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Social relationships change across the lifespan as social networks narrow and motivational priorities shift to the present. Interestingly, aging is also associated with changes in executive function, including decision-making abilities, but it remains unclear how age-related changes in both domains interact to impact financial decisions involving other people. To study this problem, we recruited 50 human participants (N younger  = 26, ages 18-34; N older  = 24, ages 63-80) to play an economic trust game as the investor with three partners (friend, stranger, and computer) who played the role of investee. Investors underwent functional magnetic resonance imaging (fMRI) during the trust game while investees were seated outside of the scanner. Building on our previous work with younger adults showing both enhanced striatal responses and altered default-mode network (DMN) connectivity as a function of social closeness during reciprocated trust, we predicted that these relations would exhibit age-related differences. We found that striatal responses to reciprocated trust from friends relative to strangers and computers were blunted in older adults relative to younger adults, thus supporting our primary pre-registered hypothesis regarding social closeness. We also found that older adults exhibited enhanced DMN connectivity with the temporoparietal junction (TPJ) during reciprocated trust from friends compared to computers while younger adults exhibited the opposite pattern. Taken together, these results advance our understanding of age-related differences in sensitivity to social closeness in the context of trusting others., Competing Interests: Conflict of interest statement The authors have no conflicts to disclose., (Copyright © 2022. Published by Elsevier Inc.)

Capsular proteins from Helicoverpa armigera granulovirus (HaGV) have previously been shown to enhance H. armigera nucleopolyhedrovirus (HaSNPV) infection in H. armigera larvae. Yet, HaGV and HaS-NPV, as viable viruses, interfered with one another. In our study, we have examined the effects of co-infection of the slow-killing virus HaGV with the fast-killing virus Helicoverpa zea NPV (HzSNPV) on H. zea larvae. The mortality parameter measured was survival time. Virus stocks had 50% lethal concentrations of 3.2x10(-9) g HaGV-infected cadavers (GVC) (HaGV) and 32 occlusion bodies (HzSNPV) per cup. Average survival times were 16.8 and 5.5 days for larvae treated with HaGV and HzSNPV, respectively; death of HzSNPV-treated larvae was as early as 72 h posttreatment. In co-infection experiments in which larvae were treated concurrently with both viruses, the viruses competed in typical fashion for host resources. However, interference with disease progression in HzSNPV-fed larvae occurred even when HaGV was fed to larvae up to 36 h after the NPV, a time at which NPV infection should have been well established in host larvae. At death, co-infected larvae were observed microscopically to be filled with HaGV granules rather than HzSNPV polyhedra. The time study results imply that HaGV might be outcompeting HzSNPV by inhibiting its replication. We also observed that H. zea larvae treated with high dosages of HaGV (> or =3x10(-5) g GVC) were initially stunted but had survival times similar to those of larvae treated with lower dosages.

Characterization of an extrachromosomal element from an organism in the genus Spiroplasma is likely to be an essential step in the development of cloning vectors which replicate in these organisms. A restriction map for an 11-kb element, designated pCT-1, isolated from Spiroplasma taiwanese strain CT-1 (ATCC 43302) has been constructed using the restriction enzymes Bg/II, EcoRI, HincII, HindIII, HpaI, PstI, and XbaI. This element is distinct from any previously characterized spiroplasma virus or plasmid. pCT-1 has been cloned into the Escherichia coli vector pBR322 as a step in the development of a biphasic shuttle vector system.

Seven methods for the transfection of bacteria were compared and optimized for use in Spiroplasma citri strain HP using the spiroplasma virus SpV1 R8A2 B replicative form (RF). These methods included both chemical-mediated protocols [CaCl2, RbCl/CaCl2, polyethylene glycol (PEG)], liposome-mediated transfection, electroporation, freeze/thaw cycling, and natural competence. The best protocols were those which utilized PEG or electroporation, yielding transfection frequencies of 1.4 x 10(-4) and 9.1 x 10(-4) transfectants/colony-forming unit (CFU), respectively. For both of these protocols, transfection frequencies were higher using CsCl-purified, covalently closed, circular DNA. In the PEG-mediated protocol, Sigma 8000 brand PEG at a final concentration of 44%, and the presence of carrier DNA proved to be optimal with a PEG exposure time of 2 min. Using electroporation, a 1-2 ms pulse of a 6.5 kV/cm electric field was best; washing the host cell pellet prior to electroporation enhanced efficiencies by 50%. Linearization of the DNA resulted in lower transfection efficiencies by either method.

Several spiroplasmas (helical, motile mollicutes) were previously shown to contain extrachromosomal DNA (E-DNA) elements in the form of viruses (double-stranded viruses or the replicative form of single-stranded viruses) or plasmids. These elements are now being investigated as potential vectors for use in spiroplasma transformation systems. Described herein is the first extensive survey of spiroplasma E-DNA in 23 spiroplasma groups (30 strains), a study facilitated by improvements in protocols for E-DNA extraction. E-DNA elements were found in spiroplasmas associated with leafhoppers/plants (spiroplasma subgroups I-1, I-3, and I-8), other insects (subgroups I-2, I-5, I-6, and I-7 and groups IV and XXII), and ticks (subgroup I-4 and groups V and VI). Elements, maintained by passage with their host spiroplasmas, were often lost after extended passage. Whether the current distribution of E-DNA elements is indicative of historical or proximate factors is not known. Many elements (about 75%) from group I spiroplasmas hybridized with Spiroplasma citri viruses SpV1 or SpV3. Of the elements associated with other spiroplasma groups, none hybridized with either virus. These include Spiroplasma apis strains B31 (18 kb) and L89 (18 and 20 kb), S. mirum strains SMCA (20 kb) and Anderson (16 and 20 kb), group VI strain Y32 (7, 9, 10, and 16 kb), and group XXII strain CT-1 (8 kb). Several of these elements will be characterized and examined for their suitability as spiroplasma cloning vectors.