Cell survival and multiplication

Abstract There are clear similarities in the control mechanisms for cell survival and multiplication in the two eukaryotes, the ciliate Tetrahymena thermophila and the yeast, Saccharomyces cerevisiae . Cell multiplication in both organisms is activated by the same compounds (phorbol esters, diacylglycerol, tetrapyrroles, etc.). These compounds also affect cell multiplication and other activities in mammalian cell systems. This homology in control mechanisms in two distinct groups of unicellular eukaryotes on the one hand, and in cells from multicellular animals on the other, leads us to propose that these cytoplasmic control mechanisms for cell survival and multiplication originated in the unicellular eukaryotes.     

The evolution of large body size in orangutans: A model for hominoid divergence

Recent Miocene fossil discoveries of large hominoids resemble orangutans. Since the evolution of large body size was functionally related to a powerful masticatory system in Miocene ape radiations, a better understanding of adaptations in extant orangutans will be informative of hominoid evolution. It is suggested here, based on the behavioral ecology of extant orangutans, that foraging energetics and large body size are tied to a dietary shift that provided access to and utilization of resources not generally available to other primates.     

Targeted binding of PEG‐lipid modified polymer ultrasound contrast agents with tiered surface architecture

In order for site‐directed polymer ultrasound contrast agents (UCAs) to provide acoustic enhancement at disease sites to distinguish normal tissue from diseased tissue, the surface of these agents must be functionalized with mixtures of grafted polymers. Here a combination of longer liganded polyethylene glycol (PEG)‐lipids and shorter unliganded PEG‐lipids were introduced into the oil phase of a modified solvent evaporation double emulsion method for preparing UCAs. UCAs with different lengths of both liganded and unliganded lipids were imaged under 7.5 MHz ultrasound. The B‐mode image brightness of the mixed PEG‐lipid UCAs was within 1 dB the brightness of the unliganded surface. After 15 min of continuous insonation, 70% of the contrast signal remained. The peptide arginine–glycine–aspartic acid (RGD) was added to the surface of these UCAs through a biotin–avidin linkage and binding was assessed under static and shear conditions. Binding was significant after 30 min of static incubation and the adherence of the UCA increased under shear flow from 3 UCA/cell (static) to 5 UCA/cell (shear). Biotechnol. Bioeng. 2010; 106: 501–506. © 2010 Wiley Periodicals, Inc.     

Primary cilia: turning points in establishing their ubiquity,sensory role and the pathological consequences of dysfunction

For over 20 years it has finally become accepted that primary cilia are without doubt important cellular organelles, involved in signalling both intrinsically and extrinsically. The consequences of their agenesis, incorrect assembly and dysfunction only began to be fully appreciated after 2000, although this had been demonstrable over the previous two decades. Before 1980, biologists at large thought the organelle rudimentary or vestigial; how a well-developed cilium could be so slated beggars belief. Many pathological conditions have implicated the primary cilium as either a major or contributing factor, ranging from kidney malfunction (e.g. polycystic kidney disease) to mental aberrations. However, the questions of how the recognition of their prevalence, their sensory function, and their pathological involvement finally emerged as substantiated and verifiable facts needs to be addressed because what happened before the 1980s, and then notably between 1980 and 2000, can help guide research towards answering further questions on these issues. Here the intention is to focus on the salient findings (the turning points) that brought about changes in our knowledge of primary cilia. The literature on them is growing fast, with the total moving towards 20,000 reports, of which > 60% have been published in the last decade. PubMed indicates that nearly 1000 papers were published in 2020 alone. We also have to appreciate that the primary cilium can assume many different forms, each of which means that there must be many genes responsible for their development and final structure. This also suggests that there are many more functions than are currently known in both their sensory reception and signalling properties, probably for many highly specialised purposes. Malfunctioning in any of these roles will undoubtedly uncover further pathological conditions.