Mars Extant Life: What's Next? Conference Report.

On November 5-8, 2019, the "Mars Extant Life: What's Next?" conference was convened in Carlsbad, New Mexico. The conference gathered a community of actively publishing experts in disciplines related to habitability and astrobiology. Primary conclusions are as follows: A significant subset of conference attendees concluded that there is a realistic possibility that Mars hosts indigenous microbial life. A powerful theme that permeated the conference is that the key to the search for martian extant life lies in identifying and exploring refugia ("oases"), where conditions are either permanently or episodically significantly more hospitable than average. Based on our existing knowledge of Mars, conference participants highlighted four potential martian refugium (not listed in priority order): Caves, Deep Subsurface, Ices, and Salts. The conference group did not attempt to reach a consensus prioritization of these candidate environments, but instead felt that a defensible prioritization would require a future competitive process. Within the context of these candidate environments, we identified a variety of geological search strategies that could narrow the search space. Additionally, we summarized a number of measurement techniques that could be used to detect evidence of extant life (if present). Again, it was not within the scope of the conference to prioritize these measurement techniques-that is best left for the competitive process. We specifically note that the number and sensitivity of detection methods that could be implemented if samples were returned to Earth greatly exceed the methodologies that could be used at Mars. Finally, important lessons to guide extant life search processes can be derived both from experiments carried out in terrestrial laboratories and analog field sites and from theoretical modeling.

IPV--bridging the juridical gap between scratches and DNA detection under fingernails of cohabitating partners.

Intimate partner violence (IPV) is a global health issue with lifetime prevalences of physical and sexual violence against women of 12-71% in various populations. Due to its clandestine nature third party eye witnesses are scarce and prosecution of these cases has to rely on medical examination results, e.g. injury patterns of the victim and the perpetrator. Medicolegal assessment of DNA of the male partner found in fingernail specimen of the female partner after an assault is difficult since cohabitating couples are known to carry DNA of the respective partner in 17% of examined couples. In this study, male and total DNA content in fingernail specimen of 34 couples was analyzed after vigorous scratching of the male partners flank. Scratching and non-scratching fingers showed a highly significant difference in absolute and relative male DNA content allowing for the differentiation of DNA transfer caused by normal cohabitation and scratching during an assault.

[The effectiveness of limbus epithelium transplantation]. / Untersuchung zur Effektivität der Limbusepitheltransplantation.

BACKGROUND: The transplantation of the limbus is based on the theory that limbal stem cells are necessary for epithelialisation and maintenance of a clear cornea. We used a genetic analysis procedure to demonstrate the survival of transplanted limbus stem cells. PATIENT AND METHODS: A lamellary corneal graft and limbus transplantation from donor material was carried out on a patient with severe alkali burns and destroyed Bowmann's membrane to prepare the cornea for perforating keratoplasty. Subsequently, perforating corneal graft was carried out and the epithelium and endothelium of the removed cornea were analysed with a gene analytical procedure. For the cellular typing we used the SGM kit, well known in forensic analysis, that allows simultaneous detection of alleles at 11 loci. The genetic analysis was performed using an ABI PRISM 310 Genetic Analyser (Perkin Elmer Applied Biosystems) after DNA amplification by the polymerase chain reaction. RESULTS: The cornea-limbus transplant was integrated without vascularisation from the limbus under treatment with cyclosporin A. The epithelium cells of the corneal tissue gained by keratoplasty had the same genetic pattern as the primary donor in all loci, but no congruence with the recipient (except for the amelogenin marker because both the donor and the recipient were males). Therefore the epithelium cells must have originated from the transplanted stem cells of the donor. CONCLUSIONS: The identical genetic pattern found for the donor and the epithelium of the corneal-limbal transplant demonstrate the survival of the transplanted stem cells in a patient with adequate cytostatic therapy.

Assessing the plausibility of life on other worlds.

As the field of astrobiology matures and search strategies for life on other worlds are developed, the need to analyze in a systematic way the plausibility for life on other planetary systems becomes increasingly apparent. We propose the adoption of a simple plausibility of life (POL) rating system based on specific criteria. Category I applies to any body shown to have conditions essentially equivalent to those on Earth. Category II applies to bodies for which there is evidence of liquid water and sources of energy and where organic compounds have been detected or can reasonably be inferred (Mars, Europa). Category III applies to worlds where conditions are physically extreme but possibly capable of supporting exotic forms of life unknown on Earth (Titan, Triton). Category IV applies to bodies that could have seen the origin of life prior to the development of conditions so harsh as to make its perseverance at present unlikely but conceivable in isolated habitats (Venus, Io). Category V would be reserved for sites where conditions are so unfavorable for life by any reasonable definition that its origin or persistence there cannot be rated a realistic probability (the Sun, gas giant planets). The proposed system is intended to be generic. It assumes that life is based on polymeric chemistry occurring in a liquid medium with uptake and degradation of energy from the environment. Without any additional specific assumptions about the nature of life, the POL system is universally applicable.

Application of DNA filter hybridization and PCR to distinguish between human and non-human tissues of poor quality.

The present report describes a novel approach for the identification of human or non-human specimens after long-term storage in a badly preserved state. The application of the PCR-technique (polymerase chain reaction) using human-specific primers as well as Southern blot (filter) hybridization of the sample DNA to a primate-specific DNA probe enabled us to extend the positive identification beyond the limits of conventional methods such as serological or morphological examinations.

Concentration of tumour markers CEA, AFP, alpha and beta subunits of hCG in cerebrospinal fluid in children with inflammatory diseases of the central nervous system.

Carcinoembryonic antigen (CEA), alphafetoprotein (AFP) and alpha-beta subunits of human chorionic gonadotropin (hCG) were determined by radio-immunoassay in CSF of 83 children presenting some central nervous disease and compared to the corresponding values obtained in 88 children without neuroinfection. CEA and alpha hCG were absent in the CSF of children without neuroinfection. CEA and alpha hCG levels in CSF higher than 0.0 ng/ml were regarded as elevated. In patients with inflammatory process of CNS, CEA values were positive in 9% (maximum 8.0 ng/ml) and alpha hCG in 4% (maximum 5.0 ng/ml). AFP in CSF ranged from 15.0 to 49.0 ng/ml in children without neuroinfection, and from 0.0 to 100.0 ng/ml in patients with inflammatory diseases of the CNS. As a normal upper limit of AFP in CSF, 53.2 ng/ml is suggested; in 31% of the patients with inflammatory diseases of CNS the AFP level was elevated. The normal upper limit of beta hCG concentration in CSF was regarded as 0.4 ng/ml; in 12% of the patients with viral meningoencephalitis the beta hCG level in CSF was slightly elevated, it ranged from 0.5 to 3.0 ng/ml.