An operational manpower analysis of the RQ-8 Fire Scout Vertical Take-Off Unmanned Aerial Vehicle (VTUAV)

In August of 2001 the Secretary of the Navy announced the Navy would expand the work and experimentation in unmanned vehicle systems. After the events of September 11 this was accelerated with the increased urgency to combat terrorism and asymmetric threats. The U.S. Navy is currently undergoing testing and evaluation of the Fire Scout Vertical Take-Off Unmanned Aerial Vehicle (VTUAV) and its integration into the fleet. An in depth analysis of the Fire Scout's manpower requirements is necessary as part of total force integration. At the present time, the Navy only utilizes aviation ratings by requirement and assignment as unmanned aerial system operators, unlike the Army and Marine Corps. Therefore, the Littoral Combat Ship manpower requirements exceed the Navy's target of 25 persons for the combined RQ-8B and SH-60 air detachment. Analysis shows a possible remedy to this problem is to allow non-aviation ratings the opportunity to operate the Fire Scout. This change in policy and occupational standards would generate greater operational capability and personnel flexibility for this newly acquired air ship and surface platform. Specifically, occupational research showed the Aviation Administrationman (AZ) rating is no more qualified to operate a Fire Scout VTUAV than the Operations Specialist (OS) rating. In fact, it can be argued that an OS is better qualified according to occupational standards to operate the Fire Scout. Therefore, one of the recommendations of this research is to add Operational Specialist as a source rating to NECs 8363 and 8364 immediately.http://archive.org/details/anoperationalman109453208US Navy (USN) author.Approved for public release; distribution is unlimited

Deaminase-Independent Inhibition of Parvoviruses by the APOBEC3A Cytidine Deaminase

The APOBEC3 proteins form a multigene family of cytidine deaminases with inhibitory activity against viruses and retrotransposons. In contrast to APOBEC3G (A3G), APOBEC3A (A3A) has no effect on lentiviruses but dramatically inhibits replication of the parvovirus adeno-associated virus (AAV). To study the contribution of deaminase activity to the antiviral activity of A3A, we performed a comprehensive mutational analysis of A3A. By mutation of non-conserved residues, we found that regions outside of the catalytic active site contribute to both deaminase and antiviral activities. Using A3A point mutants and A3A/A3G chimeras, we show that deaminase activity is not required for inhibition of recombinant AAV production. We also found that deaminase-deficient A3A mutants block replication of both wild-type AAV and the autonomous parvovirus minute virus of mice (MVM). In addition, we identify specific residues of A3A that confer activity against AAV when substituted into A3G. In summary, our results demonstrate that deaminase activity is not necessary for the antiviral activity of A3A against parvoviruses

Parvovirus Minute Virus of Mice Induces a DNA Damage Response That Facilitates Viral Replication

Infection by DNA viruses can elicit DNA damage responses (DDRs) in host cells. In some cases the DDR presents a block to viral replication that must be overcome, and in other cases the infecting agent exploits the DDR to facilitate replication. We find that low multiplicity infection with the autonomous parvovirus minute virus of mice (MVM) results in the activation of a DDR, characterized by the phosphorylation of H2AX, Nbs1, RPA32, Chk2 and p53. These proteins are recruited to MVM replication centers, where they co-localize with the main viral replication protein, NS1. The response is seen in both human and murine cell lines following infection with either the MVMp or MVMi strains. Replication of the virus is required for DNA damage signaling. Damage response proteins, including the ATM kinase, accumulate in viral-induced replication centers. Using mutant cell lines and specific kinase inhibitors, we show that ATM is the main transducer of the signaling events in the normal murine host. ATM inhibitors restrict MVM replication and ameliorate virus-induced cell cycle arrest, suggesting that DNA damage signaling facilitates virus replication, perhaps in part by promoting cell cycle arrest. Thus it appears that MVM exploits the cellular DNA damage response machinery early in infection to enhance its replication in host cells

Interactions between Mei4, Rec114, and other proteins required for meiotic DNA double-strand break formation in Saccharomyces cerevisiae.

In most sexually reproducing organisms, meiotic recombination is initiated by DNA double-strand breaks (DSBs) formed by the Spo11 protein. In budding yeast, nine other proteins are also required for DSB formation, but roles of these proteins and interactions among them are poorly understood. We report here further studies of the behaviors of these proteins. Consistent with other studies, we find that Mei4 and Rec114 bind to chromosomes from leptonema through early pachynema. Both proteins showed only limited colocalization with the meiotic cohesin subunit Rec8, suggesting that Mei4 and Rec114 associated preferentially with chromatin loops. Rec114 localization was independent of other DSB factors, but Mei4 localization was strongly dependent on Rec114 and Mer2. Systematic deletion analysis identified protein regions important for a previously described two-hybrid interaction between Mei4 and Rec114. We also report functional characterization of a previously misannotated 5′ coding exon of REC102. Sequences encoded in this exon are essential for DSB formation and for Rec102 interaction with Rec104, Spo11, Rec114, and Mei4. Finally, we also examined genetic requirements for a set of previously described two-hybrid interactions that can be detected only when the reporter strain is induced to enter meiosis. This analysis reveals new functional dependencies for interactions among the DSB proteins. Taken together, these studies support the view that Mei4, Rec114, and Mer2 make up a functional subgroup that is distinct from other subgroups of the DSB proteins: Spo11-Ski8, Rec102-Rec104, and Mre11-Rad50-Xrs2. These studies also suggest that an essential function of Rec102 and Rec104 is to connect Mei4 and Rec114 to Spo11

DNMT3A mutations promote anthracycline resistance in acute myeloid leukemia via impaired nucleosome remodeling

Although the majority of acute myeloid leukemia (AML) patients initially respond to chemotherapy, many patients subsequently relapse; the mechanistic basis for AML persistence following chemotherapy has not been delineated. Recurrent somatic mutations in DNA methyltransferase 3A (DNMT3A), most frequently at arginine 882 (DNMT3A(mut)), are observed in AML(1–3) and in individuals with clonal hematopoiesis in the absence of leukemic transformation(4,5). DNMT3A(mut) AML patients have an inferior outcome when treated with standard-dose daunorubicin-based induction chemotherapy(6,7), suggesting that DNMT3A(mut) cells persist and drive relapse(8). Here we show that Dnmt3a(mut) induces hematopoietic stem cell (HSC) expansion, cooperates with Flt3(ITD) and Npm1(c) to induce AML in vivo, and promotes resistance to anthracycline chemotherapy. In AML patients, DNMT3A(R882) mutations predict for minimal residual disease (MRD), underscoring their role in AML chemoresistance. DNMT3A(mut) cells show impaired nucleosome eviction and chromatin remodeling in response to anthracyclines, resulting from attenuated recruitment of histone chaperone SPT-16 following anthracycline exposure. This defect leads to an inability to sense and repair DNA torsional stress, which results in increased mutagenesis. Our studies identify a critical role for DNMT3A(R882) mutations in driving AML chemoresistance, and highlight the importance of chromatin remodeling in response to cytotoxic chemotherapy