Ribosomally derived lipopeptides containing distinct fatty acyl moieties

Lipopeptides represent a large group of microbial natural products that include important antibacterial and antifungal drugs and some of the most-powerful known biosurfactants. The vast majority of lipopeptides comprise cyclic peptide backbones N-terminally equipped with various fatty acyl moieties. The known compounds of this type are biosynthesized by nonribosomal peptide synthetases, giant enzyme complexes that assemble their products in a non–gene-encoded manner. Here, we report the genome-guided discovery of ribosomally derived, fatty-acylated lipopeptides, termed selidamides. Heterologous reconstitution of three pathways, two from cyanobacteria and one from an arctic, ocean-derived alphaproteobacterium, allowed structural characterization of the probable natural products and suggest that selidamides are widespread over various bacterial phyla. The identified representatives feature cyclic peptide moieties and fatty acyl units attached to (hydroxy)ornithine or lysine side chains by maturases of the GCN5-related N-acetyltransferase superfamily. In contrast to nonribosomal lipopeptides that are usually produced as congener mixtures, the three selidamides are selectively fatty acylated with C10, C12, or C16 fatty acids, respectively. These results highlight the ability of ribosomal pathways to emulate products with diverse, nonribosomal-like features and add to the biocatalytic toolbox for peptide drug improvement and targeted discovery.

VALIDITAS PERANGKAT PEMBELAJARAN MATEMATIKA DENGAN METODE PENEMUAN TERBIMBING PADA MATERI LINGKARAN KELAS VIII SMP

The purpose of this research is to produce a mathematics learning tool in the form of the lesson plan and student's worksheet using the guided discovery method on the circle material of class VIII junior high school which has been tested valid. This development refers to the Research and Development (R&D) model which includes 10 stages, namely potential and problems, data collection, product design, design validation, design revisions, product trials, design revisions, usage trials, product revisions, and mass production. Modified according to the needs of this research into 6 stages, namely potential and problems, data collection, product design, design validation, design revision, and final product. The data analysis technique used is the descriptive analysis technique. The validation sheet was used as a data collection instrument in this research. The validation sheet is filled out by 3 validators consisting of 2 lecturers of the mathematics education study program FKIP UIR and 1 mathematics teacher. Based on the results of the lesson plan validation, a percentage of 85.6% was obtained with very valid criteria, while the students’ worksheet validation results were 82.6% with fairly valid criteria. This research concludes that mathematics learning tools have been obtained using the guided discovery method in class VII junior high school on the circle material which has been tested valid.

Pengaruh Model Penemuan Terbimbing Berbantuan WEB Terhadap Keterampilan Berpikir Kritis Matematis Siswa Kelas X

The background of this research is, there is no learning model that can optimally support critical thinking skills, so it takes an innovative learning model. In this case, the researchers used web helped to guide discovery learning model to improve the critical thinking skills of the student in class X SMAN 4 Praya in academic year 2019/2020. This study aimed to find an effect of web assisted guided discovery learning on trigonometry material to critical thinking ability of the student in class X SMAN 4 Praya in academic year 2019/2020. This study use a quantitative research approach to the type of experimental research. In this experiment the researchers used a quasi-experimental, and uses two classes as a research, the experimental class and control class. The population of this research is all the student in class X SMAN 4 Praya and and choose two class as a sample class that is X MIPA 5 as a experimental class and X MIPA 3 as control class. Student in experimental class used web assisted guided discovery learning model and in control class used guided discovery without web assisted. The result of the research showed that the average of critical thinking ability in the experimental class is better than control class which is in the experimental class is in the less effective category and control class in ineffective category.

Developing Guided Discovery Learning-Based Neurodroid Learning Media for Critical Thinking Skills

This study aimed to develop guided discovery learning-based android learning media to improve critical thinking skills. The developed biology learning media was applied to the nervous system material. The discussion of the physiology of the nervous system is one of the difficult biological materials to understand because it includes the organization and structure of neurons and their functions, ion pump mechanisms when neurons are at rest, action potential mechanisms, mechanisms for neurons to communicate with other cells in the synapses, and organization of the nervous system. This study used research and development (RD) with a method developed by Thiagarajan, namely the 4D model with stages: define, design, develop and disseminate. The stages of this study are limited to the development stage. The results showed that the media was feasible with media, language, and a material expert validation of 3.5, 3.8, and 3.3, respectively.

Profile of Guided Discovery Learning Implementation Assisted by Virtual Lab and Students’ Problem-Solving Skills on Gas Kinetic Theory

This research was conducted to obtain a guided discovery learning implementation profile with virtual lab assistance and problem-solving skills for high school students on gas kinetic theory. The type of research was descriptive preliminary research, without hypothesis testing. The research subjects consisted of 106 students in senior high school. This study used qualitative descriptive analysis from questionnaires and online tests. This study revealed that the level of students’ problem-solving skills was low. This case was proven by 102 students (27 male; 75 female) in the low category with a score range of 0 to 45, and four students in the moderate category with a score range of 46 to 75, while there were no students in the high category with a score range of 76 to 100. This research implies that there is a need for a guided discovery learning model with the help of a virtual lab to analyze the problem-solving skills of high school students, especially on gas kinetic theory.

IMPLEMENTASI MODEL GUIDED DISCOVERY LEARNING BERBANTUAN AUDIO VISUAL UNTUK MENINGKATKAN MINAT BELAJAR DAN PEMAHAMAN KONSEP SISWA PADA MATERI ELASTISITAS DAN HUKUM HOOKE

Penelitian ini bertujuan untuk mengetahui peningkatan minat belajar dan pemahaman konsep siswa pada materi elastisitas dan hukum Hooke yang diajarkan melalui model GDL berbantuan media audio-visual di MAN 4 Aceh Besar. Metode dalam penelitian ini adalah quasi eksperimen dengan desain pretest posttest control group. Penelitian ini dilakukan pada siswa kelas XI MAN 4 Aceh Besar. Teknik pengambilan sampel dalam penelitian ini adalah purposive sampling. Instrumen yang digunakan adalah angket dan soal. Hasil analisis uji t (independent sample t test) diperoleh nilai signifikansi 0,000 < 0,05, sehingga dapat disimpulkan bahwa Ha diterima artinya terdapat perbedaan rata-rata minat belajar siswa kelas eksperimen dan kelas kontrol. Hasil analisis N-gain kelas eskperimen diperoleh skor rata-rata 0,68 dan kelas kontrol diperoleh skor rata-rata 0,42 kategori sedang. Hasil analisis uji t (independent sample t test) diperoleh nilai signifikansi 0,000 < 0,05, sehingga dapat disimpulkan bahwa Ha diterima artinya terdapat perbedaan rata-rata pemahaman konsep siswa kelas eksperimen dan kelas kontrol. Kesimpulan dalam penelitian ini membuktikan bahwa GDL berbantuan media audio-visual dapat meningkatkan minat belajar siswa dan pemahaman konsep siswa pada materi elastisitas dan hukum Hooke. Keywords: Model Guided Discovery Learning (GDL), Minat Belajar dan Pemahaman Konsep Siswa

Genome-Guided Discovery of the First Myxobacterial Biarylitide Myxarylin Reveals Distinct C–N Biaryl Crosslinking in RiPP Biosynthesis

Ribosomally synthesized and post-translationally modified peptides (RiPPs) are a structurally diverse group of natural products. They feature a wide range of intriguing post-translational modifications, as exemplified by the biarylitides. These are a family of cyclic tripeptides found in Planomonospora, carrying a biaryl linkage between two aromatic amino acids. Recent genomic analyses revealed that the minimal biosynthetic prerequisite of biarylitide biosynthesis consists of only one ribosomally synthesized pentapeptide precursor as the substrate and a modifying cytochrome-P450-dependent enzyme. In silico analyses revealed that minimal biarylitide RiPP clusters are widespread among natural product producers across phylogenetic borders, including myxobacteria. We report here the genome-guided discovery of the first myxobacterial biarylitide MeYLH, termed Myxarylin, from Pyxidicoccus fallax An d48. Myxarylin was found to be an N-methylated tripeptide that surprisingly exhibits a C–N biaryl crosslink. In contrast to Myxarylin, previously isolated biarylitides are N-acetylated tripeptides that feature a C–C biaryl crosslink. Furthermore, the formation of Myxarylin was confirmed by the heterologous expression of the identified biosynthetic genes in Myxococcus xanthus DK1622. These findings expand the structural and biosynthetic scope of biarylitide-type RiPPs and emphasize the distinct biochemistry found in the myxobacterial realm.