Functional consequence of variation in melanoma antigen expression

Summary Melanoma cells have been shown to express melanoma-associated antigens and, in many cases, the histocompatibility antigen, HLA-DR. We questioned whether the expression of these antigens was quantitatively altered during the serial passage of melanoma cells in culture. Therefore, we measured the binding of monoclonal antibodies specific for a melanoma-specific antigen and the HLA-DR antigen to melanoma cells from serial passages. Three cell lines were studied. We found that although both the melanoma-associated antigen and the HLA-DR antigen were qualitatively conserved, significant quantitative differences were seen. To study the functional consequences of these differences, we used fluorescence-activated cell sorting to create DR-enriched and DR-depleted populations from a single melanoma cell line heterogeneous for DR expression. We found that the proliferation of allogeneic T cells (measured by the ³H-TdR uptake) cultured with the DR-enriched and -depleted melanoma cell populations was directly related to the amount of the HLA-DR antigen expressed. These results indicate that in performance of experiments using melanoma cell lines quantitative assessment of antigenic expression is important, particularly if the function of a specific antigen is under examination. Further, our data clearly identify the HLA-DR antigen on melanoma cells as a participant in allogeneic lymphocyte stimulation. Abbreviations used are: FACS, fluorescence activated cell sorter; FITC, fluorescein isothocyante; ³H-TdR, tritiated thymidine     

Larval Connectivity and the International Management of Fisheries

Predicting the oceanic dispersal of planktonic larvae that connect scattered marine animal populations is difficult, yet crucial for management of species whose movements transcend international boundaries. Using multi-scale biophysical modeling techniques coupled with empirical estimates of larval behavior and gamete production, we predict and empirically verify spatio-temporal patterns of larval supply and describe the Caribbean-wide pattern of larval connectivity for the Caribbean spiny lobster (Panulirus argus), an iconic coral reef species whose commercial value approaches $1 billion USD annually. Our results provide long sought information needed for international cooperation in the management of marine resources by identifying lobster larval connectivity and dispersal pathways throughout the Caribbean. Moreover, we outline how large-scale fishery management could explicitly recognize metapopulation structure by considering larval transport dynamics and pelagic larval sanctuaries.     

Guanylate-binding Protein 1 (Gbp1) Contributes to Cell-autonomous Immunity against Toxoplasma gondii

IFN-γ activates cells to restrict intracellular pathogens by upregulating cellular effectors including the p65 family of guanylate-binding proteins (GBPs). Here we test the role of Gbp1 in the IFN-γ-dependent control of T. gondii in the mouse model. Virulent strains of T. gondii avoided recruitment of Gbp1 to the parasitophorous vacuole in a strain-dependent manner that was mediated by the parasite virulence factors ROP18, an active serine/threonine kinase, and the pseudokinase ROP5. Increased recruitment of Gbp1 to Δrop18 or Δrop5 parasites was associated with clearance in IFN-γ-activated macrophages in vitro, a process dependent on the autophagy protein Atg5. The increased susceptibility of Δrop18 mutants in IFN-γ-activated macrophages was reverted in Gbp1^−/− cells, and decreased virulence of this mutant was compensated in Gbp1^−/− mice, which were also more susceptible to challenge with type II strain parasites of intermediate virulence. These findings demonstrate that Gbp1 plays an important role in the IFN-γ-dependent, cell-autonomous control of toxoplasmosis and predict a broader role for this protein in host defense.     

DEVELOPMENT OF A LEXICON FOR BEEF FLAVOR IN INTACT MUSCLE

ABSTRACT

A lexicon describing the flavor characteristics of beef across different cuts, grades, and cooking temperatures and methods was developed. Four major cuts of the United States Department of Agriculture (USDA) quality grade beef were cooked to five endpoint temperatures using braising, broiling (oven broiling and electric charbroiling), roasting and grilling (indoor and outdoor grilling). Six highly trained panelists identified and defined a total of 38 aroma and flavor characteristics in 176 beef samples. Beef identity, brown/roasted, bloody/serumy, metallic, fat‐like, overall sweet, sour aromatics and five tastes were present in practically all samples. Other attributes were present only in certain samples, depending on either the sample group or the cooking method/endpoint temperature combination used. This lexicon potentially offers the beef industry a standard tool to identify and quantify flavor attributes as impacted by temperature, cooking method, aging process, storage time, diet regime, packaging, USDA quality grades, etc.

PRACTICAL APPLICATIONS

Until now, the beef industry's main focus has been to assess beef tenderness and juiciness, with an emphasis on ways to improve beef texture. Meat companies and academic institutions have been using the 1995 American Meat Science Association guidelines to assess the flavor of beef, which are not comprehensive. Recent work has focused on flavor, and the industry needs a standardized flavor lexicon that can be used for many projects. It is important for the industry to be able to systematically identify and quantify flavor attributes that drive consumer acceptance.     

PISCIVORY IN THE FEATHERED DINOSAUR MICRORAPTOR

The largest specimen of the four‐winged dromaeosaurid dinosaur Microraptor gui includes preserved gut contents. Previous reports of gut contents and considerations of functional morphology have indicated that Microraptor hunted in an arboreal environment. The new specimen demonstrates that this was not strictly the case, and offers unique insights into the ecology of nonavian dinosaurs early in the evolution of flight. The preserved gut contents are composed of teleost fish remains. Several morphological adaptations of Microraptor are identified as consistent with a partially piscivorous diet, including dentition with reduced serrations and forward projecting teeth on the anterior of the dentary. The feeding habits of Microraptor can now be understood better than that of any other carnivorous nonavian dinosaur, and Microraptor appears to have been an opportunistic and generalist feeder, able to exploit the most common prey in both the arboreal and aquatic microhabitats of the Early Cretaceous Jehol ecosystem.     

Genomic Background and Generation Time Influence Deleterious Mutation Rates in Daphnia

Understanding how genetic variation is generated and how selection shapes mutation rates over evolutionary time requires knowledge of the factors influencing mutation and its effects on quantitative traits. We explore the impact of two factors, genomic background and generation time, on deleterious mutation in Daphnia pulicaria, a cyclically parthenogenic aquatic microcrustacean, using parallel mutation-accumulation experiments. The deleterious mutational properties of life-history characters for individuals from two different populations, and for individuals maintained at two different generation times, were quantified and compared. Mutational properties varied between populations, especially for clutch size, suggesting that genomic background influences mutational properties for some characters. Generation time was found to have a greater effect on mutational properties, with higher per-generation deleterious mutation rates in lines with longer generation times. These results suggest that differences in genetic architecture among populations and species may be explained in part by demographic features that significantly influence generation time and therefore the rate of mutation.     

Effects of Clomipramine Administration on Syrian Hamster Circadian System and Behavior

The aim of the present work is to discuss the available data on neonatal and adult antidepressant treatment in relation to animal models of depression and serotonergic modulation of the circadian system, with a particular emphasis on our own published and unpublished work on the effects of clomipramine (a serotonin reuptake inhibitor) on the Syrian hamster circadian behavior. Neonatal clomipramine treatment (15 mg/kg from postnatal days 8 to 21) significantly augmented the amplitude of the wheel running rhythm, as well as delayed its acrophase and increased the time to reentrain after a 6-h phase advance of the light-dark cycle. Neonatally clomipramine-treated hamsters had a shorter circadian period than saline-treated animals under constant light - but not under constant dark- conditions, exhibited decreased phase advances after light pulses applied at late subjective night and greater phase advances after i.p. administration of the 5-HT_1A-receptor agonist 8-OH-DPA at midday. These animals also exhibited more locomotor activity than controls, but did not display the typical circadian variation in anxiety-related behavior, as measured in a plus-maze paradigm. They also showed an increased 5-HIAA/5-HT ratio in hypothalamus and midbrain raphe, while 5-HT content was decreased in frontal cortex and anterior hypothalamic areas. Since drugs linked to the serotonergic system are able to modify the circadian system, we decided to test whether acute and chronic clomipramine administration in adulthood was able to change: a) the phase of free running activity rhythms; (b) light-induced phase shifts, and (c) hypothalamic 5-HT turnover. Acute clomipramine injection had a phase-dependent effect on the free running activity rhythm, with phase advances at CT 0-8 being significantly higher than at CT 8-16. Pretreatment with clomipramine inhibited phase advances in response to light pulses when applied at CT 19 while phase delays at CT 14 remained unaffected. This acute treatment also decreased 5-HT turnover in the SCN at both CTs. In contrast, chronic clomipramine administration potentiated light-induced phase advances, without changes in period, amplitude or central 5-HT turnover. Taken together, these data support the view that clomipramine, as other antidepressant drugs, can affect the expression of the circadian rhythmicity in Syrian hamsters, possibly through serotonergic mechanisms in the case of acute treatments, and more complex behavioral interaction in the case of neonatal and chronic treatments.