Thrust production and chordal flexion of the flukes of bottlenose dolphins performing tail stands at different efforts.

Dolphins have become famous for their ability to perform a wide variety of athletic and acrobatic behaviors including high-speed swimming, maneuverability, porpoising and tail stands. Tail stands are a behavior where part of the body is held vertically above the water's surface, achieved through thrust produced by horizontal tail fluke oscillations. Strong, efficient propulsors are needed to generate the force required to support the dolphin's body weight, exhibiting chordwise and spanwise flexibility throughout the stroke cycle. To determine how thrust production, fluke flexibility and tail stroke kinematics vary with effort, six adult bottlenose dolphins (Tursiops truncatus) were tested at three different levels based on the position of the center of mass (COM) relative to the water's surface: low (COM below surface), medium (COM at surface) and high (COM above surface) effort. Additionally, fluke flexibility was measured as a flex index (FI=chord length/camber length) at four points in the stroke cycle: center stroke up (CU), extreme top of stroke (ET), center stroke down (CD) and extreme bottom of stroke (EB). Video recordings were analyzed to determine the weight supported above the water (thrust production), peak-to-peak amplitude, stroke frequency and FI. Force production increased with low, medium and high efforts, respectively. Stroke frequency also increased with increased effort. Amplitude remained constant with a mean 33.8% of body length. Significant differences were seen in the FI during the stroke cycle. Changes in FI and stroke frequency allowed for increased force production with effort, and the peak-to-peak amplitude was higher compared with that for horizontal swimming.

In Vitro and In Vivo Evidence towards Fibronectin's Protective Effects against Prion Infection.

A distinctive signature of the prion diseases is the accumulation of the pathogenic isoform of the prion protein, PrPSc, in the central nervous system of prion-affected humans and animals. PrPSc is also found in peripheral tissues, raising concerns about the potential transmission of pathogenic prions through human food supplies and posing a significant risk to public health. Although muscle tissues are considered to contain levels of low prion infectivity, it has been shown that myotubes in culture efficiently propagate PrPSc. Given the high consumption of muscle tissue, it is important to understand what factors could influence the establishment of a prion infection in muscle tissue. Here we used in vitro myotube cultures, differentiated from the C2C12 myoblast cell line (dC2C12), to identify factors affecting prion replication. A range of experimental conditions revealed that PrPSc is tightly associated with proteins found in the systemic extracellular matrix, mostly fibronectin (FN). The interaction of PrPSc with FN decreased prion infectivity, as determined by standard scrapie cell assay. Interestingly, the prion-resistant reserve cells in dC2C12 cultures displayed a FN-rich extracellular matrix while the prion-susceptible myotubes expressed FN at a low level. In agreement with the in vitro results, immunohistopathological analyses of tissues from sheep infected with natural scrapie demonstrated a prion susceptibility phenotype linked to an extracellular matrix with undetectable levels of FN. Conversely, PrPSc deposits were not observed in tissues expressing FN. These data indicate that extracellular FN may act as a natural barrier against prion replication and that the extracellular matrix composition may be a crucial feature determining prion tropism in different tissues.

BAD regulates mammary gland morphogenesis by 4E-BP1-mediated control of localized translation in mouse and human models.

Elucidation of non-canonical protein functions can identify novel tissue homeostasis pathways. Herein, we describe a role for the Bcl-2 family member BAD in postnatal mammary gland morphogenesis. In Bad3SA knock-in mice, where BAD cannot undergo phosphorylation at 3 key serine residues, pubertal gland development is delayed due to aberrant tubulogenesis of the ductal epithelium. Proteomic and RPPA analyses identify that BAD regulates focal adhesions and the mRNA translation repressor, 4E-BP1. These results suggest that BAD modulates localized translation that drives focal adhesion maturation and cell motility. Consistent with this, cells within Bad3SA organoids contain unstable protrusions with decreased compartmentalized mRNA translation and focal adhesions, and exhibit reduced cell migration and tubulogenesis. Critically, protrusion stability is rescued by 4E-BP1 depletion. Together our results confirm an unexpected role of BAD in controlling localized translation and cell migration during mammary gland development.

Fasting and refeeding induces changes in the mouse hepatic lipid droplet proteome.

During fasting, the liver increases lipid storage as a mean to reserve and provide energy for vital cellular functions. After re-feeding, hepatocytes rapidly decrease the amount of triacylglycerol that is stored in lipid droplets (LDs), visible as the size of hepatic LDs significantly decreases after re-feeding. Little is known about the changes in the liver LD proteome that occur during the fasting/re-feeding transition. This study aimed to investigate the hepatic LD proteome in fasted and re-fed conditions in the mouse. Using label-free LC-MS/MS analysis the relative abundance of 817 proteins was determined in highly purified LDs. Comparative analysis for differential protein abundance with respect to feeding states revealed 130 with higher abundance in LDs from fasted mice and 31 in LDs from re-fed mice. Among proteins observed to have higher abundance on LDs in the fasted state we found perilipin-5, and several mitochondrial and peroxisomal marker proteins, supporting the role of LDs in the provision of substrates for fatty acid oxidation. Proteins of higher abundance upon re-feeding included several peroxisomal and mitochondrial marker proteins and expand our understanding of the dynamic nature of the hepatic LD proteome according to the energetic requirements of the cell. BIOLOGICAL SIGNIFICANCE: Proteomic investigations have been revealing the complexities and dynamics of cellular LDs from a variety of cell types. As these sub-cellular structures are truly dynamic in nature, our investigations reveal that simply the feeding state of an animal leads to significant changes to the protein composition of LDs and suggest a variety of dynamic interactions with other cellular organelles, such as the mitochondria and peroxisomes. As such, the experimental design for investigations of this cellular structure must consider this dynamic baseline. Lastly our analysis on global protein abundance has revealed the unforeseen high abundance of murine major urinary proteins associated with hepatic lipid droplets, which warrants further investigations.

Proteomic characterization of EL4 lymphoma-derived tumors upon chemotherapy treatment reveals potential roles for lysosomes and caspase-6 during tumor cell death in vivo.

The murine mouse lymphoblastic lymphoma cell line (EL4) tumor model is an established in vivo apoptosis model for the investigation of novel cancer imaging agents and immunological treatments due to the rapid and significant response of the EL4 tumors to cyclophosphamide and etoposide combination chemotherapy. Despite the utility of this model system in cancer research, little is known regarding the molecular details of in vivo tumor cell death. Here, we report the first in-depth quantitative proteomic analysis of the changes that occur in these tumors upon cyclophosphamide and etoposide treatment in vivo. Using a label-free quantitative proteomic approach a total of 5838 proteins were identified in the treated and untreated tumors, of which 875 were determined to change in abundance with statistical significance. Initial analysis of the data reveals changes that may have been predicted, such as the downregulation of ribosomes, but demonstrates the robustness of the dataset. Analysis of the dataset also reveals the unexpected downregulation of caspase-3 and an upregulation of caspase-6 in addition to a global upregulation of lysosomal proteins in the bulk of the tumor.

Determinants of rodent longevity in the chaperone-protein degradation network.

Proteostasis is an integral component of healthy aging, ensuring maintenance of protein structural and functional integrity with concomitant impact upon health span and longevity. In most metazoans, increasing age is accompanied by a decline in protein quality control resulting in the accrual of damaged, self-aggregating cytotoxic proteins. A notable exception to this trend is observed in the longest-lived rodent, the naked mole-rat (NMR, Heterocephalus glaber) which maintains proteostasis and proteasome-mediated degradation and autophagy during aging. We hypothesized that high levels of the proteolytic degradation may enable better maintenance of proteostasis during aging contributing to enhanced species maximum lifespan potential (MLSP). We test this by examining proteasome activity, proteasome-related HSPs, the heat-shock factor 1 (HSF1) transcription factor, and several markers of autophagy in the liver and quadriceps muscles of eight rodent species with divergent MLSP. All subterranean-dwelling species had higher levels of proteasome activity and autophagy, possibly linked to having to dig in soils rich in heavy metals and where underground atmospheres have reduced oxygen availability. Even after correcting for phylogenetic relatedness, a significant (p < 0.02) positive correlation between MLSP, HSP25, HSF1, proteasome activity, and autophagy-related protein 12 (ATG12) was observed, suggesting that the proteolytic degradation machinery and maintenance of protein quality play a pivotal role in species longevity among rodents.

A review of the federal guidelines that inform and influence relationships between physicians and industry.

The effective delivery and continued advancement of health care is critically dependent on the relationship between physicians and industry. The private sector accounts for 60% of the funding for clinical research and more than 50% of the funding sources for physician education. The nature of the physician-industry relationship and the role of the physician as a gatekeeper for health care make this association vulnerable to abuse if certain safeguards are not observed. This article will review the current federal guidelines that affect the physician-industry relationship and highlight several illustrative cases to show how the potential for abuse can subvert this relationship. The recommendations and "safe harbors" that have been designed to guide business relationships in health care are discussed.