Problems of multi-species organisms: endosymbionts to holobionts

The organism is one of the fundamental concepts of biology and has been at the center of many discussions about biological individuality, yet what exactly it is can be confusing. The definition that we find generally useful is that an organism is a unit in which all the subunits have evolved to be highly cooperative, with very little conflict. We focus on how often organisms evolve from two or more formerly independent organisms. Two canonical transitions of this type—replicators clustered in cells and endosymbiotic organelles within host cells—demonstrate the reality of this kind of evolutionary transition and suggest conditions that can favor it. These conditions include co-transmission of the partners across generations and rules that strongly regulate and limit conflict, such as a fair meiosis. Recently, much attention has been given to associations of animals with microbes involved in their nutrition. These range from tight endosymbiotic associations like those between aphids and Buchnera bacteria, to the complex communities in animal intestines. Here, starting with a reflection about identity through time (which we call “Theseus’s fish”), we consider the distinctions between these kinds of animal–bacteria interactions and describe the criteria by which a few can be considered jointly organismal but most cannot

Chelated Assisted Metal-Mediated N–H Bond Activation of β‑Lactams: Preparation of Irida‑, Rhoda‑, Osma‑, and Ruthenatrinems

2-Azetidinones substituted with pyridine (<b>2a</b>), quinoline (<b>2b</b>), isoquinoline (<b>2c</b>), imidazole (<b>2d</b>), and benzimidazole (<b>2e</b>) at the 4-position of the four-membered ring have been prepared in order to synthesize tribactams containing a transition metal and its associated ligands, L_<i>n</i>M, at the 2-position of the tricyclic skeleton. The developed procedure is compatible with a wide range of transition-metal starting complexes. Thus, the iridium and rhodium dimers [M­(η⁵-C₅Me₅)­Cl₂]₂ react with <b>2a</b>–<b>e</b>, in the presence of sodium acetate, to afford irida- and rhodatrinems (<b>1a</b>–<b>j</b>) containing the half-sandwich d⁶ metal fragments M­(η⁵-C₅Me₅)Cl (M = Ir, Rh). The reactions of [M­(μ-OMe)­(η⁴-COD)]₂ (M = Ir, Rh) with <b>2a</b> lead to irida- and rhodatrinems (<b>1k</b>,<b>l</b>) with the d⁸ moieties M­(η⁴-COD). The coordination sphere and oxidation state of the metal center in these compounds can be modified, without affecting the 2-azetidinone backbone, by means of substitution and oxidative addition reactions. As a proof of concept, metallatrinems with the M­(CO)₂ (M = Ir (<b>1m</b>), Rh (<b>1n</b>)) and Ir­(Me)­I­(CO)₂ (<b>1o</b>) units are also reported. Osmatrinems <b>1p</b>,<b>q</b> containing the d⁴ metal fragment OsH₃(PⁱPr₃)₂ have been obtained starting from the d² hexahydride OsH₆(PⁱPr₃)₂, by reaction with <b>2a</b>,<b>b</b>, whereas the treatment of the tetrahydroborate complexes MH­(η²-H₂BH₂)­(CO)­(PⁱPr₃)₂ (M = Os, Ru) with <b>2a</b> yields osma- and ruthenatrinems (<b>1r</b>,<b>s</b>) containing six-coordinate bis­(phosphine) d⁶ metal fragments. The IR stretching frequency of the lactamic carbonyl, the bent angle between the five- and four-membered rings of the tricycle, and the N–CO bond length in the lactamic ring are clearly infuenced by the L_<i>n</i>M fragment