MMAB promotes negative feedback control of cholesterol homeostasis

Intricate regulatory networks govern the net balance of cholesterol biosynthesis, uptake and efflux; however, the mechanisms surrounding cholesterol homeostasis remain incompletely understood. Here, we develop an integrative genomic strategy to detect regulators of LDLR activity and identify 250 genes whose knockdown affects LDL-cholesterol uptake and whose expression is modulated by intracellular cholesterol levels in human hepatic cells. From these hits, we focus on MMAB, an enzyme which catalyzes the conversion of vitamin B12 to adenosylcobalamin, and whose expression has previously been linked with altered levels of circulating cholesterol in humans. We demonstrate that hepatic levels of MMAB are modulated by dietary and cellular cholesterol levels through SREBP2, the master transcriptional regulator of cholesterol homeostasis. Knockdown of MMAB decreases intracellular cholesterol levels and augments SREBP2-mediated gene expression and LDL-cholesterol uptake in human and mouse hepatic cell lines. Reductions in total sterol content were attributed to increased intracellular levels of propionic and methylmalonic acid and subsequent inhibition of HMGCR activity and cholesterol biosynthesis. Moreover, mice treated with antisense inhibitors of MMAB display a significant reduction in hepatic HMGCR activity, hepatic sterol content and increased expression of SREBP2-mediated genes. Collectively, these findings reveal an unexpected role for the adenosylcobalamin pathway in regulating LDLR expression and identify MMAB as an additional control point by which cholesterol biosynthesis is regulated by its end product.

Assessment of Plant Sterols in the Diet of Adult Polish Population with the Use of a Newly Developed Database

Plant sterols are compounds with multiple biological functions, mainly cholesterol-reducing. There are no comprehensive databases on plant sterols, which makes it difficult to estimate their intake in the Polish population. This work attempted to use international food databases, additionally supplemented by scientific data from the literature, to create a database of plant sterols, which would cover various kinds of foods and dishes consumed in Poland. The aim was to assess the size and sources of dietary plant sterols in the adult population of Poland. The literature search was conducted using PubMed, Web of Science, Scopus, and Google Scholar to identify possible sources of published food composition data for plant sterols. The study group consisted of 5690 participants of the WOBASZ II survey. We identified 361 dietary sources of plant sterols based on the consumption of foods and dishes reported by participants. Cereals and fats provided 61% of the total plant sterols, and together with vegetables and fruits, this totaled 80%. The median intake of plant sterols in the Polish population was 255.96 mg/day, and for men and women 291.76 and 230.61 mg/day, respectively. Canola oil provided the most plant sterols at 16.92%, followed by white bread at 16.65% and soft margarine at 8.33%. The study found that plant sterol intake in Poland is comparable to other populations, and women’s diets are more dense in plant sterols. Due to the lack of literature sources on plant sterol content in some foods, future studies should expand and complete the databases on plant sterol content in foods.

Desmosterol Incorporation Into Ram Sperm Membrane Before Cryopreservation Improves in vitro and in vivo Fertility

Pregnancy rates in ewes are markedly low after cervical insemination with frozen-thawed sperm. Sensitivity of ram sperm to freeze-thawing is related to the lipid composition of the membrane, particularly to its low sterol content. Recently, we proved that sterol content of ram sperm can be increased by treatment with methyl-β-cyclodextrin-sterol complexes and we provided mechanistic based evidence on the differential behavior of cholesterol and desmosterol in the ram sperm membrane. In the present study, we evaluated the role of increasing cholesterol and desmosterol content of ram sperm before cryopreservation, on the extent and distribution of sterols, cryocapacitation status, acrosome integrity, DNA damage associated with apoptosis and fertility competence in vitro and in vivo of post-thawed sperm. After freeze-thawing, similar levels of sterol content were evidenced in control sperm cells and in those pre-incubated with either cholesterol or desmosterol. Still, moderately higher levels of sterols were registered in treated sperm compared to the control, indicating no physiological excess of sterols after thawing or sterol losses that exceed the control. Live cell imaging of fluorescent cholesterol evidenced the presence of sperm sub-populations differentially affected by freeze-thawing. Similar unimodal frequency profiles were observed between sterol-enriched groups, while the control exhibited a sub-population of sperm compatible with low sterol content. Tyrosine phosphorylation was significantly lower when ram sperm incorporated cholesterol compared to the control. No difference in this capacitation parameter was found between the latter and desmosterol-enriched sperm. The percentage of sperm with damaged acrosomes post-thawing, assessed by a fluorescent lectin, was reduced in sperm that incorporated sterols before freezing, irrespective of the sterol class. These results suggest that sterols exert a stabilizing effect on the acrosome. No differences were found in levels of apoptotic DNA fragmentation among experimental groups. As to fertility trials, desmosterol-enriched sperm gave rise to higher rates of in vitro activated oocytes by heterologous fertilization and to significantly lower pregnancy loss in vivo. Our research provides new insights on sterol incorporation into ram sperm prior to cryopreservation, in particular on the additional benefit of incorporating desmosterol as a strategy to improve fertility outcome.

Effects of nutrient availability and light intensity on the sterol content of Saccharina latissima (Laminariales, Phaeophyceae)

Seaweed phytosterols are associated with potential health benefits, affording them and the seaweeds that produce them commercial interest. However, little is known about how their production is affected by the cultivation environment, limiting the efficiency with which these compounds can be exploited. Therefore, we performed a pilot study on the effect of nutrient availability and light stress on the sterol content of Saccharina latissima, a rapid growing brown alga of increasing interest in western mariculture. Individuals of S. latissima were subjected to a nutrient-replete and nutrient-depleted regime for 5 weeks, followed by the introduction of light-limited and light-saturated conditions in the sixth week; sampling occurred each week. No significant inter-treatment differences were found in the sterol content in week 1–5. However, significant intra-treatment differences were found in weeks 3–5 regardless of nutrient treatment, wherein the fucosterol, 24-methylenecholesterol, and squalene contents of both treatment groups were found to correlate inversely with photosynthetic performance. Factorial treatment of differential nutrient availability and light stress resulted in marked differences between the sterol content of all groups in week 6. Here, squalene and cycloartenol increased in concentration with increasing irradiance regardless of nutrient treatment. Concentrations of all other sterolic components increased with increasing irradiance and low nutrient conditions while decreasing or remaining unchanged with increasing irradiance and high nutrient conditions. Our data shows that within our cultivation conditions and time frame, the sterol content of S. latissima is unaffected by nutrient availability alone but changes with combined alterations in irradiance and nutrient availability. Graphical abstract

Pollen sterols are associated with phylogenetics and environment but not with pollinators

SummaryPhytosterols are primary plant metabolites that have fundamental structural and regulatory functions. They are also essential nutrients for phytophagous insects, including pollinators, that cannot synthesize sterols. Despite the well-described composition and diversity in vegetative plant tissues, few studies have examined phytosterol diversity in pollen.We quantified 25 pollen phytosterols in 122 plant species (105 genera, 51 families) to determine their composition and diversity across plant taxa. We searched literature and databases for plant phylogeny, environmental conditions, and pollinator guilds of the species to examine the relationships with pollen sterols.24-methylenecholesterol, sitosterol and isofucosterol were the most common and abundant pollen sterols. We found phylogenetic clustering of twelve individual sterols, total sterol content and sterol diversity, and of sterol groupings that reflect their underlying biosynthesis pathway (24 carbon alkylation, ring B desaturation). Plants originating in tropical-like climates (higher mean annual temperature, lower temperature seasonality, higher precipitation in wettest quarter) were more likely to record higher pollen sterol content. However, pollen sterol composition and content showed no clear relationship with pollinator guilds.Our study is the first to show that pollen sterol diversity is phylogenetically clustered and that pollen sterol content may adapt to environmental conditions.

ERG11 Polymorphism in Voriconazole-Resistant Candida tropicalis: Weak Role of ERG11 Expression, Ergosterol Content, and Membrane Permeability

ABSTRACTMutations in ERG11 were detected by gene sequencing and amino acid alignment in 18 Candida tropicalis strains with different degrees of sensitivity to voriconazole (VRC). ERG11 expression, sterol content, and membrane permeability were also evaluated. We report three missense mutations in ERG11 that resulted in resistance to VRC. The transcriptional levels of ERG11 as well as the ergosterol content and membrane permeability demonstrated no correlation to only a slight correlation with the obtained MIC values, but the data did suggest a tendency toward such a correlation.

PENGARUH PEMUPUKAN TERHADAP PERTUMBUHAN, PRODUKSI DAN MUTU SIMPLISIA PURWOCENG (Pimpinella pruatjan Molkenb)

ABSTRAK<br />Purwoceng (Pimpinella pruatjan Molkenb.) adalah tanaman obat<br />asli Indonesia yang statusnya langka, dan teknologi budidayanya belum<br />banyak diketahui. Penelitian pengaruh pemupukan terhadap produksi dan<br />mutu simplisia purwoceng telah dilakukan tahun 2004-2005 di Desa<br />Sikunang, Dieng, Jawa Tengah. Perlakuan pemupukannya adalah: (1)<br />kontrol (tidak dipupuk); (2) 9,6 kg pupuk kandang (pk); (3) 96 g urea + 48<br />g SP36 + 72 g KCl; (4) 9,6 kg pk + 96 g urea + 48 g SP36 + 72 g KCl; (5)<br />9,6 kg pk + 96 g urea + 48 g SP36; (6) 9,6 kg pk + 96 g urea + 72 g KCl;<br />(7) 9,6 kg pk + 48 g SP36 + 72 g KCl. Percobaan menggunakan rancangan<br />acak kelompok diulang 4 kali dengan ukuran petak 2,4 m 2 . Hasil penelitian<br />menunjukkan bahwa pemberian pupuk lengkap 9,6 kg pk + 96 g urea + 48<br />g SP36 + 72 g KCl/petak dan pemupukan 96 g urea + 48 g SP36 + 72 g<br />KCl/petak dapat meningkatkan produksi dan mutu simplisia purwoceng.<br />Dibandingkan dengan tanaman yang tidak dipupuk, produksi simplisia<br />meningkat 40%, kadar stigmasterol di akar meningkat 11 – 14 kali. Akar<br />tanaman purwoceng yang tidak dipupuk tidak mengandung sitosterol,<br />tetapi setelah dipupuk mengandung sitosterol sebanyak 16,17 – 17,11 ppm.<br />Tajuk tanaman tidak mengandung bergapten apabila tidak dipupuk, tetapi<br />setelah dipupuk mengandung bergapten 4,92 – 5,56 ppm. Produksi dan<br />mutu simplisia perlakuan 96 g urea + 48 g SP36 + 72 g KCl/petak tidak<br />berbeda nyata dibandingkan dengan perlakuan 9,6 kg pk + 96 g urea + 48<br />g SP36 + 72 g KCl/petak. Ini diduga karena kandungan bahan organik<br />tanah cukup tinggi, sehingga penambahan 96 kg/petak pupuk kandang<br />tidak berpengaruh nyata. Untuk menghasilkan simplisia kering purwoceng<br />secara optimal 8,41 g/tanaman (6,98 kwt/ha) dan bermutu tinggi,<br />diperlukan serapan hara N, P dan K pada jaringan tanaman masing-masing<br />berturut-turut sebanyak 283 mg N; 55 mg P; dan 356 mg K/tanaman atau<br />setara dengan 23,50 kg N; 6,30 kg P; dan 38,90 kg K/ha.<br />Kata kunci: Purwoceng, Pimpinella pruatjan Molkenb, pemupukan,<br />pertumbuhan, produksi, mutu, Jawa Tengah<br />ABSTRACT<br />Effect of fertilizer application on production and quality<br />of Pimpinella pruatjan Molkenb<br />Purwoceng (Pimpinella pruatjan Molkenb) is an Indonesian<br />indigenous medicinal plant. Purwoceng is classified as an endangered<br />species, and its cultivation technology has not been devoleped. The<br />objective of the research was to find out the effect of fertilizer application<br />on the production and quality of purwoceng simplisia. The research was<br />conducted in Sikunang, Dieng, Wonosobo, Central Java from 2004 until<br />2005. The treatments of fertilizer application on 2.4 m 2 were (1) control<br />(without fertilizer); (2) 9.6 kg dung manure (dm); (3) 96 g urea + 48 g<br />SP36 + 72 g KCl; (4) 9.6 kg pk + 96 g urea + 48 g SP36 + 72 g KCl; (5)<br />9.6 kg pk + 96 g urea + 48 g SP36; (6) 96 kg pk + 9.6 g urea + 72 g KCl;<br />(7) 9.6 kg pk + 48 g SP36 + 72 g KCl. The experiment was designed in<br />randomized block designed with four replications. The result of the<br />research showed that the treatments of 9.6 kg dm + 96 g urea + 48 g SP36<br />+ 72 g KCl/2.4 m 2 and 96 g urea + 48 g SP36 + 72 g KCl/2.4 m 2 increased<br />the simplisia production and quality compared with control. The simplisia<br />production increased up to 40% and the stigma sterol content in the roots<br />increased up to 11 – 14 times. The content of sitosterol in the plants with<br />fertilizer application was 6.7 – 17.11 ppm but in the plants without<br />fertilizer application was zero. The content of bergapten in shoot part of<br />plant with fertilizer application was 4.92 – 5.56 ppm, but in the shoot part<br />without fertilizer application was zeros. The production and quality of<br />simplisia with the fertilizer application of 96 g urea + 48 g SP36 + 72 g<br />KCl/2.4 m 2 were not significantly different from those with fertilizer<br />application of 9.6 kg pk + 96 g urea + 48 g SP36 + 72 gKCl/2.4 m 2 . It<br />happened probably because the organic soil content was high, so that the<br />application of 40 ton/ha of dung manure did not give any effect.<br />Furthermore, to increase the optimum production of purwoceng simplisia<br />(6.98 kwt/ha) with high quality it needs 283 mg N, 55 mg P dan 356 mg<br />K/plant or 23.50 kg N, 6.30 kg P, and 38.90 K/ha.<br />Key words : Purwoceng, Pimpinella pruatjan Molkenb, fertilizer<br />application, growth, production, quality, Central Java

2-methyloxolane as alternative solvent for lipid extraction and its effect on the cactus (Opuntia ficus-indica L.) seed oil fractions

The potential of 2-methyloxolane (2-MeO) as an alternative solvent to extract cactus seed oil was compared, in qualitative and quantitative terms, with that of n-hexane, a solvent commonly used for the extraction of edible or cosmetic oils. With 2-MeO, the oil yield was higher (9.55 ± 0.12 g/100 g) than the oil extracted with n-hexane (8.86 ± 0.25 g/100 g). The chemical and physical parameters quality indices (acidity, peroxide value and extinction coefficients (K232 and K270) of 2-methyloxolane extracted oil were found to be much higher than that of oil extracted with n-hexane. A suitable refining scheme will have to be applied, probably leading to slight additional cost and losses. Also, the results showed that the sterol content was higher in the oil obtained with 2-MeO (111.5 ± 2.5 mg/100 g) as a solvent when compared to the oil extracted with n-hexane (102.1 ± 7.54 mg/100 g). However, fatty acid and tocopherol content were not influenced by the extraction solvent. Therefore, the bio-based solvent 2-methyloxolane can be considered as an excellent alternative to the petroleum-based solvent n-hexane for edible/cosmetic oil extraction. The utilization of 2-MeO for oil extraction can drastically reduce the health and environmental impacts associated with n-hexane.