Hemorrhagic disease in Kansas: enzootic stability meets epizootic disease

Kansas (USA) could represent a transition area between contrasting epidemiologic patterns of hemorrhagic disease (HD) in the midwestern United States. In this study, we compare the distribution of reported clinical HD with serologic data to determine whether the risk of HD in white-tailed deer (Odocoileus virginianus) is associated with geographic location corresponding to the reported distribution of two white-tailed deer subspecies. On the basis of a high prevalence of antibodies (91-100%) to multiple serotypes of epizootic hemorrhagic disease virus (EHDV) and bluetongue virus (BTV), with correspondingly few reports of clinical HD, it appears that a state of enzootic stability exists in central and western Kansas. This area corresponds to the reported range of O. virginianus texanus. In contrast, in the eastern third of the state, which corresponds to the reported range of O. virginianus macronurus, antibody prevalence is significantly lower (45%), EHDV serotypes appear to predominate, and HD, as confirmed by virus isolation, has been consistently reported. These results suggest an abrupt demarcation between enzootic stability in central and western Kansas to a pattern of epizootic HD within the eastern part of this state. Understanding host, vector, and environmental variables responsible for these contrasting patterns could have application to understanding the risk of HD in the midwestern United States.     

Plastids and stromules interact with the nucleus and cell membrane in vascular plants

The various metabolic activities of plastids require continuous exchange of reactants and products with other organelles of the plant cell. Physical interactions between plastids and other organelles might therefore enhance the efficiency of plant metabolism. We have observed a close apposition of plastids and nuclei in various organs of Nicotiana tabacum and Arabidopsis thaliana. In hypocotyl epidermal cells, plastids and stromules, stroma-filled tubular extensions of the plastid envelope membrane, were observed to reside in grooves and infoldings of the nuclear envelope, indicating a high level of contact between the two organelle membranes. In a number of non-green tissues, including suspension-cultured cells, perinuclear plastids were frequently associated with long stromules that extended from the cell center to the cell membrane. In cotyledon petioles, cells lying adjacent to one another frequently contained stromules that met on either side of the shared cell wall, suggesting a means of intercellular communication. Our results therefore suggest that stromules have diverse roles within plant cells, perhaps serving as pathways between nuclei and more distant regions of the cell and possibly even other cells.     

The structure of the neurotoxin-associated protein HA33/A from Clostridium botulinum suggests a reoccurring beta-trefoil fold in the progenitor toxin complex

The hemagglutinating protein HA33 from Clostridium botulinum is associated with the large botulinum neurotoxin secreted complexes and is critical in toxin protection, internalization, and possibly activation. We report the crystal structure of serotype A HA33 (HA33/A) at 1.5 A resolution that contains a unique domain organization and a carbohydrate recognition site. In addition, sequence alignments of the other toxin complex components, including the neurotoxin BoNT/A, hemagglutinating protein HA17/A, and non-toxic non-hemagglutinating protein NTNHA/A, suggests that most of the toxin complex consists of a reoccurring beta-trefoil fold.     

Strain distribution of alfalfa weevil (Coleoptera: Curculionidae) in an intergrade zone

Strain distribution for the alfalfa weevil, Hypera postica (Gyllenhal), was determined for the five major alfalfa-growing regions of New Mexico. Mitochondrial DNA from field-collected weevils at each location was digested and sequenced to differentiate among strains. Eastern, Egyptian, and western strains were recovered, along with a population not matching any known strain. The majority of sites examined had populations of two strains intermingled within a field. This is the first confirmation of the presence of all three strains within the same geographic region. Possible implications for alfalfa weevil management are discussed.     

Preferential cell death of CD8+ effector memory (CCR7-CD45RA-) T cells by hydrogen peroxide-induced oxidative stress

T cells are used in many cell-based cancer treatments. However, oxidative stress that is induced during various chronic inflammatory conditions, such as cancer, can impair the immune system and have detrimental effects on T cell function. In this study, we have investigated the sensitivity of different human T cell subsets to H(2)O(2)-induced oxidative stress. We showed that central memory (CD45RA(-)CCR7(+)) and effector memory (CD45RA(-)CCR7(-)) T cells are more sensitive to H(2)O(2) as compared with naive (CD45RA(+)CCR7(+)) T cells. Furthermore, the study showed that CD8(+) effector memory T cells are more sensitive to low levels of H(2)O(2) (5 microM) compared with other types of T cells investigated. H(2)O(2)-exposed CD45RO(+) T cells showed mitochondrial depolarization prior to caspase 3 activity. Moreover, the pan-caspase inhibitor z-Val-Ala-Asp(OMe)-fluoromethylketone rescued cells from death. These experiments suggest that H(2)O(2)-induced cell death of CD45RO(+) T cells acts via the mitochondrial pathway and that caspase involvement is needed. This study suggests that oxidative stress in cancer patients can be disadvantageous for T cell-based adoptive cell transfer therapies, since effector memory T cells are the primary phenotype of the cells administered.     

Vasodilator tone in the llama fetus: the role of nitric oxide during normoxemia and hypoxemia

The fetal llama responds to hypoxemia, with a marked peripheral vasoconstriction but, unlike the sheep, with little or no increase in cerebral blood flow. We tested the hypothesis that the role of nitric oxide (NO) may be increased during hypoxemia in this species, to counterbalance a strong vasoconstrictor effect. Ten fetal llamas were operated under general anesthesia. Mean arterial pressure (MAP), heart rate, cardiac output, total vascular resistance, blood flows, and vascular resistances in cerebral, carotid and femoral vascular beds were determined. Two groups were studied, one with nitric oxide synthase (NOS) blocker N(G)-nitro-L-arginine methyl ester (L-NAME), and the other with 0.9% NaCl (control group), during normoxemia, hypoxemia, and recovery. During normoxemia, L-NAME produced an increase in fetal MAP and a rapid bradycardia. Cerebral, carotid, and femoral vascular resistance increased and blood flow decreased to carotid and femoral beds, while cerebral blood flow did not change significantly. However, during hypoxemia cerebral and carotid vascular resistance fell by 44% from its value in normoxemia after L-NAME, although femoral vascular resistance progressively increased and remained high during recovery. We conclude that in the llama fetus: 1) NO has an important role in maintaining a vasodilator tone during both normoxemia and hypoxemia in cerebral and femoral vascular beds and 2) during hypoxemia, NOS blockade unmasked the action of other vasodilator agents that contribute, with nitric oxide, to preserving blood flow and oxygen delivery to the tissues.     

Uncoupling of respiration-linked contraction in corn mitochondria

Respiration-linked contraction of corn mitochondria is not noticeably reduced by low, uncoupling concentrations of dinitrophenol. However, if a contraction/respiration ratio is calculated, the contraction proves to be uncoupled. Previous statements that contraction cannot be uncoupled from respiration are in error.

The uncoupling of contraction is consistent with the concept that dinitrophenol attacks a primary non-phosphorylated high energy intermediate (I~X). It is proposed that this intermediate is linked to some contractile mechanism such that the degree of contraction reflects the level of intermediate.

     

Immunochemical studies with soluble and mitochondrial pyruvate carboxylase activities from rat tissues

1. Pyruvate carboxylase (EC 6.4.1.1), purified from rat liver mitochondria to a specific activity of 14 units/mg, was used for the preparation of antibodies in rabbits. 2. Tissue distribution studies showed that pyruvate carboxylase was present in all rat tissues that were tested, with considerable activities both in gluconeogenic tissues such as liver and kidney and in tissues with high rates of lipogenesis such as white adipose tissue, brown adipose tissue, adrenal gland and lactating mammary gland. 3. Immunochemical titration experiments with the specific antibodies showed no differences between the inactivation of pyruvate carboxylase from mitochondrial or soluble fractions of liver, kidney, mammary gland, brown adipose tissue or white adipose tissue. 4. The antibodies were relatively less effective in reactions against pyruvate carboxylase from sheep liver than against the enzyme from rat tissues. 5. Pyruvate carboxylase antibodies did not inactivate either propionyl-CoA carboxylase or acetyl-CoA carboxylase from rat liver. 6. It is concluded that pyruvate carboxylase in lipogenic tissues is similar antigenically to the enzyme in gluconeogenic tissues and that the soluble activities of pyruvate carboxylase detected in many rat tissues do not represent discrete enzymes but are the result of mitochondrial damage during tissue homogenization.     

The effect of reduced water potential on soybean mitochondria

The respiration of excised hypocotyls and of isolated hypocotyl mitochondria from soybean [Glycine max (L.) Merr., var. Wayne] was determined in various concentrations of sucrose and potassium chloride. Hypocotyl oxygen uptake declined with increasing solute concentration; no specific effects of either solute were apparent. Mitochondrial state III respiration was strongly inhibited as the solute concentrations were raised and there was in addition a specific inhibitory effect of the salt. State IV respiration, however, was unaffected by the presence of osmoticum. ADP/O ratios were also unaffected, except at high potassium chloride concentrations (470 mm). The primary effect of solutes was thus to limit the rate of substrate oxidation.