ICE POROSITY IS INTIMATELY LINKED TO THE HISTORY OF FORMATION AND EVOLUTION OF THE ICE. A HIGH POROSITY OF WATER ICE ALLOWS MIXING WITH OTHER MOLECULES, PERMITTING CHEMICAL REACTIONS IN THE ICE BULK AND ON ITS SURFACE. POROSITY ALSO INFLUENCES THE SPECTROSCOPIC INFRARED OBSERVATIONS OF ICES IN SPACE. ONE OF THE MAJOR ACHIEVEMENTS OF THE ESA-ROSETTA MISSION WAS THE PRECISE MEASUREMENT OF THE POROSITY IN THE NUCLEUS OF COMET 67P/CHURYUMOV-GERASIMENKO. IN THE LABORATORY, THE MEASUREMENT OF ICE POROSITY IS USUALLY PERFORMED INDIRECTLY BY MEANS OF SPECTROSCOPY, OBTAINING NON-QUANTITATIVE INFORMATION ON THE POROSITY WHICH IS ALTERED BY THE ROUGHNESS OF THE ICE SURFACE. IN ASTROPHYSICS, IN ADDITION TO WATER, INTERSTELLAR AND SOLAR SYSTEM ICES ARE COMPOSED OF SPECIES SUCH AS CO, CO2, CH3OH, CH4, NH3, ETC. WE PROPOSE THE STUDY AND DEVELOPMENT OF A METHODOLOGY TO ESTIMATE THE POROSITY IN ASTROPHYSICAL ICE ANALOGS. THE SYSTEM IS BASED ON THE EMISSION AND RECEPTION OF AN ULTRASOUND PULSE THROUGH THE ICE LAYER. FOR THAT PURPOSE, IT WOULD BE NECESSARY TO DETERMINE WHICH ULTRASONIC PARAMETERS ARE SENSITIVE TO POROSITY ESTABLISHING A MODEL THAT RELATES THE ULTRASONIC PARAMETERS WITH THE POROSITY. IT WILL BE NECESSARY TO STUDY HOW TO PROPAGATE THE ULTRASONIC WAVES AT TEMPERATURES BELOW 10 K IN A BILAYER STRUCTURE FORMED BY A SUBSTRATE IN WHICH A 10 and 956;M-THICK ICE LAYER IS DEPOSITED. AN ADDITIONAL RISK FOR ULTRASONIC APPLICATIONS IS THAT THE PROCESS OF ICE FORMATION OCCURS IN A ULTRA-HIGH-VACUUM CHAMBER THAT ALLOWS TO CHARACTERIZE AND MONITOR THE ICE DURING ITS FORMATION AND SUBSEQUENT IRRADIATION OR HEATING. SEVERAL EXPERIMENTAL TESTS WILL BE PERFORMED TO VALIDATE THE SYSTEM WITH WATER ICE. SUBSEQUENTLY, THE STUDY OF POROSITY WILL BE EXTENDED TO ICES WHOSE POROSITY HAS BEEN LITTLE STUDIED, IN PARTICULAR SOLID CO. AS A FOLLOW-UP WE PLAN TO MEASURE THE POROSITY OF ICE GROWN UNDER REDUCED GRAVITY IN PARABOLIC FLIGHTS.

NEUTRON STARS ARE A COMPACT ENDPOINT OF THE LIFE OF STARS. THEY LOSE THE BULK OF THEIR ROTATIONAL ENERGY IN THE FORM OF A PULSAR WIND, AN ULTRA-RELATIVISTIC OUTFLOW OF ELECTRONS AND POSITRONS, WHICH PROPERTIES ARE YET ELUSIVE. THIS REQUEST AIMS AT IDENTIFYING WHAT ARE THE CONTROL PARAMETERS BEHIND THE VARIED OBSERVATIONAL PHENOMENOLOGY OF THE PULSED SPECTRA OF NEUTRON STARS, AND TO USE THEM TO PREDICT THEIR X-RAY AND/OR GAMMA-RAY BEHAVIOR SO AS TO GUIDE OBSERVATIONS WITH SATELLITES. THIS PROPOSAL ALSO AIMS AT EXPLORING AND ULTIMATELY OBTAINING A VERSATILE COMBINATION OF HYDRODYNAMICAL, MAGNETO-HYDRODYNAMICAL, AND RADIATIVE SIMULATIONS AND TO APPLY THIS TOOL TO THE MODELLING OF PULSAR WIND NEBULAE. SUCH TOOL, IF VERSATILE ENOUGH TO HANDLE THE FORTHCOMING INCREASE IN THE NUMBER OF DETECTED NEBULAE IN BOTH RADIO AND GAMMA-RAY FREQUENCIES, WILL AT ONCE PROVIDE A FRAMEWORK WHERE TO UNDERSTAND INDIVIDUAL OBSERVATIONS AND ALLOW FOR MEANINGFUL POPULATION ANALYSIS: IT WOULD HAVE AN ENORMOUS IMPACT IN EXTRACTING AND INTERFACING THE PHYSICS OF BOTH THE SQUARE KILOMETER AND THE CHERENKOV TELESCOPE ARRAYS, AT THE TWO ENDS OF THE ELECTROGMAGNETIC SPECTRUM. FOR THE LATTER, IN ADDITION, IT CAN ALSO PLAY A DECISIVE ROLE IN SOLVING FOR THE GAMMA-RAY CONFUSION (THE INABILITY TO SEPARATE THE SOURCES OF RADIATION) GENERATED BY THE DOZENS OF PULSAR WIND NEBULAE TO BE DETECTED IN THE CROWDED GALACTIC CENTER REGION, FOR WHICH WE HERE PROPOSE THE EXPLORATION OF A NEW TECHNIQUE. THIS PROPOSAL HAS A HIGH RISK-HIGH GAIN POTENTIAL: SUCH TOOLS WOULD ALSO HAVE AN IMPACT ON MANY OTHER ASTROPHYSICAL SITUATIONS, IN PARTICULAR, THOSE RELATED WITH PLASMA-MAGNETIC FIELD INTERACTION IN TRANSITIONAL PULSARS AND GAMMA-RAY BINARIES.

THE EMERGENCE OF NEXT-GENERATION SEQUENCING TECHNOLOGIES REPRESENTS A GIANT LEAP TOWARDS THE SYSTEMATIC ANALYSIS OF TRANSCRIPTOMES IN LIVING ORGANISMS. RNA SEQUENCING (RNA-SEQ) HAS BEEN ESTABLISHED AS THE ULTIMATE TOOL TO EXPLORE THE EXPRESSION PROFILE OF CELLS AND TISSUES, PROVIDING A PRECISE, UNBIASED, AND GENOME-WIDE MEASUREMENT OF TRANSCRIPT LEVELS. AN IMPORTANT LIMITATION IN RNA-SEQ STUDIES COMES FROM THE FACT THAT COMPLEX DEVELOPMENTAL AND PHYSIOLOGICAL PROCESSES DEPEND ON THE ACTIVITY OF HETEROGENEOUS CELL POPULATIONS. THIS RESTRICTS CELL-SPECIFIC TRANSCRIPTOMICS TO DISSECTIBLE TISSUES. ALTERNATIVELY, HOMOGENEOUS CELL SUSPENSIONS CAN BE OBTAINED BY CELL SORTING (FACS), BUT THIS METHODOLOGY DEPENDS ON SEVERE CELL DISSOCIATION PROTOCOLS THAT MAY SIGNIFICANTLY ALTER GENE EXPRESSION. THE TRANSLATING RIBOSOME AFFINITY PURIFICATION (TRAP) APPROACH HAS RECENTLY BEEN DEVELOPED AS A POWERFUL TOOL TO OVERCOME THIS LIMITATION. TRAP METHODOLOGY ALLOWS THE CELL-SPECIFIC RECOVERY OF POLYRIBOSOME-ASSOCIATED RNAS BY GENETIC TAGGING OF RIBOSOMES USING CELL AND TISSUE-SPECIFIC PROMOTERS. IN THE PRESENT PROPOSAL WE PLAN TO COMBINE THE TRAP APPROACH WITH ADAPTED ENHANCER TRAP METHODS IN ZEBRAFISH. THE GOAL IS TO CONDUCT A PILOT SCREEN THAT WILL SYSTEMATICALLY GENERATE ZEBRAFISH TRANSGENIC LINES SUITABLE FOR DYNAMIC AND TISSUE-SPECIFIC TRANSCRIPTOMIC INTERROGATION (TRAP-TRAP APPROACH). THE RESULTING COLLECTION OF LINES MAY CONSTITUTE A UNIQUE RESOURCE FOR A BROAD COMMUNITY WORKING IN DEVELOPMENTAL GENETICS, ORGAN PHYSIOLOGY OR DISEASE MODELS. TO MAKE THESE TRANSGENIC LINES, AS WELL AS THE TECHNOLOGY ITSELF, AVAILABLE TO RESEARCHERS OF THE EXPANDING ZEBRAFISH FIELD, WE PLAN TO TRANSFER THE TRAP-TRAP PROTOCOLS TO THE AQUATIC VERTEBRATES PLATFORM, HOSTED IN OUR RESEARCH CENTRE (CABD). THIS CORE FACILITY WILL HAVE THE CAPACITY TO OFFER TECHNOLOGICAL SUPPORT TO USERS INTERESTED IN THE TISSUE-SPECIFIC TRANSCRIPTOMIC ANALYSES PROVIDED BY THE TRAP-TRAP APPROACH.

THE MOLECULAR BASES OF HEPATITIS C VIRUS (HCV) PERSISTENCE ARE LARGELY UNKNOWN. CURRENT MODELS ASSUME THAT THE VIRUS GENETIC MATERIAL REMAINS AS RNA IN THE INFECTED CELL. OUR HYPOTHESIS IS THAT ENDOGENOUS RETROTRANSCRIPTASES ENCODED BY CELLULAR RETROELEMENTS CAN PRODUCE CDNA COPIES OF HCV RNA. WE HAVE HIGH FITNESS HCV POPULATIONS THAT ORIGINATE ELEVATED INTRACELLULAR LEVELS OF HCV RNA THAT SHOULD FAVOR BINDING OF ENDOGENOUS RETROTRANSCRIPTASES AND SYNTHESIS OF HCV CDNA, WITH OR WITHOUT INTEGRATION INTO CELLULAR DNA. WE HAVE ALSO A LARGE COLLECTION OF OLIGONUCLEOTIDE PRIMERS THAT CAN COPY AND AMPLIFY ANY HCV GENOMIC REGION. WE WILL APPLY WALKING TO IDENTIFY THE CELLULAR NUCLEOTIDE SEQUENCE CONTEXT IN WHICH HCV CDNA IS LOCATED. THE PRESENCE OF HCV CDNA COULD EXPLAIN CELLULAR ALTERATIONS THAT FAVOR VIRAL PERSISTENCE, AS WELL AS CELL SEQUELS THAT ARE OBSERVED IN HEPATIC CELLS ONCE THE VIRUS HAS BEEN ELIMINATED BY ANTIVIRAL TREATMENTS. THE PRESENCE OF CDNA WOULD BE A TURNING POINT IN OUR UNDERSTANDING OF PERSISTENT INFECTIONS OF ANIMAL RNA VIRUSES.