Pectin—a product of citrus waste

The annual processing of citrus fruit wastes in the United States has reached two million tons. Forty thousand tons of pectin could be produced, compared with current production of three thousand tons. The physical and chemical properties of pectic substances are important botanically and industrially. Pectic substances aid in maintaining texture of fruits and vegetables and serve as jellying agents in preserves. The availability of increasing amounts of citrus wastes, combined with improvements in manufacturing techniques and new uses, promises expansion of industries concerned with pectin production and utilization.     

Mycorrhiza in sedges—an overview

Most terrestrial plants associate with root-colonising mycorrhizal fungi, which improve the fitness of both the fungal and plant associates. However, exceptions exist both between and within plant families failing to associate with mycorrhizal fungi or in the incidence and the extent of mycotrophy, which may vary greatly. Sedges are important pioneers of disturbed habitats and often dominate vegetations like wetlands, and arctic and alpine vegetations, in which the mycorrhizal inoculum in the soil is often low or absent. In the past, sedges were often designated as non-mycorrhizal, though limited reports indicated the presence of mycorrhiza in certain species. However, studies since 1987 indicate widespread occurrence of mycorrhiza in sedges. Based on these studies, the family Cyperaceae is no longer a non-mycorrhizal family, but the mycorrhizal status of its members is greatly influenced by environmental conditions. Further, sedges appear to have several morphological adaptations to thrive in the absence of mycorrhizal association. Though mycorrhizal associations have been noted in many sedge species, the ecological role of this association is not well documented and no clear generalisation can be drawn. Similarly, the role of mycorrhizal fungi on sedge growth and nutrient uptake or non-nutritional benefits has yet to be fully ascertained. This paper reviews the current information available on the incidence of mycorrhiza in sedges and the possible reasons for low mycotrophy observed in this family.     

Invasive species in China — an overview

China is a vast country with rich biodiversity, which makes China especially vulnerable to invasive species. It has a long history of introduction of non-native species, especially those with perceived beneficial impacts. Its rapid economic development, including an explosive growth in international trade and transportation, has increased the potential for new introductions. Currently, alien species are widespread in the country, occur in many ecosystems, represent most major taxonomic groups, and are introduced unintentionally as well as intentionally for cultivation. The paper lists various cases of invasive species which have caused significant threats or damages to local natural or artificial ecosystems, and indicates that two example industries (fresh water fisheries and lawn grasses) have brought or tend to bring in many invasive species and hence have caused or will cause changes and loss of biodiversity in local ecosystems. Based on these studies, it is suggested that China combat the problem through enhancing awareness, development of a database on invasive species, strengthening international co-operation, preparing case studies and introducing the necessary legislation, regulations and monitoring.     

Apoptosis in Alzheimer's disease—an update

Alzheimer's disease (AD) is the most common human neurodegenerative disorder characterized by the progressive deterioration of cognition and memory in association with the presence of senile plaques, neurofibrillary tangles, and massive loss of neurons. Most cases of AD are late-onset and sporadic, but in some cases the disease is inherited as an autosomal dominant trait. Four different genes, the amyloid precursor protein, apolipoprotein E, and presenilins 1 and 2 have been implicated in the etiology of familial AD. It is now generally accepted that massive neuronal death due to apoptosis is a commmon characteristic in the brains of patients suffering from neurodegenerative diseases, and apoptotic cell death has been found in neurons and glial cells in AD. This review summarizes the current findings regarding the evidence for apoptosis in AD and discusses the possible involvement of apoptosis-regulating factors in the pathology of AD. Modification of the apoptotic cascade could be considered as a primary therapeutic strategy for the disease.     

The Puerto Rican chironja—new all- purpose citrus fruit

The chironja, an apparent natural cross of grapefruit and orange, combines the flavors and other highly desirable characteristics of both parents, offering vast new possibilities for development, both for fresh market and industrial purposes.     

Bipolar budding in yeasts — an electron microscope study

Bud formation in yeasts with bipolar budding was studied by electron microscopy of thin sections.Budding in yeasts of the speciesSaccharomycodes ludwigii, Hanseniaspora valbyensis andWickerhamia fluorescens resulted in concentric rings of scar ridges on the wall of the mother cell. The wall between the ridges consisted of the scar plug left by the former budding and opened up in the formation of the next bud. The wall of the bud arose from under the wall of the mother cell.In the yeasts of the speciesNadsonia elongata more than one bud might be formed from the same plug.InSchizoblastosporion starkeyi-henricii the scar ridges were close together and apparently not separated by the entire plug.In all species a cross wall was formed between mother cell and bud which consisted of an electron-light layer between two layers of more electron-dense material. The cells separated along the light layer.The authors wish to thank Dr J. A. Barnett for corrections of the English text, and Mr J. Cappon for drawing Fig. 1.     

Production of 1,5-anhydro-d-fructose by an α-glucosidase belonging to glycoside hydrolase family 31

α-1,4-Glucan lyases [glycoside hydrolase family (GH) 31] catalyze an elimination reaction to form 1,5-anhydro-d-fructose (AF), while GH31 α-glucosidases normally catalyze a hydrolytic reaction. We determined that a small amount of AF was produced by GH31 Aspergillus niger α-glucosidase from maltooligosaccharides by elimination reaction, likely via an oxocarbenium ion intermediate.     

Psychosocial risk factors’ impact pathway for social life cycle assessment: an application to citrus life cycles in South Italy

The International Journal of Life Cycle Assessment - Social life cycle assessment (SLCA) was the last tool to be developed within the framework of life cycle thinking, and since the beginning,...     

Annelid aminotransferase activity—an exercise in basic biochemical skills

A practical exercise is described that allows students to investigate a specific problem using a variety of biochemical techniques. The need for a thorough understanding of the theoretical principles underlying these processes is emphasized. A suggested programme of private study and assessment is included to enable the progress of students to be followed.     

The history of comparative anatomy in Jena — an overview

Summary Comparative anatomy and zoology both have long academic traditions in Jena. At first, the two subjects developed in parallel and had many similarites in research topics. This development is covered in the first part of the paper. The close relationship between the two subjects started to break apart when Carl Gegenbaur and Ernst Haeckel were active at Jena University. In 1865 Haeckel became the first full professor of zoology in Jena, and zoology became more independent from comparative anatomy. In the second part of our paper, we follow the developments in comparative anatomy in Jena from Gegenbaur’s immediate students up until the end of Hans B?ker’s tenure in Jena in the mid-1930s. Certain subjects are in focus throughout this period, for example vertebrate head morphology and development, (the “head problem”), the relationship between anatomy and biology, and evolutionary questions. Some of these subjects have remained important research topics in zoology and comparative anatomy in Jena until the present day.     

Chronic exposure to cobalt compounds — an in vivo study

An in vivo experimental model for testing the effects of long-term chronic treatment with cobalt(II) compounds — cobalt chloride (CoCl₂) and cobalt-EDTA (Co-EDTA) on mice at different stages of development was optimized. Pregnant mice and their progeny were treated with daily doses of 75 or 125 mg kg^?1 body weight until postnatal day 90. The compounds were dissolved in regular tap water. Mice were sacrificed on days 18, 25, 30, 45, 60 and 90 after birth, which correspond to different stages of their development. Altered organ weight indices (calculated as a ratio of organ weight to body weight) of spleen, liver and kidneys, were found depending on the type of compound used, dose, duration of treatment, and the age of the animals. The results also showed significant accumulation of cobalt ions in blood plasma, spleen, liver and kidneys of the exposed mice. More Co(II) was measured in the organs of the immature mice (day 18, 25 and 30 pnd) indicating that they were more sensitive to treatment.     

Secular oscillations in the stratigraphic record—an acute debate

Work on secular oscillations of the ocean-atmosphere system has reached a particularly interesting stage, characterized by competing models that alternately invoke endogenic and celestial drivers. The most widely accepted concept is the icehouse-greenhouse cycle with an approximate length of 300 Ma. The concept holds that in the past 600 Ma the Earth has oscillated between a glacial mode and one of rather warm, equable climate; correlative changes in mineralogy of marine carbonates and evaporites as well as abundance of igneous intrusions point to an endogenic cause, most probably variations in the rates of plate motion and mantle convection that modulate sea level and the level of atmospheric CO₂ and thus climate. However, the 300-Ma icehouse-greenhouse cycle leaves important data unexplained. The history of glaciations as well as certain climate indicators, such as sea-surface temperatures derived from oxygen isotopes, indicate oscillations with wave lengths of 130–150 Ma. Such oscillations have been observed in the reconstructed cosmic-ray flux of the past 1000 Ma; they may modulate climate via low-level cloud cover. The debate about long-term climate oscillations poses several distinct questions for sedimentary geologists.     

Family 4 glycoside hydrolases are special: The first β-elimination mechanism amongst glycoside hydrolases

The glycoside hydrolases are a large group of enzymes that can be grouped into two major mechanistic classes based upon the stereochemical outcome of catalysis: retention and inversion of sugar anomeric configuration. Both mechanisms involve nucleophilic displacement at the anomeric center, and both proceed via positively charged oxocarbenium ion-like transition states. Exceptions to this are the Family 4 glycoside hydrolases (GH4), which display an unusual requirement for NAD⁺ and a divalent metal for activity. In addition, Family 4, uniquely, contains both α- and β-glycosidases. A novel mechanism is proposed for all GH4 members, featuring a redox-elimination-addition sequence, and involving anionic transition states to effect hydrolytic cleavage of the glycosidic linkage.     

Controlled replication of ‘Candidatus Liberibacter asiaticus‘ DNA in citrus leaf discs

‘Candidatus Liberibacter asiaticus’ is a fastidious bacterium and a putative agent of citrus greening disease (a.k.a., huanglongbing, HLB), a significant agricultural disease that affects citrus fruit quality and tree health. In citrus, ‘Ca. L. asiaticus’ is phloem limited. Lack of culture tools to study ‘Ca. L. asiaticus’ complicates analysis of this important organism. To improve understanding of ‘Ca. L. asiaticus’–host interactions including parameters that affect ‘Ca. L. asiaticus’ replication, methods suitable for screening pathogen responses to physicochemical and nutritional variables are needed. We describe a leaf disc-based culture assay that allows highly selective measurement of changes in ‘Ca. L. asiaticus’ DNA within plant tissue incubated under specific physicochemical and nutritional conditions. qPCR analysis targeting the hypothetical gene CD16-00155 (strain A4) allowed selective quantification of ‘Ca. L. asiaticus’ DNA content within infected tissue. ‘Ca. L. asiaticus’ DNA replication was observed in response to glucose exclusively under microaerobic conditions, and the antibiotic amikacin further enhanced ‘Ca. L. asiaticus’ DNA replication. Metabolite profiling revealed a moderate impact of ‘Ca. L. asiaticus’ on the ability of leaf tissue to metabolize and respond to glucose.