disorder.”
“BACKGROUND: Heparin-induced thrombocytopenia type II (HIT II) correlates with a higher incidence of thromboembolic complications and unfavorable outcome.

The high content of intracellular proteolytic enzymes makes them

The high content of intracellular proteolytic enzymes makes them difficult cells to work with as they can degrade proteins of selleck chemicals llc potential interest. Here, we describe the benefits of heat treatment of neutrophils in reducing protein degradation for subsequent proteome analysis. Neutrophils isolated from four healthy volunteers were each divided into three aliquots and subjected to different preparation methods for 2-DE: (i) Heat treatment, (ii) resuspension in NP40 lysis buffer and (iii) resuspension in standard 2-DE lysis buffer. Representative spots found to be statistically significant between

groups (p<0.01) were excised and identified by LC-MS/MS, three of which were validated by immunoblotting. Heat-treated samples contained proteins in the high-molecular-weight range that were absent from NP40-treated

samples. Moreover, NP40-treated samples showed an increase in spot number and volume at lower molecular weights suggestive of protein degradation. Incorporating heat treatment into sample preparation resulted in the identification of proteins that may not have previously been detected due to sample degradation, thus leading to a more comprehensive 2-DE map of the human neutrophil proteome.”
“HIV viral load monitoring forms an essential part of the management of patients receiving antiretroviral therapy, but transport of samples without loss of RNA integrity may be problematic in resource limited settings. The use of plasma preparation tubes (PPT) which can be centrifuged to separate cellular components AZD4547 supplier before transport may provide a simple and cost-effective alternative to standard EDTA samples. We investigated whether PPT generated reliable results using the COBAS (R) AmpliPrep/COBAS (R) TaqMan (R) HIV-1 test version 2.0 (CAP/CTM HIV-1 v2.0). The mean difference between EDTA and PPT prepared samples (n = 261) was acceptable (log 0.04 copies/ml, percentage similarity CV 3.53%). PPT can Dolichyl-phosphate-mannose-protein mannosyltransferase be used for

viral load testing on the CAP/CTM HIV-1 v2.0. (c) 2012 Elsevier B.V. All rights reserved.”
“Designing an experiment for quantitative proteomic analysis is not a trivial task. One of the key factors influencing the success of such studies is the number of biological replicates included in the analysis. This, along with the measured variation will determine the statistical power of the analysis. Presented is a simple yet powerful analysis to determine the appropriate sample size required for reliable and reproducible results, based on the total variation (technical and biological). This approach can also be applied retrospectively for the interpretation of results as it takes into account both significance (p value) and quantitative difference (fold change) of the results.”
“Pseudotyped baculovirus has emerged as a promising vector for vaccine development and gene therapy. Alphaviruses, such as Semliki Forest virus (SFV), have also received considerable attention for use as expression vectors because of their self-replicating properties.