Life Sciences Commons^™

A Cytochemical Scanning Electron Microscopy Study Of Non-Specific Acid Esterase And Acid Phosphatase Activities In Human Peripheral Blood Lymphocytes, A. Campos, E. Fernández-Segura, J. M. García-López

Scanning Microscopy

We analyzed the distribution patterns of nonspecific acid esterase and acid phosphatase activities with cytochemistry-scanning electron microscopy in backscattered and secondary electron imaging modes in isolated normal human peripheral blood lymphocytes . The analysis of non-specific acid esterase activity in the backscattered electron imaging mode showed, in some cells, focal distribution with a well-defined, homogenous deposit. Two patterns of acid phosphatase activity were evident with the backscattered electron imaging mode, i.e., focal and granular. Peripheral blood lymphocytes showing focal activity of both enzymes presented a smooth surface with few scattered microvilli as seen with the secondary electron imaging mode ; while ...

Conventional And High Resolution Scanning Electron Microscopy Of Biological Sectioned Material, C. Scala, G. Cenacchi, P. Preda, M. Vici, R. P. Apkarian, Gianandrea Pasquinelli

Scanning Microscopy

Intracellular structures of embedded biological tissues (rat kidney, myocardium and small intestine) were observed by conventional-scanning electron microscopy (C-SEM) and high-resolution scanning electron microscopy (HR-SEM) after glass knife sectioning. C-SEM of semi -thin sections of material processed the same way as conventional transmission electron microscopy (TEM) provided strong backscattered electron (BSE)-dependent, two-dimensional secondary electron images (SEI(-)) which precisely integrated and further extended previous light microscopy (LM) observation of the same specimen. In addition, the three-dimensional (3-D) arrangement of intracellular organelles was appreciated using a mixture of acetone-soluble acrylic resin in place of epoxy resin embedding. Since the identification of ...

Cytology Of Pollutant Metals In Marine Invertebrates: A Review Of Microanalytical Applications, J. A. Nott

Scanning Microscopy

X-ray microanalysis (XRMA) is customized for investigations of the metabolic and detoxification strategies of heavy metals taken by marine organisms from polluted environments. Sites of uptake, intracellular accumulation, transport and excretion are visualized, analysed and quantified . Cryopreparation techniques are required to prevent the translocation or loss from specimens of soluble metal species.

In marine invertebrates, metals are detoxified by systems of chemical binding and intracellular compartmentalization. XRMA investigations have concentrated on marine molluscs and crustaceans and even within these restricted groups there are marked inter-species differences in the biochemical and cytological processes which reduce metal bioavailability. Some detoxification systems also ...

Phenotypic Subpopulations Of Macrophages And Dendritic Cells In Human Spleen, Patrick J. Buckley

Scanning Microscopy

Using immunohistochemical techniques and a large number of monoclonal antibodies, the presence and distribution of phenotypic subpopulations of macrophages (Mθs) and dendritic cells in human spleen were assessed. The results of this study show that different subsets of Mθs and dendritic cells are present in the spleen and that some of these occupy discrete microanatomic locations . In the red pulp (RP) certain antigens are expressed by different proportions of uniformly distributed Mθs in the cords . On the other hand, some antigens are present on Mθs that form clusters of variable size within the red pulp . These include CD11c, CD 15 ...

Innervation And Vascular Pharmacodynamics Of The Mouse Spleen, Frank D. Reilly

Scanning Microscopy

Neurohistochemical and in vivo and electron microscopic methods demonstrated α-and ,β-adrenergic receptors and adrenergic innervation in arterioles and "arterial" capillaries of the mouse spleen. Such innervation and receptors in venules and channels within the red pulp were sparse. Cholinergic innervation and receptors were judged to be absent in the microvasculature. Histamine elicited arteriolar dilation which was blocked by metiamide suggesting the presence of H₂ receptors. However , following blockade of H₂ receptors, histamine produced arteriolar constriction. Serotonin elicited only venular constriction. Lactic acid caused arteriolar constriction; bradykinin and prostaglandins (PG) E₂ and PGF_2α triggered arteriolar constriction, but ...

Agriculture News Release - 1990-12-21, United States. Congress. House. Committee On Agriculture, E. De La Garza

Kika de la Garza Congressional Papers - Agriculture Committee News Releases

No abstract provided.

Making Corn Replant Decisions, Garren O. Benson

Proceedings of the Integrated Crop Management Conference

When the stand of corn from the initial planting is not what a corn producer desired, whether or not to replant becomes an issue. Will the original stand or a replanted stand be the most profitable? The first step in determining the yield potential of the original stand involves taking detailed stand counts. This often is more complicated than simply counting plants, as factors such as plant health and stand uniformity often complicate things. The yield potential of the original stand must then be compared with what one expects from a replant. If a replant will yield more than the ...

Environmental Opportunities And Responsibilities For The 90'S, Craig I. Struve

Proceedings of the Integrated Crop Management Conference

Entering my third decade in the fertilizer and chemical business, I am amazed at how different each decade has been. During the early 70's the most important challenge we faced was feeding the world. We helped American agriculture go on a production binge, proving we had the capacity to produce what the world needed but lacked the resources to buy and distribute. We, of course, became awash in grain and during the early 1980's, we along with our customers, fought for our very survival. We have been on a twenty year roller coaster ride and have really had ...

Determining Herbicide Carryover Risk- How Close Can We Come?, Mark M. Loux

Proceedings of the Integrated Crop Management Conference

Crop injury resulting from herbicide carryover is a function of four variables: 1) the herbicide residue persisting from one year or crop to the next (or the herbicide concentration in soil at the time of planting); 2) the availability of the herbicide for uptake by the germinating seed, emerging seedling, or young plant; 3) the sensitivity of the follow crop to the herbicide; and 4) the environmental conditions in the early part of the growing season. These four factors interact to determine the potential for or the severity of injury due to carryover.

Demonstration Of A Weed Management Expert System For Crop Production, Edward E. Schweizer

Proceedings of the Integrated Crop Management Conference

Abstract. The employment of a computer model to facilitate weed management decisions has the potential to reduce herbicide use when weed densities are below an economical threshold as opposed to applying prophylactic herbicide treatments in anticipation of weed problems. The computer model was constructed by linking two submodels representing soil-applied and postemergence weed management decisions. The models are farm specific, user friendly, and consider most herbicide options and herbicide efficacy by weed species. The submodels were developed in LOTUS.

Herbicide Presistence In Soil, Mark M. Loux

Proceedings of the Integrated Crop Management Conference

Herbicides are applied directly to soils or plant foliage. Interaction of a herbicide with various living and non-living components of the environment ultimately determines how quickly it dissipates or degrades. Dissipation can be defined as the disappearance or loss of herbicide from the target site through a number of processes. Herbicide may move from the target site via processes such as runoff or leaching, or gradually degrade to undetectable or insignificant levels. Degradation, or alteration of the herbicide molecule by primarily chemical and biological processes, is thus one component of dissipation. Alternatively, we can distinguish between the transfer of herbicide ...

Soybean Cyst Nematode- Identification And Extraction Technique, Gregory L. Tylka

Proceedings of the Integrated Crop Management Conference

A major factor limiting soybean production in Iowa is parasitism by the soybean cyst nematode, Heterodera glycines. Soybean cyst nematode is now known to be present in 48 counties within Iowa. It is very likely that the nematode is present in many other counties as well, but the nonspecific nature of the above-ground symptoms of soybean cyst nematode damage makes early identification or diagnosis of infestations difficult.

Results Of Latest Water Quality Surveys, George F. Czapar

Proceedings of the Integrated Crop Management Conference

Recent state and national surveys have examined both groundwater and surface water quality. These studies have identified the contaminants that are most common, and where they are most likely to occur. This type of background information is critical so that management practices can be modified to protect groundwater and surface water from agricultural chemicals, and to better identify areas that are most vulnerable to contamination.

Biology And Management Of Bean Leaf Beetle In Soybean, Larry P. Pedigo, Michael R. Zeiss, Marlin E. Rice

Proceedings of the Integrated Crop Management Conference

The bean leaf beetle, Cerotoma trifurcata (Forster), is a widespread pest of soybean in the major crop production areas of the U.S. It has been a significant problem in the South but, until the last decade, was an infrequent problem in the Midwest. During earlier times, the major concern was early season invasion of soybean fields and localized problems of seedling defoliation. In the 1980's, however, grower reports of pod feeding were received, and these have increased significantly until the present. Indeed, today the bean leaf beetle has become the most consistently important insect problem on soybean in ...

Managing Alfalfa, Stephen K. Barnhart

Proceedings of the Integrated Crop Management Conference

Alfalfa is the most important forage crop grown in Iowa. It is an economical source of home grown protein, energy, minerals, and vitamins for livestock. High quality alfalfa allows producers to reduce dependency on protein supplements and feed grains, which translates into greater efficiency and profitability for the producer and better nutrition for the animal.

Biological Pest Controls: Possibilities For Improved Implementation In Iowa, David B. Orr

Proceedings of the Integrated Crop Management Conference

Chemical insecticides are the standard means for reducing populations of insect pests in agricultural and horticultural settings. However, government regulations are restricting the use of a variety of pesticides for many agricultural uses. The requirement of registration for all pesticides labelled before 1984 has already resulted in the cancellation of approximately 20,000 pesticide registrations in 1989. In addition, pest resistance to insecticides (over 400 species), and an increased sensitivity in the general public to possible environmental and health hazards are forcing the agricultural industry to search for alternatives to chemical control.

Long-Term Trends For Selected Iowa Weather Variables, Richard E. Carlson

Proceedings of the Integrated Crop Management Conference

In recent times, the state of climate earth is of concern to many people. Accounts of global warming, ozone holes, floods, droughts, and year-to-year variability of the weather in the decade of the SO's appear in popular media. Much attention has been focused on the possibility of growing crops in a changing environment (Rosenberg, 1981). Actual measurements of changing concentrations of trace gases in the atmosphere give credence to some of these fears (Schneider, 1990). Their actual impact on our weather is, however, controversial (Schneider, 1990). Computer models describing the atmosphere responding to these changes in gaseous composition predict ...

Adding Crop Consulting Services To Your Business, Dean Grundman

Proceedings of the Integrated Crop Management Conference

The increasing emphasis on production efficiency and environmental concerns has many farm suppliers considering offering crop management services to expand their businesses. While most agricultural suppliers have provided some agronomic services to customers, these services were often limited to soil fertility recommendations and investigating product performance or crop damage complaints. Adding a consulting service for hire is a major change of direction for many businesses and the transition can be difficult.

Fertilizer Placement Consideration For Conservation Tillage, R. M. Cruse

Proceedings of the Integrated Crop Management Conference

The environment surrounding plant roots is extremely complex and variable. For example, it is not uncommon for the surface one to two inches of soil to be very dry while very wet conditions exist at deeper areas within the root zone. Surface soil temperatures may differ by 20 °F or more from that observed at deeper layers within the rooting zone. A zone of compactions causes by wheel traffic may create very different conditions on one side of a crop row compared to the other side where no traffic occurs. The environmental variations occurring in the root zone tend to ...

Effects Of Previous Hybrid On Corn Yields The Following Year, I. C. Anderson, D. N. Sundberg

Proceedings of the Integrated Crop Management Conference

Approximately 25% of Iowa's annual 12.5 million acres of corn is grown where corn was grown the previous year. With adequate N fertilizer, corn following corn usually yields less than corn following soybeans or some other crop. The magnitude of this yield reduction usually is about 10%, but it varies between fields, locations and years. During 1988 in southeastern Iowa, farmers and researchers reported yield differences as great as 100 bufacre between the yield of corn after soybeans and corn after corn. There are many possible explanations for the rotation effect such as differences in residual soil moisture ...

Pesticide Drift: A Problem In Iowa?, Charles A. Eckermann

Proceedings of the Integrated Crop Management Conference

Pesticide drift ranks as the most frequent incident reported to the Iowa Department of Agriculture and Land Stewardship (IDALS). Pesticide drift, as defined by the U.S. Environmental Protection Agency (EPA) 40 CFR 162.3, means "any movement of a pesticide during or immediately after application or use through air to a site other than the intended site of application or use."

Soybean Cyst Nematode- Biology Management, Gregory L. Tylka

Proceedings of the Integrated Crop Management Conference

The soybean cyst nematode, Heterodera glycines, is a small, unsegmented plant-parasitic roundworm that attacks the roots of soybeans. While many plant-parasitic nematodes are believed to be endemic or native to the United States, the soybean cyst nematode was apparently introduced from Japan. Soybean cyst nematode was first discovered in the United States in 1954 in North Carolina. It has since spread to 25 additional states in the Southeast and Midwest. It was first discovered in Iowa in Winnebago County in 1978. The presence of soybean cyst nematode has been confirmed in 48 counties within Iowa {Figure 1) and it is ...

Research On Nitrogen Indices In Wisconsin And The Midwest, Larry G. Bundy

Proceedings of the Integrated Crop Management Conference

Development of reliable nitrogen (N) availability indices has long been an important goal of agricultural scientists. However, progress in this area has been slowed by problems with calibrating certain N indices with crop response and by the absence of strong incentives to develop and implement N tests. Nitrogen test development for humid regions of the Midwest and eastern U.S. is more difficult due to climatic conditions in these areas which can cause relatively rapid changes in the amounts of plant-available N in the crop root zone.

Weed Aggressivity In Agronomic Crops, Edward E. Schweizer

Proceedings of the Integrated Crop Management Conference

The quantity of herbicides applied in crops has disturbed environmentalists for many years and several environmental groups have voiced distress about the impact of herbicides on water quality, the food supply, and human health. These concerns are causing administrators, scientists, and farmers to search for farming practices and research programs that can effectively balance agri chemical usage with the protection of national resources, food supplies, and human health (Anonymous, 1989a; Anonymous, 1989b). "Society will become more environmentally sensitive, and agricultural practices will become more environmentally friendly. Pesticides that cause unacceptable environmental damage or threaten health will be withdrawn. During the ...

Water And Risk Assessment, Vernon N. Houk

Proceedings of the Integrated Crop Management Conference

Thank you for giving me the opportunity to speak to you today about carcinogens in drinking water and water quality standards. In this emotion-filled, media-hyped, chemo-phobic society in which we live, the more we spend to comply with regulations that supposedly reduce the risk of cancer, the less safe the American public seems to feel.

Woolly Cupgrass Biology And Management, Michael D. K. Owen

Proceedings of the Integrated Crop Management Conference

Woolly cupgrass (Eriochloa villosa [Thumb.] Kunth.) is a relatively new weed in Iowa. Woolly cupgrass is native to East Asia, specifically China and Korea, and was first reported in the United States during the 1940's. The first identified infestation in Iowa was located in Ringgold County and reported in 1957. Since then, economically important infestations have been discovered throughout Iowa, Illinois, Minnesota, and Wisconsin. Recent estimates suggest that woolly cupgrass infests approximately 7 to 10% of the row crop acres in Iowa. While this weed can be found in most areas of Iowa, localized and severe infestations occur in ...

Herbicide Resistance In Crops And Weeds, Michael D. K. Owen

Proceedings of the Integrated Crop Management Conference

Herbicide resistance, whether as a potential problem in weeds, or as a potentially important agronomic tool, has become an extremely volatile issue in agriculture. Documents such as Biotechnology's Bitter Harvest suggest that herbicide resistance in crops will be a major environmental and economic disaster. Industry representatives suggest that herbicide resistant crops will be excellent tools for growers and actually improve the environmental safety of herbicide use. Agronomists voice concerns about the appearance of weed biotypes that demonstrate herbicide resistance. This paper will provide an objective review of herbicide resistance in crops and weeds and suggest possible results of herbicide ...

Immunoassays For Pesticide Detection, Robert G. Hartzler

Proceedings of the Integrated Crop Management Conference

The occurrence of herbicides and other agricultural chemicals in groundwater continues to be a major concern in Iowa and across the country. Analytical capabilities have improved dramatically in the past twenty years, resulting in the ability to detect ever smaller quantities of chemicals (the vanishing zero). Detection of pesticides has been based primarily on conventional technology, such as gas or high-performance-liquid chromatographic methods. Although these methods are highly sensitive, they are also very expensive and time consuming. Immunoassay tests are alternative analytical methods that are also highly sensitive, but can be used by persons with little or no scientific background ...

The Potential Role Of Cover Crops In Iowa Cropping Systems, Robert G. Hartzler

Proceedings of the Integrated Crop Management Conference

Cover crops play an important role in crop management systems in many parts of the country; however, there has been little use of this practice in Iowa in recent years. Increasing concerns over the impacts of agriculture on the environment has caused a renewed interest in the potential role of cover crops. This paper will discuss potential benefits and risks of cover crops, and also discuss some of the systems currently being investigated.

Control Of Corn Leaf Diseases, C. A. Martinson

Proceedings of the Integrated Crop Management Conference

Leaf diseases of corn in Iowa in 1990 were probably the most severe since the 1970 epidemic of Southern corn leaf blight. The leaf diseases resulted in an "early maturing" of the corn in many fields which was attributed erroneously to a late season heat stress in many popular reports. These leaf diseases combined with heavy corn borer infestations in some areas contributed greatly to the smaller kernels, poor kernel fill, and lower yields than expected. The leaf diseases will be discussed individually.