Cells from virtually all organisms respond to a variety of stresses by the rapid synthesis of a highly conserved set of polypeptides termed heat shock proteins (HSPs). The precise functions of HSPs are unknown, but there is considerable evidence that these stress proteins are essential for survival at both normal and elevated temperatures. HSPs also appear to play a critical role in the development of thermotolerance and protection from cellular damage associated with stresses such as ischemia, cytokines, and energy depletion. These observations suggest that HSPs play an important role in both normal cellular homeostasis and the stress response. This mini-review examines recent evidence and hypotheses suggesting that the HSPs may be important modifying factors in cellular responses to a variety of physiologically relevant conditions such as hyperthermia, exercise, oxidative stress, metabolic challenge, and aging.

https://www.physiology.org/doi/pdf/10.1152/japplphysiol.01267.2001

Invited Review: Heat shock proteins: modifying factors in physiological stress responses and acquired thermotolerance

Flattened, rotating disks of cool dust and gas extending for tens to hundreds of astronomical units are found around almost all low-mass stars shortly after their birth. These disks generally persist for several million years, during which time some material accretes onto the star, some is lost through outflows and photoevaporation, and some condenses into centimeter- and larger-sized bodies or planetesimals. Through observations mainly at IR through millimeter wavelengths, we can determine how common disks are at different ages; measure basic properties including mass, size, structure, and composition; and follow their varied evolutionary pathways. In this way, we see the first steps toward exoplanet formation and learn about the origins of the Solar System. This review addresses observations of the outer parts, beyond 1 AU, of protoplanetary disks with a focus on recent IR and (sub)millimeter results and an eye to the promise of new facilities in the immediate future.

http://www.ifa.hawaii.edu/users/cieza/WC2011_ARAA.pdf

Protoplanetary Disks and Their Evolution

Stellar multiplicity is an ubiquitous outcome of the star formation process Characterizing the frequency and main characteristics of multiple systems and their dependencies on primary mass and environment is therefore a powerful tool to probe this process While early attempts were fraught with selection biases and limited completeness, instrumentation breakthroughs in the last two decades now enable robust analyses In this review, we summarize our current empirical knowledge of stellar multiplicity for Main Sequence stars and brown dwarfs, as well as among populations of Pre-Main Sequence stars and embedded protostars Clear trends as a function of both primary mass and stellar evolutionary stage are identified that will serve as a comparison basis for numerical and analytical models of star formation

Stellar Multiplicity

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations from the 2014 Long Baseline Campaign in dust continuum and spectral line emission from the HL Tau region. The continuum images at wavelengths of 2.9, 1.3, and 0.87 mm have unprecedented angular resolutions of 0.″ 075 (10 AU) to 0.″ 025 (3.5 AU), revealing an astonishing level of detail in the circumstellar disk surrounding the young solar analog HL Tau, with a pattern of bright and dark rings observed at all wavelengths. By fitting ellipses to the most distinct rings, we measure precise values for the disk inclination (46\buildrel{\circ}\over{.} 72+/- 0\buildrel{\circ}\over{.} 05) and position angle (+138\buildrel{\circ}\over{.} 02+/- 0\buildrel{\circ}\over{.} 07). We obtain a high-fidelity image of the 1.0 mm spectral index (α), which ranges from α ∼ 2.0 in the optically thick central peak and two brightest rings, increasing to 2.3–3.0 in the dark rings. The dark rings are not devoid of emission, and we estimate a grain emissivity index of 0.8 for the innermost dark ring and lower for subsequent dark rings, consistent with some degree of grain growth and evolution. Additional clues that the rings arise from planet formation include an increase in their central offsets with radius and the presence of numerous orbital resonances. At a resolution of 35 AU, we resolve the molecular component of the disk in HCO+ (1-0) which exhibits a pattern over LSR velocities from 2–12 km s‑1 consistent with Keplerian motion around a ∼1.3 {M}ȯ star, although complicated by absorption at low blueshifted velocities. We also serendipitously detect and resolve the nearby protostars XZ Tau (A/B) and LkHα358 at 2.9 mm.

https://iopscience.iop.org/article/10.1088/2041-8205/808/1/L3/pdf

The 2014 ALMA Long Baseline Campaign: First Results from High Angular Resolution Observations toward the HL Tau Region

Heat Shock Protein 70 kDa ☆: Molecular Biology, Biochemistry, and Physiology

We present the results of a λ = 2.7 mm continuum interferometric survey of 24 young stellar objects in 11 fields. The target objects range from deeply embedded class 0 sources to optical T Tauri sources. This is the first subarcsecond survey of the λ = 2.7 mm dust continuum emission from young, embedded stellar systems. These multiarray observations, utilizing the high dynamic u-v range of the BIMA array, fully sample spatial scales ranging from 04 to 60'', thus allowing the first consistent comparison of dust emission structures in a variety of systems. The images show a diversity of structure and complexity. The optically visible T Tauri stars (DG Tauri, HL Tauri, GG Tauri, and GM Aurigae) have continuum emission dominated by compact (≤1'') circumstellar disks. In the cases of HL Tauri and DG Tauri, the disks are resolved. The more embedded near-infrared sources (SVS 13 and L1551 IRS 5) have continuum emission that is extended and compact. The embedded sources (L1448 IRS 3, NGC 1333 IRAS 2, NGC 1333 IRAS 4, VLA 1623, and IRAS 16293-2422) have continuum emission dominated by the extended envelope, typically ≥85% of the emission at λ = 2.7 mm. In many of the deeply embedded systems, it is difficult to uniquely isolate the disk emission component from the envelope extending inward to AU-sized scales. Simple estimates of the circumstellar mass in the optical/infrared and embedded systems are in the ranges 0.01-0.08 M☉ and 0.04-2.88 M☉, respectively. All of the target embedded objects are in multiple systems with separations on scales of ~30'' or less. Based on the system separation, we place the objects in three categories: separate envelope (separation ≥6500 AU), common envelope (separation 150-3000 AU), and common disk (separation ≤100 AU). These three groups can be linked with fragmentation events during the star formation process: separate envelopes from prompt initial fragmentation and the separate collapse of a loosely condensed cloud, common envelopes from fragmentation of a moderately centrally condensed spherical system, and common disk from fragmentation of a high angular momentum circumstellar disk.

http://iopscience.iop.org/article/10.1086/308239/pdf

Unveiling the circumstellar envelope and disk: A subarcsecond survey of circumstellar structures

An increase in the synthesis of heat shock proteins that is induced in cells in vitro by hyperthermia or other types of metabolic stress correlates with enhanced cell survival upon further stress. To determine if a similar increase in stress tolerance could be elicited in vivo, rats were made hyperthermic, and then their retinas were tested for sensitivity to light damage. This treatment resulted in a marked decrease in photoreceptor degeneration after exposure to bright light as compared to normothermic animals. Concomitant with such protection was an increase in retinal synthesis of three heat shock proteins. Thus, a physiological rise in body temperature enhances the stress tolerance of nerve tissue, perhaps by increasing heat shock protein production.

https://science.sciencemag.org/content/sci/241/4874/1817.full.pdf

Hyperthermia Protects Against Light Damage in the Rat Retina

All human gamma delta T cells coexpressing the products of the variable (V) region T cell receptor (TCR) gene segments V gamma 9 and V delta 2 recognize antigens from mycobacterial extracts and Daudi cells. Exogenous and endogenous ligands on the cell surface, homologous to the groEL heat shock family, induced reactivities that resembled superantigen responses in this major subset of human peripheral blood gamma delta T cells. Stimulation of human V gamma 9/V delta 2 T cells is not restricted by human leukocyte antigens (HLA), including nonpolymorphic beta 2-microglobulin (beta 2M)-associated class Ib molecules. These data may be important for understanding the role of gamma delta T cells in autoimmunity and in responses to microorganisms and tumors.

http://science.sciencemag.org/content/sci/250/4985/1269.full.pdf

Recognition by human V gamma 9/V delta 2 T cells of a GroEL homolog on Daudi Burkitt's lymphoma cells

Ammonia gas molecules in interstellar medium, discussing detection in direction of galactic center by means of microwave emission

Detection of NH sub 3 molecules in the interstellar medium by their microwave emission.

Water in interstellar regions detected by microwave emission from 6 sub 16 to 5 sub 23 rotational transition

William J. Welch

Papers

Unveiling the circumstellar envelope and disk: A subarcsecond survey of circumstellar structures

Hyperthermia Protects Against Light Damage in the Rat Retina

Recognition by human V gamma 9/V delta 2 T cells of a GroEL homolog on Daudi Burkitt's lymphoma cells

Detection of NH sub 3 molecules in the interstellar medium by their microwave emission.

Detection of Water in Interstellar Regions by its Microwave Radiation