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Archaeal Solute Could Be Next New and Improved Protein Stabilizer

Santos.

As shown most dramatically by the Taq polymerase enzyme that made PCR possible, compounds from hyperthermophilic organisms can have considerable commercial application. Researchers working with the marine archaeon Archaeoglobus fulgidus have identified a unique solute—diglycerol phosphate (DGP)—that exerts a strong protective effect against heat inactivation of proteins.

Helena Santos of the Universidade Nova de Lisbon in Oeiras, Portugal, and colleagues determined that DGP "is considerably better than glycerol as a thermoprotectant," at least for the proteins they tested. DGP conferred protection at a much lower concentration than mesophile-derived glycerol, one of the most commonly used stabilizing agents. DGP could help stabilize a number of biological products challenged by stressors such as high heat or freeze-drying. "It is likely to be useful [in stabilizing] enzymes used in diagnostic or analytical kits during operation as well as transport," Santos predicts.

(P. Lamosa, A. Burke, R. Peist, R. Huber, M.-Y. Liu, G. Silva, C. Rodrigues-Pousada, J. LeGall, C. Maycock, and H. Santos. 2000. Thermostabilization of proteins by diglycerol phosphate, a new compatible solute from the hyperthermophile Archaeoglobus fulgidus. Appl. Environ. Microbiol. 66:1974–1979.) Abstract | Full Text

Researchers Isolate Borna Disease Virus from Human Brain

Ikuta.

Kazuyoshi Ikuta of Osaka University, Japan, and colleagues offer new evidence to support the connection between the Borna disease virus (BDV) and schizophrenia. The research team isolated BDV for the first time from the brain of an autopsied schizophrenic patient.

The researchers were able to infect newborn Mongolian gerbils and retrieve human-derived BDV from their brains, pointing to a potentially effective approach for isolating BDV in cases of suspected human infection. The onset of the patient’s disease occurred shortly before death, which Ikuta acknowledges may have facilitated virus isolation.

The findings indicate that BDV can establish a persistent, productive infection in the human brain, Ikuta says. However, this report concerns a single patient case study, "and does not allow conclusions regarding the significance of BDV infection in humans," he cautions.

(Y. Nakamura, H. Takahashi, Y. Shoya, T. Nakaya, M. Watanabe, K. Tomonaga, K. Iwahashi, K. Ameno, N. Momiyama, H. Taniyama, T. Sata, T. Kurata, J. C. de la Torre, and K. Ikuta. 2000. Isolation of Borna disease virus from human brain tissue. J. Virol. 74:4601–4611.) Abstract | Full Text

Whitefly Mating Contributes to Plant Virus Spread

Czosnek and Ghanim

Insect sex appears to contribute to the transmission of tomato yellow leaf curl virus (TYLCV). In the first study to show that a plant virus can be sexually transmitted, Murad Ghanim and Henryk Czosnek of The Hebrew University of Jerusalem in Rehovot, Israel, found that uninfected flies became infected with TYLCV in the absence of any viral source other than infected partners.

"Transmission occurs probably via the insect body fluid, possibly by exchange or contamination of hemolymph during intercourse (quite similar to HIV)," Czosnek explains. The newly infected flies could then spread the virus to other insects and plants on which they fed.

However, the major route of TYLCV acquisition remains feeding on infected plants, Czosnek says. Sexual transmission may play a significant role in viral spread only when it occurs between insects on virus non-host plants such as cotton, he says.

(M. Ghanim and H. Czosnek. 2000. Tomato yellow leaf curl geminivirus (TYLCV-Is) is transmitted among whiteflies Bernisia tabaci) in a sex-related manner. J. Virol. 74:4738–4745.) Abstract | Full Text

Immunological Effects Typical of Induced Lupus in Silicone-Treated Mice

For several years, John Naim of Rochester General Hospital in Rochester, N.Y., and his colleagues have been building evidence that exposure to the silicone in breast implants can incite a chronic inflammation that disrupts immune regulatory pathways, but does not lead to classic autoimmunity. His lab’s latest research indicates that silicone oils and gels can induce hypergammaglobulinemia and stimulate macrophage activity.

Female A.SW mice treated with silicone produced notably elevated levels of immunoglobulin M (IgM), IgG3, and IgG1 as well as interleukin-6 (IL-6) and IL-1b , all abnormalities typical of lupus induced by pristane, the researchers note. However, none of the mice produced the autoantibodies normally associated with pristane-induced lupus. "Chronic immune stimulation by silicone gels and oils may lead to the production of a subset of autoantibodies, although not the full spectrum seen in pristane-treated mice," the researchers surmise.

(J. O. Naim, M. Satoh, N. A. Buehner, K. M. L. Ippolito, H. Yoshida, D. Nusz, L. Kurtelawicz, S. F. Cramer, and W. H. Reeves. 2000. Induction of hypergammaglobulinemia and macrophage activation by silicone gels and oils in female A.SW mice. Clin. Diagn. Lab. Immunol. 7:366–370.) Abstract | Full Text

Researchers Make Case for Canine Cryptosporidium Species

When is a genotype simply a genotype and when is it a distinct species? Researchers led by Una Morgan at Murdoch University in Western Australia offer a case for a distinct species of canine Cryptosporidium.

Currently, canine infections of Cryptosporidium are lumped under the species heading of C. parvum, the species implicated in human illnesses, based on morphological comparisons. However, based on sequence analysis of the Hsp-70 gene and 18S rDNA comparison, several dog-derived isolates were found to be identical to one another across geographic distances and distinct from other C. parvum isolates.

"The level of genetic divergence between the ‘dog’ genotype and other Cryptosporidium genotypes, combined with its apparently host-adapted nature, provides support that the ‘dog’ genotype may in fact be a separate species," Morgan says. "An accurate understanding of the transmission dynamics and epidemiology of Cryptosporidium is dependent on a sound taxonomy," she adds.

(U. M. Morgan, L. Xiao, P. Monis, A. Fall, P. J. Irwin, R. Fayer, K. M. Denholm, J. Limor, A. Lal, and R. C. A. Thompson. 2000. Cryptosporidium spp. in domestic dogs: the "dog" genotype. Appl. Environ. Microbiol. 66:2220–2223.) Abstract | Full Text

Transgenic and Unmodified Plant Roots Kill Nonpathogenic Bacteria

deVries and Wackernagel

Potato plants engineered to produce the T4 lysozyme against enterobacteria exhibited considerable killing of Bacillus subtilis cells on root surfaces, researchers found. However, Wilfried Wackernagel and his colleagues at the University of Oldenburg, Germany, also discovered lesser but still notable bactericidal effects from unmodified plant roots as well. To determine these killing effects, the researchers developed a novel method for in situ monitoring of interactions between plant roots and bacteria.

While the findings suggest that small quantities of lysozyme are secreted into the environment, their effects on bacterial communities in the rhizosphere likely involve complex interactions with plants’ natural defenses. The findings do not answer the question of whether the transgenic potatoes would have harmful effects on normal soil microbial communities. However, Wackernagel says, "T4-lysozyme production by the plants presently provides the only (and very promising) biological control of enterobacterial infection."

(I. Ahrenholtz, K. Harms, J. de Vries, and W. Wackernagel. 2000. Increased killing of Bacillus subtilis on the hair roots of transgenic T4 lysozyme-producing potatoes. Appl. Environ. Microbiol. 66:1862–1865.) Abstract | Full Text