C-terminal labelling of beta-casein

This paper is the first to report specific labelling of a native protein at its C-terminal end by carboxypeptidase Y-catalyzed transpeptidation between beta-casein and tritiated Phe amide. A tryptic digest of the radiolabelled protein was resolved by reversed-phase HPLC and a single labelled peptide was isolated therefrom. Sequence determination and FAB mass spectrometry showed that the last 2 residues (Val-209, Ile-208) of beta-casein had been deleted and Ile 207 substituted by Phe, deamidation presumably occurring after transpeptidation. Identical results were obtained by transpeptidating the isolated C-terminal tryptic heptapeptide (203-209) of native beta-casein.     

Demonstration and ontogenesis in the rat of a serum protein analogous to human thyroxine binding globulin

It has been reported evidence based on equilibrium binding, electrophoretic, immunoelectrophoretic studies, that the rat possesses a major high affinity thyroid hormone binding protein, with an electrophoretic mobility and binding properties similar to those of the human thyroxine binding globulin (TBG). It is shown that in the sera of postnatal developing animals, between 3 and 21 days, the thyroxine (T4) and the triiodothyronine (T3) binding activities increase up to 10 times over adult or foetal levels, due to a high transient post-natal surge of the rat TBG. In the adult serum, the TBG persists in decreased amounts: it then yields the predominant role as T4 carrier to the thyroid binding prealbumin (TBPA), but retains the major role as binder of T3, i.e. of the biologically active thyroid hormone.     

Binding activities of thyroxine binding globulin versus thyroxine binding prealbumin in rat sera: differential modulation by thyroid hormone ligands, oleic acid and pharmacological drugs

We use gel equilibration and electrophoretic techniques to compare the binding properties of thyroxine binding globulin and thyroxine binding prealbumin in rat sera. The evidence indicates that TBG bears the serum lowest capacity highest affinity sites for thyroxine (T4) and triiodothyronine (T3) (Ka1 greater than or equal to 10(9) M-1) as well as weaker saturable T3 sites (Ka2 approximately 10(8) M-1). TBPA bears for T4 only Ka2 approximately 10(8) M-1 sites and for T3 only Ka approximately 10(6) M-1 sites. Consistent with these parameters are the specific responses of TBG and TBPA binding activities to varying serum concentrations of T4, T3, oleic acid, the drugs diphenylhydantoin or salicylate. The primary attack of these compounds is aimed at TBG. Small T4, oleate or DPH doses chase the TBG-bound T4 to TBPA, high doses of T4 or oleate but not of DPH inhibiting the T4 binding to both proteins. In the T3-serum interactions, all tested compounds displace the TBG-bound hormone without chasing it to TBPA. The high reactivity of TBG sites designates the protein as crucially involved in modulating the free vs bound serum levels of T4 and T3 against physiological or pathological variations of binding competitors.     

Mode of Action of Pesticin

The mode of action of pesticin, a bacteriocin produced by many strains of Pasturella pestis, was studied. Pesticin action on macromolecular synthesis of a sensitive strain of Escherichia coli, strain , was found to have features similar to those of colicin E2-317 acting on the same strain. After exposure to pesticin, deoxyribonucleic acid synthesis was arrested and ribonucleic acid was degraded, but little effect was observed on protein synthesis. Pesticin, like colicin E2-317, induced lysogenic E. coli (P1), but, unlike the colicin, was active in the presence of dinitrophenol. Trypsin was found to reverse pesticin action up to 15 min after its addition at 40 C to E. coli . Pesticin action was studied on three sensitive bacterial strains, P. pestis 2C, P. pseudotuberculosis, and E. coli strain , which vary widely in their optimal growth temperature. P. pestis grows best at 29 C, P. pseudotuberculosis at 37 C, and E. coli at 40 C. It was found that pesticin action on all three strains was optimal at 40 C. Whereas the titer of pesticin was the same on all three strains when determined on agar, E. coli was the most sensitive to pesticin action in broth. No action of pesticin in broth on P. pseudotuberculosis was observed unless Ca ions were added. The effect was not immediate; that is, the cells had to be grown in a medium containing Ca⁺⁺ before they displayed sensitivity to pesticin.     

Vectors permitting visual monitoring of simple transposition events

The construction and use of two novel transposon(Tn)-delivery vectors is described. These vectors carry Inc.W or Inc.N broad-host-range transfer functions cloned next to the narrow-host-range replicon of pBR329. The host specificities of pSLX10 and pSLX23 both complement and extend the host specificities of existing Tn delivery vectors. Plasmids pSLX10 and pSLX23 were shown to transfer at high frequency in intergeneric matings. The lux genes which are present on each vector permit the visual monitoring of transconjugants which have retained a Tn element, but are devoid of plasmid molecules. pSLX10 and pLSX23 were efficiently used to generate a range of auxotrophic mutants in various strains of Pseudomonas as well as to clone genes from Serratia liquefaciens. These vectors may have general applicability to identify and clone genes in a wide range of Gram-negative bacteria.     

Mitogenic response of rat lung and tracheal epithelial cells in monolayer primary cultures—Modulation of TNF-α expression

Epithelial cells isolated from rat lung and trachea were grown on monolayers and their response to a number of hormones and growth factors were studied. Maximum proliferative response in serum containing media was observed when insulin, cholera toxin and cortisol were present together. However, these additives when present independently showed a marginal response. The synergism, due to these factors in promoting growth was seen very early in culture (day 4) as shown by thymidine labelling studies, On examining the indices of early mitogenesis, such as the expression ofc-myc, our data suggests that these factors stimulate the expression ofc-myc within 4 h. With respect to expression of TNF-α mRNA, this study suggests a possible modulation of TNF-α expression in response to these mitogens that stimulate proliferation maximally. Whether this expression of TNF-α by these epithelial cells is due to a maximal proliferative stimulus and/or is an early step in the cascade of intracellular signalling events is to be investigated in detail.     

Three research priorities for just and sustainable urban systems: Now is the time to refocus

Now is the time to refocus efforts in urban research and design. A changing climate and extreme weather events are presenting unique challenges to urban systems around the world. These challenges illuminate the social barriers that accompany disruptive events such as resource inequities and injustices. In this perspective, we provide three research priorities for just and sustainable urban systems that help to address these matters. The three research priorities are: (1) social equity and justice, (2) circularity, and (3) digital twins. Conceptual context and future research directions are provided for each. For social equity and justice, the future directions are mandatory equity analysis and inclusionary practices, understanding and reconciling historical injustices, and intentional integration with diverse community stakeholders. For circularity applications, they are better metrics for integration, more robust evaluation frameworks, and dynamic modeling at multiple spatial and temporal scales. Future directions for digital twins include developing principles to reduce complexity, integrating model and system components, and reducing barriers to data access. These research priorities are core to meeting several of the United Nations Sustainable Development Goals (i.e., 1—No Poverty, 8—Decent Work and Economic Growth, 10—Reduced Inequalities, and 11—Sustainable Cities and Communities). Useful social and technical matters are discussed throughout, where we highlight the importance of prioritizing localized research efforts, provide guidance for community-engaged research and co-development practices, and explain how these priorities interact to align with the evolving field of industrial ecology.