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Development of a Methodology to Determine Antibiotic Concentrations in Water Samples Using High-Pressure Liquid Chromatography 高压液相色谱法测定水样中抗生素浓度方法的建立
Journal of young investigators Pub Date : 2017-06-01 DOI: 10.22186/jyi.33.1.19-27
Tahnee Qualls, C. Agouridis, M. Kulshrestha
{"title":"Development of a Methodology to Determine Antibiotic Concentrations in Water Samples Using High-Pressure Liquid Chromatography","authors":"Tahnee Qualls, C. Agouridis, M. Kulshrestha","doi":"10.22186/jyi.33.1.19-27","DOIUrl":"https://doi.org/10.22186/jyi.33.1.19-27","url":null,"abstract":"JYI | June 2017 | Vol. 33 | Issue 1 © Qualls, Agouridis, Kulshrestha 2017 application of manure is the main pathway for veterinary antibiotic introduction into the terrestrial and aquatic environments. In agriculture, antibiotics are used for both therapeutic as well as non-therapeutic purposes. The two main non-therapeutic uses of antibiotics in livestock are growth additives and illness prevention (Shore, & Pruden, 2009). Estimates are that 11 million kg of antibiotics were used in 2002 along for non-therapeutic uses (Davis et al., 2006). Unfortunately, large amounts of administered antibiotics are not metabolized by animals but instead are excreted in manure. Rates of unmetabolized antibiotics are as high 70-90% as in the case of tetracyclines, which are one of the most used classes of antibiotics (Kumar Gupta, Chander, & Singh, 2005; USEPA, 2013). Manures are commonly applied across croplands as part of farm nutrient management plans. Hence, the antibiotics in these manures are land applied as well. Once applied to the land, antibiotics are transported to surface waters, via runoff, or ground waters, through infiltration. To date, only a limited amount of research has been conducted on the transport of antibiotics in the runoff, but this research indicates that the mechanisms of transport vary with antibiotic type. Some antibiotics bind to and are transported with soil, while others do not (Tolls, 2001). Limited studies have examined the use of best management practices (BMPs), such as vegetated filter strips, and the addition of alum to minimize antibiotic transport (Enlow, 2014; DeLaune, & Moore, 2013; Lin et al., 2011). INTRODUCTION The U.S. Environmental Protection Agency (USEPA) classifies antibiotics as a contaminant of emerging concern (CEC) because they are detected in the environment at higher than expected levels and may negatively impact human and aquatic ecosystems (USEPA, 2013). The risk these antibiotics pose to humans and aquatic life is not known; however, the primary concern is that the antibiotic-resistant strains of bacteria will develop. Utilization in human healthcare and livestock care are the two main sources of antibiotics in the environment. Unlike human waste, which is treated via treatment plants or septic systems, livestock waste is oftentimes directly applied to the land as part of a nutrient management plan (NRCS, 2012). Baguer, Jensen, and Krogh (2000) noted that land Development of a Methodology to Determine Antibiotic Concentrations in Water Samples Using High-Pressure Liquid Chromatography","PeriodicalId":74021,"journal":{"name":"Journal of young investigators","volume":"33 1","pages":"19"},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47936009","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Comparison of Dark Matter Proportions Across Types of Spiral Galaxies 不同类型螺旋星系中暗物质比例的比较
Journal of young investigators Pub Date : 2017-06-01 DOI: 10.22186/jyi.33.1.1-7
M. Williams, A. Lovell
{"title":"Comparison of Dark Matter Proportions Across Types of Spiral Galaxies","authors":"M. Williams, A. Lovell","doi":"10.22186/jyi.33.1.1-7","DOIUrl":"https://doi.org/10.22186/jyi.33.1.1-7","url":null,"abstract":"","PeriodicalId":74021,"journal":{"name":"Journal of young investigators","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46488353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Varying sugars and sugar concentrations influence in vitro pollen germination and pollen tube growth of cassia alata l. 不同糖和糖浓度对决明子离体花粉萌发和花粉管生长的影响。
Journal of young investigators Pub Date : 2017-06-01 DOI: 10.22186/jyi.33.1.42-45
Anjela J. Lagera, L. O. Balinado, John Rex Baldomero, Hannah Fae I. Rotairo, Nariza L. Tero, Mailyn S. Maghinay, Irma F. Baluyo, Mary Rose Reyes, R. Galve, Shellie Ann Sibao, Jeramie V. Rufino
{"title":"Varying sugars and sugar concentrations influence in vitro pollen germination and pollen tube growth of cassia alata l.","authors":"Anjela J. Lagera, L. O. Balinado, John Rex Baldomero, Hannah Fae I. Rotairo, Nariza L. Tero, Mailyn S. Maghinay, Irma F. Baluyo, Mary Rose Reyes, R. Galve, Shellie Ann Sibao, Jeramie V. Rufino","doi":"10.22186/jyi.33.1.42-45","DOIUrl":"https://doi.org/10.22186/jyi.33.1.42-45","url":null,"abstract":"(Baloch & Lakho, 2001). Most of the studies conducted on C. alata L. are on its therapeutic properties. Leaves of C. alata L. contain anthraquinone derivatives which exhibit antimicrobial, antitumor, antioxidant, cytotoxic and hypoglycemic activities (Alalor, Igwilo, & Jeroh, 2012). Crude extracts of the plant are being used to treat various skin diseases (Balinado, & Chan, 2017) and are effective against Staphylococcus aureus and Bacillus subtilis (Alalor, Igwilo, & Jeroh, 2012). Also, C. alata L. based soap was proven effective against opportunistic yeasts (Esimone, 2007). Preliminary investigation of the developmental morpho-anatomy of the male gametophyte of C. alata L. was already conducted (Tolentino, 2011), but limited information is known regarding its sugar metabolism and investigating this will immensely contribute to the extensive cultivation of the plant taking into consideration its medicinal properties. This study, therefore, would add light to the developmental biology of C. alata particularly to its pollen germination and pollen tube growth. The study specifically aims to determine the effect of varying sugars and sugar concentrations on the in vitro pollen germination and tube growth of C. alata by calculating the germination percentage and measuring the pollen tube length after exposure to different sugars. In numerous studies on in vitro pollen germination of different plant species, sucrose exhibited strong stimulatory effects (Baloch, & Lakho, 2001; Patel, 2017; Zhang, & Croes, 1982), together with glucose and lactose (Ismail, 2014); thus, may also promote pollen germination in C. alata. Maltose and fructose, on the other hand, were reported to have varied effects on pollen germination of various plant species (Ismail, 2014; Okusaka, & Hiratsuka, 2009; Nakamura, & Suzuki, 1985). INTRODUCTION The total count of pollen grains on a stigma usually surpasses the number required to fertilize all ovules; thus, the process of pollen growth in the carpel is highly competitive (Okusaka & Hiratsuka, 2009). In higher plants, the elongation of pollen tube is extremely fast making the pollen tube the plant cell with the fastest growth rate. Accordingly, this swift growth of pollen tubes is essential for male reproductive success (Okusaka, & Hiratsuka, 2009) and for the subsequent plant development. Pollen development and tube growth (due to its high growth rate) are high energy-requiring processes (Selinski, & Scheibe, 2014). Carbohydrates act as energy source during the two processes (Okusaka, & Hiratsuka, 2009). The storage compounds and sugars stored in mature pollen can adequately sustain survival of pollen and germination; however, the rapid pollen tube elongation requires secretions of carbohydrates (exogenous sugars) from the stylar canal to proceed (Reinders, 2016). Exogenous sugars also provide and maintain suitable osmotic environment not only for germination of pollen but also for sustained pollen tube growth Varying Sugars and ","PeriodicalId":74021,"journal":{"name":"Journal of young investigators","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46887286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 3
A transcriptome study of borrelia burgdorferi infection in murine heart and brain tissues 伯氏螺旋体感染小鼠心脑组织的转录组研究
Journal of young investigators Pub Date : 2017-06-01 DOI: 10.22186/jyi.33.1.28-41
Maureen A. Carey, Eric S. Ho
{"title":"A transcriptome study of borrelia burgdorferi infection in murine heart and brain tissues","authors":"Maureen A. Carey, Eric S. Ho","doi":"10.22186/jyi.33.1.28-41","DOIUrl":"https://doi.org/10.22186/jyi.33.1.28-41","url":null,"abstract":"during the tick’s blood meals (Rosa et al., 2005). Although Lyme disease is usually curable with prompt antibiotic treatment, nonspecific symptoms make early diagnosis difficult, and untreated infection can induce rheumatic, cardiac, and neurologic complications. The current screening test is still suboptimal in detecting Lyme reliably (Centers for Disease, & Prevention, 1995; Dressler et al., 1993). Lyme is often diagnosed after the emergence of the classic bulls-eye-shaped rash at the site of the tick bite, which occurs in over 70% of patients (McConville, 2014). The infection spreads throughout the body, causing general inflammation during the early dissemination stage, and years after initial infection, painful arthritis and joint swelling are observed among 60% of patients (McConville, 2014). Borrelia are transported throughout the body, and persistent infections are established in the skin, joint, heart, bladder, and, in only humans and primates, the central nervous system (Rosa et al., 2005). Some of these tissues are particularly affected by infectioninduced inflammation. Lyme carditis (inflammation of the heart tissue, interfering with its electrical activity) occurs in 4-10% of infections during the early dissemination stage. Carditis responds well to antibiotic treatment; however, because it occurs so early in the infection process and Lyme disease is difficult to diagnose, it can be fatal (McAlister et al., 1989). Additionally, 10-15% of Lyme disease cases manifest neurological conditions, such as pain caused by temporary or permanent inflammation of the nerves, meningitis, memory and anxiety problems, depression, and both cranial and peripheral neuritis (Narasimhan et al., 2003; Pachner, & Steere, 1984; Rupprecht et al., 2008). Some patients will experience Post-Treatment Lyme Disease INTRODUCTION Lyme disease is prevalent from southern Scandinavia to the northern Mediterranean countries and in the northeastern United States (U.S.). In the U.S., Lyme disease is the most common vector-borne disease: over 251,000 cases were reported between 2005 and 2014, with about 25,000 confirmed cases each year. Most cases occur in the northeast; however, notable expansion was observed in the Great Lakes region (CDC 2014). Lyme disease is caused by the infection of Borrelia burgdorferi sensu lato (family Spirochaetaceae), a diderm, microaerophilic spirochete bacteria (Wang et al., 1999). Within the genus Borrelia, three other species (B. afzelii, B. garinii, and possibly B. valaisiana) can cause the disease, but are more prevalent on the European continent (WHO, 2006). Other Borrelia species are carried by soft-bodied ticks and cause relapsing fevers (Garcia-Monco et al., 1997). All four pathogenic species of Borrelia are spread to humans by the bite of an infected tick. In the U.S., two blacklegged, or deer, tick species (Ixodes scapularis and Ixodes pacificus) are known to carry B. burgdorferi. The bacteria infect several mammal and bird species ","PeriodicalId":74021,"journal":{"name":"Journal of young investigators","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46192733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The efficacy of aqueous false yam (icacina oliviformis) tuber extract against cowpea aphids (aphis craccivora koch) 假山芋块茎提取物对豇豆蚜的防治效果
Journal of young investigators Pub Date : 2017-04-01 DOI: 10.22186/jyi.32.3.7-22-24
Theophilus Y. Alale, N. Opoku, C. Adarkwah
{"title":"The efficacy of aqueous false yam (icacina oliviformis) tuber extract against cowpea aphids (aphis craccivora koch)","authors":"Theophilus Y. Alale, N. Opoku, C. Adarkwah","doi":"10.22186/jyi.32.3.7-22-24","DOIUrl":"https://doi.org/10.22186/jyi.32.3.7-22-24","url":null,"abstract":"beneficial insect species, which is a threat to human health and environmental hazards. This calls for the search and use of environmentally friendly biopesticides instead of conventional pesticides to control aphid’s outbreak (Leake, 2000). False yam tuber (Icacina oliviformis) extract has been shown to have some toxic compounds that need to be investigated to find its effect on cowpea aphid. Its effect on aphids has been attributed to the presence of inhibitory factors (resins) which make sap unpleasant to feed on (Dei, Bacho, Adeti, & Rose, 2011). The false yam plant’s year-round availability makes it economically affordable to be used as a substitute biopesticide for the conventional pesticides. This study investigates the efficacy of aqueous false yam tuber extract used as a biopesticide as an alternative for chemical pesticides against cowpea aphids.","PeriodicalId":74021,"journal":{"name":"Journal of young investigators","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49366768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
The in vitro Studies of the Inhibitory Effect of Green Tea (Camellia sinensis) on Pseudomonas aeruginosa Treated Contact Lenses 绿茶对铜绿假单胞菌治疗隐形眼镜抑制作用的体外研究
Journal of young investigators Pub Date : 2017-04-01 DOI: 10.22186/jyi.32.4.25-29
M. Bigaud, Anna K. Yeung-Cheung
{"title":"The in vitro Studies of the Inhibitory Effect of Green Tea (Camellia sinensis) on Pseudomonas aeruginosa Treated Contact Lenses","authors":"M. Bigaud, Anna K. Yeung-Cheung","doi":"10.22186/jyi.32.4.25-29","DOIUrl":"https://doi.org/10.22186/jyi.32.4.25-29","url":null,"abstract":"","PeriodicalId":74021,"journal":{"name":"Journal of young investigators","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49308689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Addition of zinc, manganese, and iron to growth media triggers antibiotic production in bacterial isolates fron the lower atmosphere 在生长培养基中添加锌、锰和铁会引发低层大气中细菌分离株产生抗生素
Journal of young investigators Pub Date : 2017-03-01 DOI: 10.22186/jyi.32.2.7-11
Quinn Washburn, S. Spradlin, C. Weber
{"title":"Addition of zinc, manganese, and iron to growth media triggers antibiotic production in bacterial isolates fron the lower atmosphere","authors":"Quinn Washburn, S. Spradlin, C. Weber","doi":"10.22186/jyi.32.2.7-11","DOIUrl":"https://doi.org/10.22186/jyi.32.2.7-11","url":null,"abstract":"antibiotics often point to Actinomycetales (Bérdy, 2012; Goodfellow & Fiedler, 2010). Goodfellow & Fiedler (2010) stated that by using selective techniques, such as sampling from understudied and extreme environments, novel Actinobacteria may be discovered. One such environment, is the lower atmosphere (Weber and Werth, 2015), which is defined by as the first 20km above ground level (Womack, Bohannan, & Green 2010). A multitude of both culture-dependent and culture-independent studies demonstrate that Actinobacteria are an omnipresent component of the aerial environment (Bowers et al., 2011; Fahlgren, Hagström, Nilsson, & Zweifel, 2010; Polymenakou, 2012; Shaffer & Lighthart, 1997; Weber & Werth, 2015). The lower atmosphere has several distinct advantages in the search for novel Actinomycetales. The lower atmosphere is a highly variable environment (Fahlgren et al., 2010) with dramatically oscillating temperatures (-56°C to 15°C), low relative humidity and high levels of ultraviolet radiation (Womack, Bohannan, & Green, 2010). These conditions may select for Actinomycetales over faster-growing bacterial taxa, such as many Proteobacteria (Weber & Werth, 2015). Exploring the lower atmosphere, given its potential to harbor antibiotic-producing bacteria, with selective cultivation methods may lead to the discovery of novel species and antibiotics. While not as commonly studied for their antibiotic-producing capabilities, Bacillus is another genus of bacteria that contains antibiotic-producing members and is commonly found in the lower atmosphere (Athukorala, Dilantha Fernando, & Rashid, 2009; Fahlgren et al., 2010; Shaffer & Lighthart, 1997). Another approach to discover novel antibiotic compounds is to place a single organism under a wide array of culture conditions INTRODUCTION According to the World Health Organization (2015), pathogens are becoming more antibiotic-resistant than ever before, which is a problem caused and exacerbated by the overuse and misuse of existing antibiotics. As a result, there is a desperate need for novel antibiotics, but the approval rate of clinical antibiotics continues to decline (Donadio, Maffioli, Monciardini, Sosio, & Jabes, 2010). The order Actinomycetales within the phylum Actinobacteria, includes the genus Streptomyces, which produces two-thirds of known antibiotics (Barka et al., 2016; Watve, Tickoo, Jog, & Bhole, 2001). This genus is predicted to produce 150,000 to almost 300,000 antimicrobial compounds still awaiting discovery (Watve et al., 2001). Therefore, predictions about the next source of novel Addition of Zinc, Manganese, and Iron to Growth Media Triggers Antibiotic Production in Bacterial Isolates From the Lower Atmosphere","PeriodicalId":74021,"journal":{"name":"Journal of young investigators","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48643820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
rClone: a synthetic biology tool that enables the research of bacterial translation r克隆:一种能够研究细菌翻译的合成生物学工具
Journal of young investigators Pub Date : 2017-03-01 DOI: 10.22186/jyi.32.3.7-12-19
Anthony J. Eckdahl, R. Neal, A. M. Campbell, T. Eckdahl
{"title":"rClone: a synthetic biology tool that enables the research of bacterial translation","authors":"Anthony J. Eckdahl, R. Neal, A. M. Campbell, T. Eckdahl","doi":"10.22186/jyi.32.3.7-12-19","DOIUrl":"https://doi.org/10.22186/jyi.32.3.7-12-19","url":null,"abstract":"mRNA, called the ribosome binding site (RBS; Figure 1). After the small ribosomal subunit binds to the RBS, the large ribosomal subunit attaches to the small subunit to begin translation of the mRNA into a chain of amino acids. The mRNA bases are read as triplet codons that interact by base pairing with anticodons in transfer RNA (tRNA) molecules, which carry amino acids to the growing protein chain (Malys & McCarthy, 2010). As shown in Figure 1, RNA-RNA base pairing typically involves the Watson-Crick base pairs of G with C, and A with U, but G can also base pair with U. The conventional understanding is that the strength of a given RBS is determined by the strength of its base pairing interactions with the 16S rRNA (Shine & Dalgarno, 1974). In natural bacterial genomes, there is a wide variety of RBS sequences and RBS translational strengths that have resulted from natural selection for global patterns of gene expression. The relationship between RNA base pairing and the strength of an RBS also explains how synthetic RBSs can be produced with widely varying strengths. In addition to intermolecular base pairing, intramolecular base pairing affects the strengths of RBSs. The ability of RNA to engage in intramolecular base pairing is well established (Busan & Weeks, 2013). RBS elements can be disabled by intramolecular RNA folding, as is the case in riboswitches (Breaker, 2012). The RNA in riboswitches adopts an OFF state when the RBS is bound by a complementary anti-RBS sequence within the mRNA. For the ON state, a small molecule ligand binds to the folded RNA and changes the RNA shape so that the RBS is available for interaction with the 16S rRNA. Understanding the function of RBSs informs the discipline of synthetic biology, which uses engineering principles and molecular cloning methods for the construction of parts, devices, and systems, INTRODUCTION Gene expression, the process by which the inherited information of genes is used to direct the function of cells, is regulated in all cells because not all genes are needed all the time or under all circumstances (Hijum, Medema, & Kuipers, 2009). Gene expression begins with transcription, the process by which the DNA base sequence of a gene is converted into RNA sequence information. For genes that encode proteins, the messenger RNA (mRNA) product of transcription is used during translation to encode the sequence of amino acids in a protein. The sequence of bases in mRNA is translated by the ribosome, which is composed of a large (50S) and a small (30S) subunit. Translation is initiated when the 16S ribosomal RNA (rRNA) of the small ribosomal subunit base pairs to a conserved sequence in the rClone: A Synthetic Biology Tool That Enables the Research of Bacterial Translation","PeriodicalId":74021,"journal":{"name":"Journal of young investigators","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45258033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Response of Acacia tortilis to Elephant Browsing in Tarangire National Park, Tanzania: Possible Above-Ground Compensation? 坦桑尼亚塔兰吉雷国家公园,金合欢对大象觅食的反应:可能的地上补偿?
Journal of young investigators Pub Date : 2017-01-01 DOI: 10.22186/jyi.32.1.1-6
Joanne E Johnson, J. J. Ebersole
{"title":"Response of Acacia tortilis to Elephant Browsing in Tarangire National Park, Tanzania: Possible Above-Ground Compensation?","authors":"Joanne E Johnson, J. J. Ebersole","doi":"10.22186/jyi.32.1.1-6","DOIUrl":"https://doi.org/10.22186/jyi.32.1.1-6","url":null,"abstract":"keystone savanna species. There are many variables in woody savanna which affect the productivity of trees, including Acacia spp. Disease decreases growth, rainfall increases growth, and fire has variable effects on growth based on the severity of the fire and the characteristics of various Acacia species (Dharani et al., 2009; Fornara, 2008; Mopipi et al., 2009; Otieno, Kinyamario & Omenda, 2001; Scogings, Johansson, Hjalten & Kruger, 2012). However, effects of herbivory and the dynamic interactions between browsers and woody plants have been heavily disputed. Several researchers found that intense large herbivore browsing results in compensatory aboveground plant growth and can lead to alternative stable states (Dublin, Sinclair & McGlade, 1990; Jachmann & Bell, 1985; Smallie & O’Connor, 2000). However, others have found that large herbivore populations, such as elephants (Loxodonta africana) or giraffes (Giraffa camelopardalis), have a negative effect on woody vegetation growth (Guldemond & Van Aarde, 2008; Chira & Kinyamario, 2009; Pellew 1984). Past findings on the effects of browsing on sub-Saharan African Acacia species vary by mammal, tree species and response measurement. Browsing by non-elephant large mammals resulted in compensatory growth, leading to higher stem diameter growth of A. xanthophloea (Dharani et al., 2009). Similarly, simulated browsing of A. xanthophloea, A. tortilis, A. hockii (Pellew, 1984) and A. karroo (Stuart-Hill & Tainton, 1989) resulted in increased shoot growth and competitive ability when defoliation rates were between 25-50%. Du Toit, Bryant & Frisby (1990) and Chira & Kinyamario (2009) respectively found that heavy browsing by elephants led to an increase in shoot growth and higher nitrogen concentration in A. nigrescens foliage and coppice growth in A. INTRODUCTION Woody plants provide energy and nutrients for many mammals in African savannas. Throughout Africa, Acacia spp. trees provide the primary food source for numerous browsers, and also serve as important habitat for birds (Dharani, Kinyamario, Wagacha & Rodrigues, 2009). Many species, including black rhinoceros, giraffe, grey duiker, dik-dik, grysbok, klipspringer, gerenuk, dibatag, bushbuck, and kudu, feed exclusively on woody browse (OwenSmith, 1982). Because Acacia trees fix nitrogen, this also leads to higher forage quality in grasses underneath them compared to areas not under their canopies (Ludwig, De Kroon & Prins, 2008; Mopipi, Trollope & Scogings, 2009). Understanding the conditions that allow continued Acacia growth despite browsing will allow conservationists to monitor and prevent mortality of this Response of Acacia tortilis to Elephant Browsing in Tarangire National Park, Tanzania: Possible Above-Ground Compensation?","PeriodicalId":74021,"journal":{"name":"Journal of young investigators","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"68279248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Chronic Traumatic Encephalopathy: Connecting Mechanisms to Diagnosis and Treatment 慢性创伤性脑病:诊断和治疗的连接机制
Journal of young investigators Pub Date : 2017-01-01 DOI: 10.22186/jyi.33.4.83-86
Christy Milani, N. Jadavji
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