Evolutionary relationships among hares from North Africa (Lepus sp. or Lepus spp.), cape hares (L. capensis) from South Africa, and brown hares (L. europaeus), as inferred from mtDNA PCR-RFLP and allozyme data

Systematics and taxonomy of hares of the genus Lepus (Lagomorpha) are under contentious debate, and phylogenetic relationships among many taxa are not well understood. Here we study genetic differentiation and evolutionary relationships among North African hares, currently considered subspecies of Lepus capensis , cape hares ( L. capensis ) from the Cape province in South Africa, and brown hares ( L. europeaus ) from Europe and Anatolia, using maternally (mtDNA) and biparentally (allozymes) inherited markers. A polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of a c. 1.8 kb long segment of the mitochondrial control region using eight hexanucleotide-recognizing restriction endonucleases yielded 28 haplotypes, and horizontal starch gel electrophoresis of proteins encoded by 25 structural gene loci revealed 52 alleles at 18 polymorphic loci. Diverse phylogenetic analyses (neighbor joining dendrogram, median joining network, multidimensional scaling of pairwise distances, AMOVA, F -statistics, hierarchical F -statistics) of genetic variants revealed marked substructuring of mtDNA into three phylogeographic groups, namely an African, a central European, and an Anatolian, but a somewhat less pronounced overall differentiation of the nuclear genome, despite a relatively high number of population-specific (private) alleles. However, all our results are not incongruent with Petter's (1959: Mammalia 23 , 41; 1961: Z. f. Säugetierkunde 26 , 30; 1972 : Société Des Sciences Naturelles et Physiques du Maroc 52 , 122) hypothesis that North African hares generally belong to L. capensis and that brown hares should be included in this species as well.     

Significance of Polyamines for Flowering in Spirodela punctata

Spirodela punctata strain O 5, a quantitative long-day plant,flowers only when ethylene-diamine-di-o-hydroxyphenylaceticacid (EDDHA) or salicylic acid was added to the nutrient medium[Scharfetter et al. (1978) Z. Pflanzenphysiol. 87: 445]. Undersuch conditions, cyclohexylamine and methylglyoxal-bis(guanylhydrazone)(both blockers of polyamine synthesis) inhibited flowering withoutsignificant effects on vegetative growth. Supply of spermidineabolished completely the inhibitor effects, but cannot replacethe EDDHA effect on flowering. ¹Dedicated to Prof. O. H. Volk, Wurzburg, on his 85th birthday. ²Present address: Facultad de Ciencias Forestales, UniversidadAutónoma de Nuevo León. Ap. Post. 41, 67700 Linares,Nuevo León, México. (Received October 19, 1988; Accepted February 3, 1989)     

Influence of maize root mucilage on soil aggregate stability

This study was undertaken to determine the effects of root exudates on soil aggregate stability. Root mucilage was collected from two-month old maize plants (Zea mays L.) Mucilage and glucose solutions were added at a rate of 2.45 g C kg⁻¹ dry soil to silty clay and silt loam soils. Amended soils, placed in serum flasks, were incubated for 42 d with a drying-wetting cycle after 21 d. Evolved CO₂ was measured periodically as well as the water-stable aggregates and soluble sugar and polysaccharide content of the soil. In mucilage-amended soils CO₂ evolution started with a lag phase of 2–3 days, which was not observed in glucose-amended soils. There was then a sharp increase in evolved CO₂ up to day 7. During the second incubation period there were only small differences in evolved C between treatments. Incorporation of mucilage in both soils resulted in a spectacular and immediate increase in soil aggregate stability. Thereafter, the percent of water-stable aggregates quickly decreased parallel to microbial degradation. On completion of the incubation, aggregate stability in the silty clay soil was still significantly higher in the presence of mucilage than in the control. This work supports the assumption that freshly released mucilage is able to stick very rapidly to soil particles and may protect the newly formed aggregates against water destruction. On the silty clay, microbial activity contributes to a stabilization of these established organo-mineral bounds.     

Cytopathology and Ultrastructure of Some African Isolates of Maize Streak and Sugarcane Streak Viruses

Samples of maize leaves naturally infected with maize streak virus (MSV) from Malawi and South Africa, as well as sugarcane leaves naturally infected with sugarcane streak virus (SSV) from Egypt, were examined by light (LM) and transmission electron, microscopy (TEM). Intranuclear inclusions, detectable by both methods, were found mainly in mesophyll and bundle sheath cells, and less frequently in vascular parenchyma and immature phloem cells. At higher TEM magnifications, these inclusions consisted, of crystalline or noncrystalline aggregates of isometric geminivirus–like particles (VLP) that occurred either singly or in geminate arrays. Cytopathological changes in these cells were confined to the nuclei, which were usually larger than normal, with peripheral chromatin and nucleoli. The nuclear envelope of some inclusion–containing nuclei was ruptured, and occasionally a crystal of VLP was found in the cytoplasm of cells in which no intact nuclei were detected. No differences in cytopathology were found between MSV and SSV, or between the two MSV isolates examined.     

Modulation of fibroblast response to maitotoxin along the cell division cycle

Maitotoxin (MTX) induces an increase of [Ca²⁺]_i and of phosphoinositide breakdown in various cell types. The [Ca²⁺]_i increase followed with fluorescent probes on cell suspensions has been described as slow and lasting, in contrast to the signal induced by calcium ionophores such as ionomycin. MTX effects have been studied on two fibroblastic cell lines, BHK21 C13 and FR 3T3, synchronized by serum deprivation treatment performed in an isoleucine-free medium for BHK21 C13 cells. In BHK21 C13 cells, flow cytometry analysis showed that two stages, G1/S and G2/M, were particularly susceptible to MTX treatment. Scanning laser cytometry demonstrated that calcium response of FR 3T3 fibroblasts followed with Indo-1 varied during the cell division cycle. The [Ca²⁺]_i increase was almost always vertical, but its delay after MTX addition lasted from zero (S and G2/M transition) to 10–20 min (G1) or more (G2). No [Ca²⁺]_i change could be detected during mitosis. The [Ca²⁺]_i response at the S phase was biphasic. These observations suggest that (1) the lasting response described in the literature represents a global cell population effect, and (2) cells are more sensitive to MTX at specific stages of the cell division cycle, which could correspond to periods when calcium signals have been detected in different cell types.Abbreviations MTX maitotoxin - [Ca²⁺]_i intracellular calcium concentration - IP₃ inositol triphosphate     

Survival and growth of Escherichia coli O157:H7 in ground, roasted beef as affected by pH, acidulants, and temperature.

A study was undertaken to determine the fate of Escherichia coli O157:H7 in ground, roasted beef as influenced by the combined effects of pH, acidulants, temperature, and time. There was essentially no change in the viable population of E. coli O157:H7 when beef salads (pH 5.40 to 6.07) containing up to 40% mayonnaise were incubated at 5 degrees C for up to 72 h. At 21 and 30 degrees C, significant (P < or = 0.05) increases in populations of the organism occurred in salads containing 16 to 32% mayonnaise (pH 5.94 to 5.55) between 10 and 24 h of incubation. Death was more rapid as the pH of acidified beef slurries incubated at 5 degrees C was decreased from 5.98 to 4.70. E. coli O157:H7 grew in control slurries (pH 5.98) and in slurries containing citric and lactic acids (pHs 5.00 and 5.40) incubated at 21 degrees C for 24 h; decreases occurred in slurries acidified to pHs 4.70, 5.00, and 5.40 with acetic acid or pH 4.70 with citric or lactic acid. At 30 degrees C, populations decreased in slurries acidified to pHs 4.70 and 5.00 with acetic acid. Citric and lactic acids failed to prevent significant increases in populations in slurries at pH 4.70 to 5.40 between 10 and 24 h of incubation. The order of effectiveness of acidulants in inhibiting growth was acetic acid > lactic acid > or = citric acid. The same order was observed for inactivation of E. coli O157:H7 in acidified (pH 5.00) beef slurry heated at 54 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)     

Brain Insulin Dysregulation: Implication for Neurological and Neuropsychiatric Disorders

Arduous efforts have been made in the last three decades to elucidate the role of insulin in the brain. A growing number of evidences show that insulin is involved in several physiological function of the brain such as food intake and weight control, reproduction, learning and memory, neuromodulation and neuroprotection. In addition, it is now clear that insulin and insulin disturbances particularly diabetes mellitus may contribute or in some cases play the main role in development and progression of neurodegenerative and neuropsychiatric disorders. Focusing on the molecular mechanisms, this review summarizes the recent findings on the involvement of insulin dysfunction in neurological disorders like Alzheimer’s disease, Parkinson’s disease and Huntington’s disease and also mental disorders like depression and psychosis sharing features of neuroinflammation and neurodegeneration.     

Serum haptoglobins in experimental coccidioidomycosis — A preliminary report

Summary The level of haptoglobin was determined in control rats and in rats infected withC. immitis. The haptoglobin levels in the infected group were significantly higher than in those in the control group. The possibility that serial determinations may be of value in following the course of this disease is currently being investigated.This study was supported in part by USPHS Grants A1-06048-01, 5 T1 A1 52–06 and the Dermatologic Research Foundation of California, Inc.     

Monitoring tropical forests under a functional perspective with satellite‐based vegetation optical depth

Monitoring ecosystem functions in forests is a priority in a climate change scenario, as climate‐induced events may initially alter the functions more than slow‐changing attributes, such as biomass. The ecosystem functional properties (EFPs) are quantities that characterize key ecosystem processes. They can be derived by point observations of gas and energy exchanges between the ecosystems and the atmosphere that are collected globally at FLUXNET flux tower sites and upscaled at ecosystem level. The properties here considered describe the ability of ecosystems to optimize the use of resources for carbon uptake. They represent functional forest information, are dependent on environmental drivers, linked to leaf traits and forest structure, and influenced by climate change effects. The ability of vegetation optical depth (VOD) to provide forest functional information is investigated using 2011–2014 satellite data collected by the Soil Moisture and Ocean Salinity mission and using the EFPs as reference dataset. Tropical forests in Africa and South America were analyzed, also according to ecological homogeneous units. VOD jointly with water deficit information explained 93% and 87% of the yearly variability in both flux upscaled maximum gross primary productivity and light use efficiency functional properties, in Africa and South America forests respectively. Maps of the retrieved properties evidenced changes in forest functional responses linked to anomalous climate‐induced events during the study period. The findings indicate that VOD can support the flux upscaling process in the tropical range, affected by high uncertainty, and the detection of forest anomalous functional responses. Preliminary temporal analysis of VOD and EFP signals showed fine‐grained variability in periodicity, in signal dephasing, and in the strength of the relationships. In selected drier forest types, these satellite data could also support the monitoring of functional dynamics.