Viruses and the cellular RNA decay machinery.

The ability to control cellular and viral gene expression, either globally or selectively, is central to a successful viral infection, and it is also crucial for the host to respond and eradicate pathogens. In eukaryotes, regulation of message stability contributes significantly to the control of gene expression and plays a prominent role in the normal physiology of a cell as well as in its response to environmental and pathogenic stresses. Not surprisingly, emerging evidence indicates that there are significant interactions between the eukaryotic RNA turnover machinery and a wide variety of viruses. Interestingly, in many cases viruses have evolved mechanisms not only to evade eradication by these pathways, but also to manipulate them for enhanced viral replication and gene expression. Given our incomplete understanding of how many of these pathways are normally regulated, viruses should be powerful tools to help deconstruct the complex networks and events governing eukaryotic RNA stability

Effects of arginine and ornithine supplementation to a high‐protein diet on selected cellular immune variables in adult cats

Background: Dietary protein and amino acid intake and composition can modulate immune function. Objectives: To evaluate the effects of high‐protein intake and arginine and ornithine supplementation on feline immune cells. Animals: Ten healthy cats. Methods: Experimental study. Cats received a high‐protein basal diet as a single daily meal. A crossover design was applied with treatments being basal diet (w/o); basal diet with arginine supplementation (+50, 75, 100% compared to the arginine provision by the basal diet; Arg 1‐3); and basal diet with ornithine supplementation (+100, 150, 200% compared to the arginine provision by the basal diet; Orn 1‐3). Blood samples were collected at the end of each 11‐day treatment period. Results: Mitogen‐stimulated proliferative activity of blood leukocytes revealed a quadratic effect for the dietary supplementation of arginine (P = .02) and ornithine (P = .03) (means for ConA‐stimulation: w/o = 6.96; Arg 1 = 9.31; Arg 2 = 11.4; Arg 3 = 8.04; Orn 1 = 15.4; Orn 2 = 9.43; Orn 3 = 9.28; pooled SEM: 0.96). The number (% gated) of phagocytic granulocytes linearly decreased with increasing dietary concentrations of arginine (P = .05) and ornithine (P = .03) (means: w/o = 95.5; Arg 1 = 93.0; Arg 2 = 92.5; Arg 3 = 92.6; Orn 1 = 92.6; Orn 2 = 92.6; Orn 3 = 91.5; pooled SEM = 0.44). Conclusions and Clinical Importance: This study could demonstrate immunomodulating properties of dietary arginine and ornithine in cats

Expression of interleukin 2 receptors on activated human B cells.

Using anti-Tac, a monoclonal anti-interleukin 2 (IL-2) receptor antibody, we have explored the possibility that certain activated B cells display receptors for IL-2. Resting normal B cells and unselected B cell lines established from normal individuals were Tac antigen negative. In contrast, the cell surface Tac antigen expression was demonstrable on 6 of 10 B cell lines from patients with Burkitt's lymphoma, 5 of 6 B cell lines derived from patients with HTLV-I-associated adult T cell leukemia (including all four that had integrated HTLV-I into their genome), and on certain normal B cells activated with pokeweed mitogen. Furthermore, cloned Epstein-Barr virus-transformed B cell lines derived from Tac-positive normal B cells continued to express the Tac antigen in long-term cultures and manifested high affinity IL-2 receptors identified in binding studies with purified radiolabeled IL-2. The line 5B4 developed in the present study could be induced with purified JURKAT-derived or recombinant IL-2 to express a larger number of IL-2 receptors. Furthermore, the addition of IL-2 to the 5B4 B cell line augmented IgM synthesis, which could be blocked by the addition of anti-Tac. The size of the IL-2 receptors expressed on the cloned normal B cell lines was similar (53,000-57,000 daltons) to that of receptors on phytohemagglutinin-stimulated T cell lymphoblasts. Thus, certain malignant and activated normal B cells display the Tac antigen and manifest high affinity receptors for IL-2. These data suggest that IL-2 may play a role in the differentiation of activated B cells into immunoglobulin-synthesizing and -secreting cells

Vitamin E requirements of adult domestic cats (Felis catus) fed diets containing high levels of fish oil : a thesis presented in partial fulfilment of the requirement for the degree of Master of Nutritional Sciences at Massey University, Palmerston North, New Zealand

The vitamin E (α-tocopherol) requirement of adult cats fed diets containing high levels of fish oil was investigated. Thirty-two (16 male, 16 female) adult domestic cats (Felis catus) were randomly allocated to four groups according to sex and fed one of four experimental diets (A, B, C, and D) for 126 days. The cats were housed in large outdoor pens in groups of 8 cats. Diets A, B, C and D contained approximately 300 g of fish oil per kg diet dry matter and were supplemented to contain 0, 5, 10, and 15 IU DL-α-tocopheryl acetate per g added fish oil per kg diet, respectively. The diets were provided ad libitum with water being available at all times. Food intake was measured daily and body weights were measured at weekly intervals. Blood samples were taken from the jugular vein of each cat at bi-weekly intervals during the study. Blood samples were analysed for plasma α-tocopherol, red blood cell H₂O₂ (4 and 2 %) haemolysis, the ferric reducing ability of plasma, plasma lipid peroxides, plasma triglycerides, alkaline phosphatase and whole blood lymphocyte proliferation. All cats remained healthy throughout the study except one female cat who was removed after 3 weeks due to poor food intake. The four diets were analysed and found to be free of peroxides. The average daily metabolisable energy intake of the cats on diet A, B, C and D at the end of study were similar and were 289, 261, 256, and 267 kJ·kg⁻¹ body weight, respectively. No clinical signs of vitamin E deficiency were observed in any of the cats. The plasma α-tocopherol concentrations of the cats in the four groups at the start of the study were not significantly different between the four groups (mean ± SEM, 3.4 ± 0.2 μg-ml⁻¹). When the cats were fed diet A (unsupplemented), the mean plasma α-tocopherol concentration remained relatively low and the RBC 4 % H₂O₂ haemolysis remained high, while the RBC 2 % H₂O₂ haemolysis decreased consistently. Plasma lipid peroxides remained relatively low throughout the study. The ferric reducing ability of plasma status was compromised in the cats on the unsupplemented diet. There was no significant (P < 0.05) difference in any of the response parameters measured amongst the cats fed diets B, C and D except for the RBC 4 % H₂O₂ haemolysis of the cats on diet B which was significantly higher than those on diet C and D at week 4 and week 8, and the LPO value of the cats on diet D which was significantly higher than those of the cats on diet B and C at week 4. The vitamin E requirement of adult cats fed a high level of fish oil, using the response parameters measured, was estimated to be between 0 and 5 IU of vitamin E per g added fish oil per kg diet. The current recommendation of the Association of American Feed Control Officials (10 IU vitamin E/g fish oil/kg diet) appears to be well in excess. The results from the present study also showed that there was no beneficial effect of dietary vitamin E on whole blood cell proliferation when vitamin E levels were 150 % of the recommendations of the Association of American Feed Control Officials. The vitamin E requirement of adult cats to optimise immune response warrants further investigation

NEMATICIDAL ACTIVITY OF EXTRACTS FROM \u3ci\u3ePHYTOLACCA AMERICANA \u3c/i\u3e ON FIVE PLANT-PATHOGENIC NEMATODE SPECIES OF ECONOMIC IMPORTANCE

Plant-parasitic nematodes cause significant losses to plant agriculture annually. The limited availability and high cost of synthetic nematicides, along with the environmental risks associated with their use, have created a renewed interest in the search for alternative management tactics. One such alternative tactic is the use of plant extracts. The focus of this research is the evaluation of the nematicidal activity of water extracts from Pokeweed (Phytolacca americana). In vitro and greenhouse tests were performed to evaluate the effects of the extracts on five species of plant-pathogenic nematodes of economic importance: Aphelenchoides fragariae, Ditylenchus dispsaci, Meloidogyne incognita, Pratylenchus penetrans, and Rotylenchulus reniformis. Chapter 1 describes an in vitro method for screening of compounds in aqueous suspensions, using small volumes. The results show differential susceptibility of three species of nematodes to oxamyl, the carbamate nematicide used as positive control. The mode of action of oxamyl is through the inhibition of acetylcholinesterase (AChE). The marked differences in the inhibition potency of oxamyl on AChE of D. dipsaci, P. penetrans and A. fragariae are discussed. Chapter 2 reports the results of screening for nematicidal activity of extracts from six plants: Aloe barbadensis (aloe), Ilex opaca (American holly), Nerium oleander (oleander), Phytolacca Americana (pokeweed), Pueraria montana (kudzu), and Quercus shumardii (red oak). Different plant parts and two extraction methods were evaluated for each plant species on three nematode species. Results showed that extracts from pokeweed leaves were the only ones with consistently high activity against the three nematode species. Additionally, different solvents were evaluated for extraction of compounds from pokeweed leaves, including acetone, ethanol, and methanol. Chapter 3 evaluates water extracts from pokeweed leaves in the greenhouse for activity against R. reniformis and M. incognita on soybean plants. Greenhouse results show the extracts are a promising alternative for management of M. incognita. Extracts were analyzed by chromatography for identification of prominent compounds with reported activity against other microorganisms. Two of the compounds identified, astragalin and chlorogenic acid, were evaluated in vitro individually, but did not show nematicidal activity at the concentrations present in the extracts. Based on in vitro and greenhouse assays, we conclude that pokeweed leaf extracts show nematicidal activity that could be incorporated in an integrated pest management plan for several plant-pathogenic nematode species

Monoclonal antibodies reactive with swine lymphocytes

A panel of monoclonal antibodies (mAb) with specificity for swine leukocytes was prepared by somatic cell hybridization with the use of spleen cells from mice immunized with swine thymocytes. The reactivity of two mAb (295/33 and 122/28), which both immunoprecipitated from the surface of swine leukocytes an antigen termed S-L2 with an apparent m.w. of 33 to 35 kilodaltons under reducing and 65 to 70 kilodaltons under nonreducing conditions, was investigated in detail. These mAb were reactive in indirect immunofluorescence with 50 to 60% of thymocytes, 35% of peripheral blood lymphocytes, and 55% of E rosette- positive cells; they were nonreactive with bone marrow cells, Ig+ B cells, nonrosetting lymphocytes, granulocytes, and monocytes. In functional studies, the elimination of S-L2+ cells partially reduced the proliferative response to concanavalin A and pokeweed mitogen but not to Staphylococcus aureus and lipopolysaccharide. The S-L2- subset proliferated well to alloantigens. Both cytolytic T effector cells and precursor cells carried the antigen S-L2 and could be depleted from heterogeneous cell populations by both antibodies in the presence of complement. These data suggest that the mAb 295/33 and 122/28 recognize a specific polypeptide present on the surface of swine cytolytic T cells. These antibodies will be useful in studies on the swine immune system

Ovipositional preference, fidelity, and fitness of \u3ci\u3eDrosophila suzukii\u3c/i\u3e in a co-occurring crop and non-crop host system

Drosophila suzukii (Matsumura) is a devastating pest of soft-skinned fruits including blackberries and raspberries. Management of this pest is focused on preventing infestation in crops, but non-crop hosts may play an important role in enabling D. suzukii to persist in the absence of cultivated hosts. Drosophila suzukii may also infest fruits of both crop and non-crop hosts concurrently. Our goals were to determine whether (1) D. suzukii prefers to oviposit in cultivated blackberry, Rubus L. subgenus rubus Watson, or American pokeweed, Phytolacca americana, a non-crop host commonly found along field edges, (2) D. suzukii prefers to oviposit into the same host from which it emerged, and (3) performance differs between D. suzukii progeny that develop in blackberries or pokeweed berries. Although the pest was able to infest both hosts at the same rate, we found that D. suzukii females emerging from pokeweed preferred to oviposit into blackberries, while females emerging from blackberry had no preference. Progeny that developed in blackberries were more fit than progeny that developed in pokeweed berries based on several measures. In field locations, cultivated blackberries and pokeweed berries only overlapped in availability for a short period of time, and infestation rates were variable between blackberries and pokeweed berries collected during that period. Nonetheless, these results suggest that noncrop hosts may facilitate the invasion of D. suzukii and perpetuate infestation of cultivated hosts under certain circumstances

Potyviral Genome-Linked Protein and its Interaction with Plant Defense Ribosome Inactivating Protein from Phytolacca Americana

Agriculture is an indispensable part of every person’s life, ensuring that nutritious and inexpensive food is readily available. Agriculture continues to be confronted with epidemics, having devastating effects on economies and the plant sources essential for human and animal life. Plants and their pathogens have developed evolutionary adaptations, each shaping the other’s defence and invasive strategies. Many different plants produce toxic ribosome inactivating proteins that aid in their defence mechanisms against pathogenic invaders. Viruses must adapt to the host translational machinery, several having evolved to include viral genome-linked proteins that carry numerous viral functions. Here, we review how a potyviral protein from turnip mosaic virus linked to its genome is able to inhibit pokeweed plant defence protein, and perhaps potentially conferring viral resistance to the toxin

Common Pokeweed Management in Corn and Soybeans with a Conservation Tillage Cultivator and Herbicides

Common pokeweed (Phytolacca americana L.) is a warm-season perennial that grows well in nondisturbed areas such as fence rows and woodland borders. In recent years it has begun spreading to com and soybean fields where no-tillage practices are used. The deep taproot that is characteristic of common pokeweed, makes this weed difficult to manage, particularly in no-till plantings. The green leaves, fleshy stems, and purple berries of common pokeweed can inhibit the harvesting process and lead to discounts at the elevator for high moisture and stained seed. The equipment industry has developed cultivators with large sweeps capable of operating in no-till plantings with minimal disturbance to stubble and plant residue at the soil surface. These cultivators are called conservation tillage cultivators and are intended to operate at shallow depths to cut plants below the soil surface. The fact that plants with deep taproots generally do not tolerate tillage may make the conservation tillage cultivator a valuable tool for managing common pokeweed in no-till plantings. The objective of this research was to evaluate the effectiveness of a conservation-till cultivator with and without herbicide treatments for common pokeweed control in corn and soybean

Extensive evolution of cereal ribosome-inactivating proteins translates into unique structural features, activation mechanisms, and physiological roles

Ribosome-inactivating proteins (RIPs) are a class of cytotoxic enzymes that can depurinate rRNAs thereby inhibiting protein translation. Although these proteins have also been detected in bacteria, fungi, and even some insects, they are especially prevalent in the plant kingdom. This review focuses on the RIPs from cereals. Studies on the taxonomical distribution and evolution of plant RIPs suggest that cereal RIPs have evolved at an enhanced rate giving rise to a large and heterogeneous RIP gene family. Furthermore, several cereal RIP genes are characterized by a unique domain architecture and the lack of a signal peptide. This advanced evolution of cereal RIPs translates into distinct structures, activation mechanisms, and physiological roles. Several cereal RIPs are characterized by activation mechanisms that include the proteolytic removal of internal peptides from the N-glycosidase domain, a feature not documented for non-cereal RIPs. Besides their role in defense against pathogenic fungi or herbivorous insects, cereal RIPs are also involved in endogenous functions such as adaptation to abiotic stress, storage, induction of senescence, and reprogramming of the translational machinery. The unique properties of cereal RIPs are discussed in this review paper