Observation of Danish marine fungi: in memoriam of Dr. Jørgen Koch

Jørgen Koch introduced mycologists to a unique habitat for marine fungi, namely the sand dunes of Grønhøj, Jutland, Denmark. The high diversity of marine fungi obtained from the site provided abundant sporulating structures for a number of research areas in marine mycology including ecological surveys, ultrastructure examination of ascospore appendage development, spore attachment studies and phylogeny. This review highlights the key observations in these areas. Also, a list of 102 species of marine fungi documented for Denmark is provided.

Transcriptome analysis reveals the genetic basis underlying the development of skin appendages and immunity in hedgehog(Atelerix albiventris)

Background: The expression of hair features is an evolutionary adaptation resulting from interactions between many organisms and their environment. Elucidation of the mechanisms that underlie the expression of such traits is a topic in evolutionary biology research; however, the genetic basis of skin appendage development and differentiation remains poorly understood. Therefore, we assessed the de novo transcriptome of the hedgehog ( Atelerix albiventris ) at three developmental stages and compared gene expression profiles between abdomen hair and dorsal spine tissues. Results: We identified 328,576 unigenes in our transcriptome, among which 3,598 were differentially expressed between hair- and spine-type tissues. We identified 3 keratin genes related to hair and spine development through comparative analysis of tissues before and after growth of skin appendages. Dorsal and abdomen skin tissues 5 days after birth were compared and the resulting differentially expressed genes (DEGs) were mainly enriched in keratin filament, intermediate filament, epithelium cell differentiation, and epidermis development based on GO enrichment analysis, and tight junction, p53, and cell cycle signaling pathways based on KEGG enrichment analysis. Expression variations of MBP8, SFN, Wnt10, KRT1 , and KRT2 may be the main factors regulating hair and spine differentiation for the hedgehog. Strikingly, DEGs in hair-type tissues were also significantly enriched in immune-related terms and pathways with hair-type tissues exhibiting more upregulated immune genes than spine-type tissues. Thus, we propose that spine development was an adaptation that provided protection against injuries or stress and reduced hedgehog vulnerability to infection. Conclusion: Our study provided a list of potential genes involved in the regulation of skin appendage development and differentiation in A. albiventris . This is the first transcriptome survey of hair traits for a non-model mammal species, and the candidate genes provided here may provide valuable information for further studies of skin appendages and skin disorder treatments.

Developmental transcriptome and genes related to skin appendage differentiation in hedgehog (Atelerix albiventris)

Background Hedgehog spines are skin appendages that have evolved as a result of the interaction of their skin with the environment. However, such a differentiation mechanism during skin development leads to a high skin appendage diversity, the origins of which are still not fully understood. Spine-skin and hair-skin offer a natural model for the analysis of the genomic basis for the evolution of epidermal appendage formation. We performed a comparative transcriptomic analysis of hedgehog ( Atelerix albiventris ) at multiple developmental stages, and tried to explore the genetic basis for differentiation and development and the resulting expression of the spine-trait. Results A total 15,158 differentially expressed genes (DEGs) were identified. We determined the gene modules and programs corresponding to the various phenotypic traits at different developmental stages by WGCNA analysis. Objective analysis of gene module expression revealed that HIPPO, TGFB, MAPK and Wnt signaling pathways regulate the activation and cell proliferation and differentiation at the skin-appendage development stage. Further, the key genes encoding keratin, FGF, TEAD, and other proteins regulate molecular localization and the cell cycle for hair development and differentiation. Finally, we found a number of highly expressed immune genes in the skin, suggesting that hedgehog spines, unlike pangolin scales, have evolved independently to protect against predators rather than compensate for low autoimmune immunity. Conclusions The variability of gene expression profiles of hair-type and spine-type at multiple development stages, and key candidate genes and pathways at the molecular level might provide evidence that can help elucidate the genetic basis of skin appendage development and differentiation of hedgehog.

Histological and Cytological Characterization of Anther and Appendage Development in Asian Lotus (Nelumbo nucifera Gaertn.)

The lotus (Nelumbo Adans.) is a perennial aquatic plant with important value in horticulture, medicine, food, religion, and culture. It is rich in germplasm and more than 2000 cultivars have been cultivated through hybridization and natural selection. Microsporogenesis and male gametogenesis in the anther are important for hybridization in flowering plants. However, little is known about the cytological events, especially related to the stamen, during the reproduction of the lotus. To better understand the mechanism controlling the male reproductive development of the lotus, we investigated the flower structure of the Asian lotus (N. nucifera). The cytological analysis of anther morphogenesis showed both the common and specialized cytological events as well as the formation of mature pollen grains via meiosis and mitosis during lotus anther development. Intriguingly, an anatomical difference in anther appendage structures was observed between the Asian lotus and the American lotus (N. lutea). To facilitate future study on lotus male reproduction, we categorized pollen development into 11 stages according to the characterized cytological events. This discovery expands our knowledge on the pollen and appendage development of the lotus as well as improving the understanding of the species differentiation of N. nucifera and N. lutea.

Latent developmental potential to form limb-like skeletal structures in zebrafish

The evolution of fins into limbs was a key transition in vertebrate history. A hallmark of this transition is the addition of multiple long bones to the proximal-distal axis of paired appendages. Whereas limb skeletons are often elaborate and diverse, teleost pectoral fins retain a simple endoskeleton. Fins and limbs share many core developmental processes, but how these programs were reshaped to produce limbs from fins during evolution remains enigmatic. Here we identify zebrafish mutants that form supernumerary long bones along the proximal-distal axis of pectoral fins with limb-like patterning. These new skeletal elements are integrated into the fin, as they are connected to the musculature, form joints, and articulate with neighboring bones. This phenotype is caused by activating mutations in previously unrecognized regulators of appendage development, vav2 and waslb, which we show function in a common pathway. We find that this pathway functions in appendage development across vertebrates, and loss of Wasl in developing limbs results in patterning defects identical to those seen in Hoxall knockout mice. Concordantly, formation of supernumerary fin long bones requires the function of hoxall paralogs, indicating developmental homology with the forearm and the existence of a latent functional Hox code patterning the fin endoskeleton. Our findings reveal an inherent limb-like patterning ability in fins that can be activated by simple genetic perturbation, resulting in the elaboration of the endoskeleton.