Lichens are a symbiotic form of life formed by filamentous fungi and 1 or 2 autotrophic microorganisms. Its diversity depends on the natural area conservation and pollutants presence, and they represent an ecological niche with novel secondary metabolic compounds. This work is a preliminary study of the diversity of crustose lichens in Guanajuato State, Mexico. A collection of 48 lichen samples was carried out in different places such as Cerro del Piloncillo, Cerro del Veinte, Cerro Panales, Sierra of Pénjamo, and Sierra de Lobos. Classic lichen identification tests and description, chemical reactions, and microcrystallization were carried out. Representative genera were identified, such as Xanthoria spp., Lecanora spp., Candelariella spp., and Diploschistes spp., also 21 chemical compounds were identified by microcrystallization such as gyrophoric acid and divaritic acid. The Sierra de Santa Rosa has the greatest diversity of lichens. The distribution of the diversity of crustose lichens in Guanajuato State is an indicator of the conservation of a place and the low impact of contaminants, it also contributes to the formation of the biodiversity catalog and promotes the exploration of chemical compounds, and microbiological studies in lichens. This exploratory study highlights the presence of four species widely distributed, and the distribution of crustose lichens in urban places and natural areas, which is a characteristic that can be used as an indicator of the conservation of ecosystems, the impact of pollution, and their identification, as well as a conservation and restoration studies of contaminated places.

During routine laboratory work in molecular biology, gel electrophoresis is used to follow experiments related to DNA, such as PCR, DNA extraction, and DNA digestion, and the use of molecular markers as important components for subsequent analysis is crucial, considering the quality of the DNA, the putative concentration, which is a qualitative measure of the molecular marker used as a reference, and the size of the DNA sample. There are nice and diverse molecular markers for use according to our needs; however, they could be expensive and inadequate for routine DNA analysis. In this work, we describe the preparation of a DNA molecular marker via a classical method. In essence, we digest Lambda phage DNA through two different restriction reactions, the StyI and HindIII enzymes, which produce the classical and popular DNA molecular marker used before the actual DNA Ladder molecular marker. We mix both digestion methods and produce a good and useful DNA molecular marker called Lambda HS. Both digestions produced 17 bands, from 23103 to 421 pb. The cost of production is also affordable for a typical molecular biology lab.