This document provides methods and materials for treating aging. For example, a mammal having, or at risk for developing, an age-related impairment (e.g., age-related cognitive decline) can be treated by increasing the level of one or more myokine polypeptides (e.g., one or more Klotho polypeptides) within cells within the mammal. This document also provides methods and materials for increasing the ability of muscle progenitor cells to regenerate muscle cells by increasing the level(s) of one or more myokine polypeptides (e.g., an α-Klotho polypeptide) within a muscle progenitor cell.

Provided herein are methods and compositions for highly precise base editing and single strand nicking. In particular, provided herein are methods for producing a genetically modified cell where the methods employ a universal, highly precise base editor or staggered Cas9 editor for precise base editing with minimal off-target or bystander effects.

Methods are provided that, for example, include (a) combining ssDNA containing a modified nucleotide (e.g., a ssDNA with a modified nucleotide proximate to its 5′ end) with a DNA cleavage enzyme capable of cleaving the ssDNA at the modified nucleotide (e.g., to generate a first ssDNA fragment having a 3′OH and a second ssDNA fragment having the modified nucleotide); wherein the ratio of enzyme to DNA substrate is less than 1:1 molar ratio (m/m); and (b) cleaving at least 95% of the ssDNA at the modified nucleotide. In some embodiments, a method may comprise (a) combining (i) a ssDNA comprising a modified nucleotide (e.g., proximate to its 5′ end) with (ii) a DNA cleavage enzyme capable of cleaving the ssDNA at the modified nucleotide (e.g., to generate (after cleavage) a first ssDNA fragment having a 3′OH and a second ssDNA fragment comprising the modified nucleotide) wherein the ratio of enzyme to DNA substrate is less than 1:1 molar ratio and cleaving at least 95% of the ssDNA at the modified nucleotide. In some embodiments, methods provided herein may include (a) combining (i) a ssDNA (1) immobilized on a substrate and (2) comprising a modified nucleotide with (ii) a ssDNA cleaving enzyme capable of cleaving the ssDNA at the modified nucleotide (e.g., to generate (after cleavage) a first ssDNA fragment having a 3′OH and a second ssDNA fragment comprising the modified nucleotide) ; and (b) cleaving the immobilized ssDNA to release the second single stranded DNA fragment from the substrate. At least 95% (m/m) of an ssDNA comprising a modified nucleotide may be cleaved in less than 60 minutes.

The present invention provides a method for modifying a targeted site of a double-stranded DNA in a cell, the method including a step of bringing a complex in which a nucleic acid sequence-recognizing module that specifically binds to a selected target nucleotide sequence in a double-stranded DNA and a nucleic acid base converting enzyme or DNA glycosylase are linked, and a donor DNA containing an insertion sequence into contact with said double-stranded DNA, to substitute the targeted site with the insertion sequence, or insert the insertion sequence into said targeted site, without cleaving at least one strand of said double-stranded DNA in the targeted site.

The present invention provides a method for modifying a targeted site of a double-stranded DNA in a cell, the method including a step of bringing a complex in which a nucleic acid sequence-recognizing module that specifically binds to a selected target nucleotide sequence in a double-stranded DNA and a nucleic acid base converting enzyme or DNA glycosylase are linked, and a donor DNA containing an insertion sequence into contact with said double-stranded DNA, to substitute the targeted site with the insertion sequence, or insert the insertion sequence into said targeted site, without cleaving at least one strand of said double-stranded DNA in the targeted site.

The present invention relates to microbial production of nicotinamide mononucleotide (NMN), nicotinamide riboside (NR), and nicotinamide adenine dinucleotide (NAD) using a genetically modified bacterium.

Metabolically-engineered yeast strains are provided. such as metabolically-engineered Saccharomyces cerevisiaestrains. producing high amounts of at least one. preferably all four natural cytokinins: trans-zeatin (tZ), trans-zeatin riboside (tZR). isopentenyladenine (iP) and isopenteny ladenine riboside (iPR).

Compositions of the invention comprise 8-oxoguanine glycosylase (OGG1) and SIRT6 activating peptide G-A-G-V-S-A-E-NH.sub.2. Compositions of the invention exhibit anti-aging effects by promoting the repair of skin cell DNA and/or by protecting skin cell DNA from UV damage.

N-glycosylation profiling of glycoprotein biotherapeutics is an essential step in each phase of product development in the biopharmaceutical industry. For example, during clone selection hundreds of clones should be analyzed quickly from limited amounts of samples. On the other hand, identification of disease related glycosylation alterations can serve as early indicators for various pathological conditions in the biomedical field. We describe an improved packed bed column PNGase F functionalized column reactor. The reactor may be packed into a pipette tip column. In some embodiments, a second column or mixed stationary phase may be packed into the column to capture and purify the cleaved glycan prior to analysis. Complete N-glycan removal can be obtained in 10 minutes from all major N-linked glycoprotein types. The approach can be readily applied to automated sample preparation systems, such as liquid handling robots.

Compositions of the invention comprise 8-oxoguanine glycosylase (OGG1) and SIRT6 activating peptide G-A-G-V-S-A-E-NH.sub.2. Compositions of the invention exhibit anti-aging effects by promoting the repair of skin cell DNA and/or by protecting skin cell DNA from UV damage.