Scanning transmission electron microscopy (STEM) of specimens in liquid, so-called Liquid STEM, is capable of imaging the individual subunits of macromolecular complexes in whole eukaryotic cells in liquid. This paper discusses this new microscopy modality within the context of state-of-the-art microscopy of cells. The principle of operation and equations for the resolution are described. The obtained images are different from those acquired with standard transmission electron microscopy showing the cellular ultrastructure. Instead, contrast is obtained on specific labels. Images can be recorded in two ways, either via STEM at 200 keV electron beam energy using a microfluidic chamber enclosing the cells, or via environmental scanning electron microscopy at 30 keV of cells in a wet environment. The first series of experiments involved the epidermal growth factor receptor labeled with gold nanoparticles. The labels were imaged in whole fixed cells with nanometer resolution. Since the cells can be kept alive in the microfluidic chamber, it is also feasible to detect the labels in unfixed, live cells. The rapid sample preparation and imaging allows studies of multiple whole cells.

Nine prepubertal gilts (JunMu No. 1) were randomly allocated into three groups (n=3) and fed with a high-energy diet (Group H), a low-energy diet (Group L), or a moderate-energy diet (Group M) for 14 days. Free access to water was provided throughout the research period. Ovaries and uteri were collected after the energy treatments, and processed for determination of the absolute quantities of insulin-like growth factor receptor (IGF-1R) and epidermal growth factor receptor (EGFR) mRNA, using real-time polymerase chain reaction (PCR). The expression of IGF-1R and EGFR mRNA in ovaries and uteri was significantly ranked as: Group H>Group M>Group L (P<0.05). This result suggests that high energy intake markedly enhanced the ovarian and uterine expression of IGF-1R and EGFR in prepubertal gilts, whereas insufficient energy intake markedly inhibited such expression. IGF-1R and EGFR may be involved in mediating the effects of energy intake on the development of the reproductive system in prepubertal gilts.

The role of estradiol and the estrogen receptor (ER-α) in the etiology of breast cancer have long been appreciated. This understanding has been complicated by two discoveries in the 1990s: (1) a second estrogen receptor (ER-β) whose expression pattern and activity overlap with but are distinct from those of ER-α; and (2) a pool of ERs located at the plasma membrane. This plasma membrane-localized ER constitutes a distinct pool of receptors whose protein interactions, signaling mechanisms, and cellular functions are not the same as that of the cytoplasmic- and nuclear-localized ER and are not as well understood. Here, we will consider the structure and function of the membrane-localized ER protein. We will then discuss what is known about the role of the membrane ER in the development and its implications for breast cancer treatment.