Pembuatan Alat Peraga Lemari Pendingin Sebagai Media Pembelajaran Mata Kuliah Teknik Pendingin Di Universitas Negeri Semarang

— Media pembelajaran merupakan segala fisik yang menyajikan pesan serta perangsang peserta didik untuk belajar, sehingga keberadaan media pembelajaran penting untuk membantu dalam proses belajar mengajar. Alat peraga adalah salah satu media pembelajaran, dengan memanfaatkan alat peraga proses pembelajaran akan dapat mempermudah dalam memahami materi yang dipelajari oleh mahasiswa, karena ditampilkan dalam bentuk nyata. Teknik Pendingin adalah salah satu mata kuliah yang ada pada Prodi Pendidikan Teknik Elektro. Permasalahannya apakah alat peraga lemari pendingin layak sebagai media pembelajaran pada mata kuliah Teknik Pendingin jurusan Teknik Elektro Universitas Negeri Semarang. Untuk itu perlu diadakan penelitian untuk mengetahui apakah alat peraga lemari pendingin ini layak untuk dignakan sebagai media pembelajaran. Data dikumpulkan dengan metode angket tertutup maupun terbuka. Alat peraga lemari pendingin ini diujicoba oleh dosen ahli materi teknik pendingin. Metode analisis yang digunakan adalah metode analisis statistik deskriptif. Menurut hasil penelitian dari responden secara keseluruhan, alat peraga lemari pendingin pada mata kuliah Teknik Pendingin ini layak digunakan sebagai media pembelajaran. Dosen ahli materi mengemukakan alat peraga ini layak dijadikan alat peraga setelah adanya revisi alat. Berdasarkan dari hasil penelitian dan pembahasan, dapat disimpulkan bahwa menurut mahasiswa media pembelajaran yang berupa alat peraga lemari pendingin pada mata kuliah Teknik Pendingin diwujudkan dengan menyusun prosedur kerja dengan langkah-langkah sebagai berikut: perencanaan alat peraga, penyediaan alat dan bahan, pembuatan alat peraga, validasi alat peraga, uji coba alat peraga, dan evaluasi. Dari hasil penelitian yang telah dilakukan kepada mahasiswa dengan beberapa aspek, alat peraga lemari pendingin ini termasuk dalam kategori layak, sehingga alat peraga ini dapat digunakan sebagai media pembelajaran. Namun masih terdapat kekurangan pada bahan penutup yang dugunakan seharusnya tidak menggunakan kaca agar tidah mudah pecah, dan jika menggunakan kaca suhu yang ada di dalam lemari pendingin masih dapat terpengaruh oleh suhu udara luar. Kata kunci— Media Pembelajaran, teknik pendingin, universitas negeri semarang, alat peraga, lemari pendingi

PcG proteins bind to the potential PREs in human cells.

<p>(<b>A</b>) Assessment of H3K27me3 levels at SLC, A3, and A13 regions using PCR. H3K27me3 ChIP DNA samples from resting T cells and their input controls were analyzed using ³²P-labeled specific primers. Actin was used as control. Band intensities were quantified using Phospho Imager and indicated below the panel. (<b>B, C, D</b>) PcG proteins SUZ12, BMI1, and RING1B are enriched at the SLC and A3 regions compared to the A13 region in resting T cells (<b>B</b>), HeLa cells (<b>C</b>), and SW-13 cells (<b>D</b>), respectively. ChIP assays were performed using antibodies specific for SUZ12, BMI1, and RING1B with chromatin prepared from CD4⁺ T cells, HeLa cells and SW-13 cells. The ChIP DNA was analyzed by qPCR using primers specific for the SLC, A3 and A13 regions (primer sequences in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036365#pone-0036365-t001" target="_blank">Table 1</a>).</p

Normal PcG protein activities are required for the PRE-mediated transcriptional repression.

<p>Knocking down SUZ12 decreased the binding of PRC1 proteins at the endogenous SLC (<b>A</b>) and endogenous A3 (<b>B</b>) regions. ChIP assays were performed using the indicated antibodies, with chromatin from HeLa cells transfected with pREP4-Puro-siSUZ12 or the control vector. ChIP DNA was analyzed by qPCR using primers specific for the SLC-PRE and A3-PRE regions (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0036365#pone-0036365-t001" target="_blank">Table 1</a>). The specificity of ChIP experiment was confirmed by evaluating PcG binding at a region upstream of the <i>BRG1</i> gene locus, which showed very low level of PcG proteins in both the control and SUZ12 knockdown cells. (<b>C</b>) Knocking down SUZ12 in HeLa cells increased the expression of the endogenous <i>SLC17A7</i> (SLC locus) and <i>HoxA3</i> (A3 locus) genes but not the <i>HoxA13</i> (A13 locus) gene. Total RNAs were isolated from HeLa cells transfected with pREP4-Puro-siSUZ12 or a control vector and selected with puromycin. The expression level of the genes was determined by qRT-PCR analysis.</p

Genomic coordinates of the 3 kb human putative PRE regions and sequences of specific primers used in ChIP experiments for each of these regions (sequence information is based on the UCSC hg18 assembly).

<p>Genomic coordinates of the 3 kb human putative PRE regions and sequences of specific primers used in ChIP experiments for each of these regions (sequence information is based on the UCSC hg18 assembly).</p

The putative human PREs repress reporter gene expression in <i>Drosophila</i>.

<p>Quantification of the <i>white</i> gene expression controlled by putative human PREs. mRNA of <i>white</i> was quantified by qRT-PCR and normalized to a constitutively expressed gene <i>rp32L</i> transcript level, followed by multiplying with a factor of 100. For each transgenic line, the qRT-PCR (<i>white/rp32L</i>) data is obtained from 2–3 qPCR reactions and averaged. And for each human DNA element, the data is the average of 5–6 independent lines and the error bars indicate standard error from all independent lines tested.</p

The putative human PREs have characteristics resembling <i>Drosophila</i> PREs in transgenic flies.

<p>(<b>A</b>) Pairing-sensitive silencing of human PREs: The same transgene in heterozygous (upper panels) or homozygous (lower panels) flies. (<b>B</b>) Quantification of results shown in (<b>A</b>) by qRT-PCR analyses. 2–3 PCR reactions were performed for each genotype. (<b>C</b>) Derepression of <i>miniwhite</i> transcription by a mutation in the <i>ph</i> gene. Quantification of <i>white</i> gene transcript from the same <i>miniwhite</i> transgene at either a <i>wild-type</i> background or the <i>ph (ph⁴⁰¹)</i> mutant background by qRT-PCR analyses. 2–3 PCR reactions were performed for each genotype. (<b>D</b>) Repression of <i>miniwhite</i> transcription by a mutation in the <i>trx</i> gene. Quantification of <i>white</i> gene transcript from the same <i>miniwhite</i> transgene in a temperature-sensitive <i>trx (trx¹)</i> background at either the permissive temperature or the restrictive temperature by qRT-PCR analyses. 2–3 PCR reactions were performed for each genotype.</p

Summary of the repression of <i>miniwhite</i> gene expression by human PREs in all the transgenic flies.

<p>Eleven potential human PRE elements were individually tested for their suppression of <i>white</i> gene expression, judged by fly eye color with the corresponding transgene; pair-sensitivity and de-repression by <i>ph⁴⁰¹</i> mutation. The eye color was classified to eight levels from −4 to +4, where −4 was the palest and +4 the darkest. On average 5–6 independent lines were tested for each transgene and the results were summarized. The strongest group contains SLC, NPR, LGR and NeuD; the intermediate group is consisted of A3, XKR, PITX and BCAN; and the weakest group includes PDE, UNC and A13. BRG serves as a control.</p

The putative human PRE SLC element has enriched <i>Drosophila</i> PcG protein binding in transgenic flies.

<p>The H3K27me3 modification and <i>Drosophila</i> PcG proteins are enriched at the SLC region compared to the A13 region. The H3K27me3 modification is also enriched at the A3 region compared to the A13 region, but no enrichment of <i>Drosophila</i> PcG proteins has been detected at the A3 region. ChIP assays were performed using antibodies specific for H3K27me3, E(z), and Pc with chromatin prepared from fly heads. The ChIPed DNA was analyzed by qPCR using primers specific for either the SLC or the A3 region and normalized to the A13 region in the same ChIP experiment. 2–3 independent ChIP experiments were performed for each antibody and three qPCR reactions were performed for each region in every ChIP experiment.</p

Gene functional analysis of the genes with unique histone modification islands in different groups.

<p>A. Gene functional analysis of the genes with unique H3K4me3 islands by IPA. Except for Line 6₃ non-infected group, 10 enriched pathways were shown in figure. Larger size of the sector means this pathway is represented by more genes. 63.Non: Line 6₃ non-infected group; 63.Inf: Line 6₃ infected group; 72.Non: Line 7₂ non-infected group; 72.Inf: Line 7₂ infected group. B. Gene functional analysis of the genes with unique H3K27me3 islands.</p

Percentage of genes with only H3K4me3, or only H3K27me3 or both H3K4me3 and H3K27me3 enrichment in the chicken genome for each group.

<p>When there is an overlap of the H3K4me3 island with the TSS of a gene, it was defined as the H3K4me3 enrichment on this gene. For H3K27me3, the enrichment was defined as the overlap with the gene body of a gene.</p