Change in apparent and true absorption and retention of dietary zinc with age in rats

Two groups of 16 rats each were fed the same diet with 12.9 ppm Zn. Nine days after each animal was injected with⁶⁵Zn for assessing fecal zinc of endogenous origin, zinc intake and excretion were determined for a six-day period at the age of about five (group I) and nine (II) weeks. At mean growth rates of 5.1 and 5.2 g/day, food consumption per gram of gain was 2.01 g in group I vs 2.86 g in II. Overall, zinc retention amounted to 21 vs 25 μg Zn/g of gain. Apparent absorption averaged 92 vs 74% of Zn intake (132 vs 189 μg/day), while true absorption averaged 98 vs 92%. It was concluded that endogenous fecal zinc excretion was limited to the indispensable loss (F _em) in group I (7 μg/day), while it exceeded this minimum loss in group II (33 μg/day). True retention, which reflected total zinc utilization (true absorption times metabolic efficiency), was derived from apparent absorption plusF _em (11 μg/day for group II according to the greater metabolic body size of the rats). It averaged 98% of Zn intake in group I vs 80% in group II. The mean metabolic efficiency was 100% vs 87%. The conclusion was that these marked differences between age groups in utilizing the dietary zinc reflected the efficient homeostatic adjustments in absorption and endogenous excretion of zinc to the respective zinc supply status.     

Development of a high-throughput screening assay for cytoprotective agents in rotenone-induced cell death

Parkinson’s disease (PD) is a neurodegenerative disease featured by selective loss of substantia nigra neurons. Rotenone administration in animals induces neurodegeneration accompanied by α-synuclein-positive Lewy body-like inclusions, recapturing typical histopathological features of PD. In an effort to screen for small-molecule agents to reverse rotenone-induced cytotoxicity, we developed and validated a sensitive and robust assay with neuroblastoma SK-N-SH cells. This assay was amenable to a high-throughput screening format with Z′ factor of 0.56. Robotic screening of a bioactive compound library led to the identification of carnosic acid that can effectively protect cells from rotenone treatment. Using a high-content image-based assay and Western blot analysis, we demonstrated that carnosic acid protects cells from rotenone stress by significant induction of HSP70 expression. Therefore, the assay reported here can be used to identify novel cytoprotective agents for clinical therapeutics of PD.     

Testing prediction accuracy in short-term ecological studies

Applied ecology is based on an assumption that a management action will result in a predicted outcome. Testing the prediction accuracy of ecological models is the most powerful way of evaluating the knowledge implicit in this cause-effect relationship, however, the prevalence of predictive modeling and prediction testing are spreading slowly in ecology. The challenge of prediction testing is particularly acute for small-scale studies, because withholding data for prediction testing (e.g., via k-fold cross validation) can reduce model precision. However, by necessity small-scale studies are common. We use one such study that explored small mammal abundance along an elevational gradient to test prediction accuracy of models with varying degrees of information content. For each of three small mammal species, we conducted 5000 iterations of the following process: (1) randomly selected 75 % of the data to develop generalized linear models of species abundance that used detailed site measurements as covariates, (2) used an information theoretic approach to compare the top model with detailed covariates to habitat type-only and null models constructed with the same data, (3) tested those models’ ability to predict the 25 % of the randomly withheld data, and (4) evaluated prediction accuracy with a quadratic loss function. Detailed models fit the model-evaluation data best but had greater expected prediction error when predicting out-of-sample data relative to the habitat type models. Relationships between species and detailed site variables may be evident only within the framework of explicitly hierarchical analyses. We show that even with a small but relatively typical dataset (n = 28 sampling locations across 125 km over two years), researchers can effectively compare models with different information content and measure models’ predictive power, thus evaluating their own ecological understanding and defining the limits of their inferences. Identifying the appropriate scope of inference through prediction testing is ecologically valuable and is attainable even with small datasets.     

Analysis of the developmental expression of small VCP-interacting protein and its interaction with steroidogenic acute regulatory protein in Leydig cells

Small VCP-interacting protein (SVIP) is a 9-kDa protein that is composed of 76 amino acids, and it plays a role in the endoplasmic reticulum-associated protein degradation (ERAD) pathway. Recent studies have shown that SVIP is an androgen-responsive protein and its expression is regulated by androgens. Because no data are available regarding the cellular localization and expression of SVIP in the mouse testis, where androgens are highly expressed, immunohistochemistry and western blotting were performed. In the fetal testis, we found that moderate but consistent staining of SVIP is present in the cytoplasm of Leydig cells. In prepubertal and adult life, SVIP remains present in Leydig cells as well as in the cytoplasm of some peritubular and Sertoli cells. From postnatal day 15 onward, SVIP is strongly expressed in the cytoplasm of Leydig cells.Furthermore, TM3, MA-10 Leydig and Sertoli cell lines were also used to evaluate the expression of SVIP. To identify the interacting partners, such as steroidogenic acute regulatory (STAR) protein, colocalization studies were performed by fluorescence microscopy, showing that STAR colocalized with SVIP in the adult mouse testis. The expression changes of STAR were studied by using SVIP siRNAs in Leydig cell line cultures. Depletion of SVIP resulted in decreased expression of STAR. Additionally, the number and size of lipid droplets were significantly increased in SVIP-depleted Leydig cells. Taken together, our data identify SVIP as a marker of Leydig cell lineage and as a regulator of STAR protein expression and lipid droplet status in Leydig cells.     

Pseudo-natural products and natural product-inspired methods in chemical biology and drug discovery

Through evolution, nature has provided natural products (NPs) as a rich source of diverse bioactive material. Many drug discovery programs have used nature as an inspiration for the design of NP-like compound classes. These concepts are guided by the prevalidated biological relevance of NPs while going beyond the limitations of nature to produce chemical matter that could have unexpected or novel bioactivities. Herein, we discuss, compare, and highlight recent examples of NP-inspired methods with a focus on the pseudo-NP concept.     

International principles and standards for native seeds in ecological restoration

The growing demand for native seeds in ecological restoration and rehabilitation, whether for mining, forest, or ecosystem restoration, has resulted in a major global industry in the sourcing, supply, and sale of native seeds. However, there are no international guidance documents for ensuring that native seeds have the same standards of quality assurance that are regular practice in the crop and horticultural industries. Using the International Principles and Standards for the Practice of Ecological Restoration as a foundation document, we provide for the first time a synthesis of general practices in the native seed supply chain to derive the Principles and Standards for Native Seeds in Ecological Restoration (“Standards”). These practices and the underpinning science provide the basis for developing quality measures and guidance statements that are adaptable at the local, biome, or national scale. Importantly, these Standards define what is considered native seed in ecological restoration and highlight the differences between native seeds versus seeds of improved genetics. Seed testing approaches are provided within a logical framework that outline the many different dormancy states in native seed that can confound restoration outcomes. A “pro‐forma” template for a production label is included as a practical tool that can be customized for local needs and to standardize reporting to end‐users on the level of seed quality and germinability to be expected in a native seed batch. These Standards are not intended to be mandatory; however, the guidance statements provide the foundation upon which regulatory approaches can be developed by constituencies and jurisdictions.     

Lack of adequate seed supply is a major bottleneck for effective ecosystem restoration in Chile: friendly amendment to Bannister et al. (2018)

We argue that the need for a quality seed supply chain is a major bottleneck for the restoration of Chile's native ecosystems, thus supplementing the list of bottlenecks proposed by Bannister et al. in 2018. Specifically, there is a need for defining seed transfer zones, developing standards and capacities for properly collecting and storing seeds, reducing information gaps on seed physiology and longevity, and implementing an efficient seed supply chain with certification of seed origin and quality. Without such capacities, countries are unlikely to meet their restoration commitments. Although we focus on bottlenecks in Chile, the issues we raise are relevant to other countries and thus the global agenda for ecological restoration.     

Rewiring coral: Anthropogenic nutrients shift diverse coral–symbiont nutrient and carbon interactions toward symbiotic algal dominance

Improving coral reef conservation requires heightened understanding of the mechanisms by which coral cope with changing environmental conditions to maintain optimal health. We used a long‐term (10 month) in situ experiment with two phylogenetically diverse scleractinians (Acropora palmata and Porites porites) to test how coral–symbiotic algal interactions changed under real‐world conditions that were a priori expected to be beneficial (fish‐mediated nutrients) and to be harmful, but non‐lethal, for coral (fish + anthropogenic nutrients). Analyzing nine response variables of nutrient stoichiometry and stable isotopes per coral fragment, we found that nutrients from fish positively affected coral growth, and moderate doses of anthropogenic nutrients had no additional effects. While growing, coral maintained homeostasis in their nutrient pools, showing tolerance to the different nutrient regimes. Nonetheless, structural equation models revealed more nuanced relationships, showing that anthropogenic nutrients reduced the diversity of coral–symbiotic algal interactions and caused nutrient and carbon flow to be dominated by the symbiont. Our findings show that nutrient and carbon pathways are fundamentally “rewired” under anthropogenic nutrient regimes in ways that could increase corals’ susceptibility to further stressors. We hypothesize that our experiment captured coral in a previously unrecognized transition state between mutualism and antagonism. These findings highlight a notable parallel between how anthropogenic nutrients promote symbiont dominance with the holobiont, and how they promote macroalgal dominance at the coral reef scale. Our findings suggest more realistic experimental conditions, including studies across gradients of anthropogenic nutrient enrichment as well as the incorporation of varied nutrient and energy pathways, may facilitate conservation efforts to mitigate coral loss.     

丁酸调控幼龄反刍动物瘤胃上皮发育研究进展

瘤胃是反刍动物营养物质消化吸收和代谢的重要器官,其发育状态直接影响反刍动物生产性能和健康。初生犊牛和羔羊,瘤胃功能尚未发育完全,不能够充分消化和吸收固体饲料。因此,在幼龄时期,通过营养调控手段促进反刍动物的瘤胃发育对维持动物健康及提高生产性能具有重要意义。丁酸是瘤胃微生物降解植物性饲料的主要产物,也是瘤胃上皮及宿主的重要能量来源。丁酸调控幼龄反刍动物瘤胃上皮发育是一个历久弥新的话题。主要介绍了幼龄反刍动物瘤胃上皮形态及功能的发育以及丁酸调控幼龄反刍动物瘤胃上皮发育的研究进展。     

14种中国典型极小种群野生植物繁育特性和人工繁殖研究进展

繁殖是植物种群更新与维持的重要环节。包括极小种群野生植物在内的受威胁物种, 其濒危原因是在长期演化过程中自身繁育力的衰退、生活力的下降等内在因素和人类的过度采挖和生境的破坏等外在因素共同作用的结果。对极小种群野生植物进行高效的人工繁殖, 能扩大种群数量并应用于迁地保护、自然回归和满足商品市场的需求, 有利于其种质资源的保护和可持续利用。为了保持物种的遗传多样性, 采用种子繁殖育苗是有效的方法, 扦插、嫁接和组织培养技术等无性繁殖方法则可用于对难以用种子繁殖的种类进行快速繁殖。本文对14种中国典型极小种群野生植物的繁殖特性和已有的人工繁殖方法进行了综述, 并简要介绍在其种苗繁殖研究方面取得的进展。其中利用播种繁殖成功的物种有12种, 共繁殖230,000株种苗; 利用扦插繁殖成功的物种有5种, 共繁殖33,100株种苗; 华盖木(Manglietiastrum sinicum)、河北梨(Pyrus hopeiensis)和黄梅秤锤树(Sinojackia huangmeiensis)采用嫁接繁殖出了2,415株种苗; 9个物种的组织培养技术获得成功, 共繁殖了24,850株种苗。这些种苗有些已应用于迁地保护和自然回归。上述研究结果为这14种极小种群野生植物的保护和利用提供了理论和技术基础, 也能为其他极小种群野生植物的保护和利用提供参考。