Transformation of Saccharomyces cerevisiae with yeast mitochondrial DNA linked to two micron circular yeast plasmid

Mitochondrial DNA from a petite mutant of yeast carrying an oligomycin resistance determinant has been ligated in vitro to 2 μm yeast plasmid DNA. The recombinant DNA so produced has been used to transform an oligomycin sensitive strain of Saccharomyces cerevisiae to oligomycin resistance at a frequency approaching 50 times the spontaneous mutation rate to oligomycin resistance. The majority of transformants showed genetic properties suggesting that recombination between the transforming DNA and the resident mtDNA has occurred. The properties of a subclass of oligomycin resistance transformants suggested that in these cells the transforming DNA has not become stably integrated into the mitochondrial genome of the recipient cell.     

Effects of general anesthetics on search in memory in man.

Recovery of search functions in long-term memory following several hours of anesthesia was studied on human volunteers. Verbal as well as visual search was assessed. The anesthetics used, fluroxene and halothane, slowed down considerably the verbal search for the first few hours following anesthesia, but had very little effect on the following day. No effect was observed a week later. Visual search was not affected at all, in accordance with previous findings indicating a selective effect of low concentrations of inhalation anesthetics on verbal memory.     

Identification of a soluble protein stimulator of plasmalogen biosynthesis and stearoyl-coenzyme a desaturase

Stimulation of the desaturation of 1-alkyl-2-acyl-sn-glycero-3-phosphoethanolamine (GPE), which forms ethanolamine plasmalogens, by a component of the 105,000g supernatant has been previously reported. We have isolated the stimulatory protein and identified it as catalase. Purified rat liver catalase or commercial bovine liver catalase is as effective in stimulating microsomal 1-alkyl-2-acyl-GPE desaturation as the soluble proteins. The stimulatory effect of these proteins is eliminated by catalase inhibitors. It appears that catalase stimulates the desaturation of 1-alkyl-2-acyl-GPE by preventing inactivation of the enzyme system by H₂O₂ or a decomposition product of H₂O₂. The cytochrome b₅ content and NADH oxidation are depressed in Fischer R-3259 sarcoma microsomes by H₂O₂; this effect is eliminated by catalase. However, since measurable inhibition of 1-alkyl-2-acyl-GPE desaturase by H₂O₂ still occurred in the presence of catalase, the inhibition by H₂O₂ cannot be explained solely on the basis of cytochrome b₅ inactivation. The desaturation of stearoyl-coenzyme A, a reaction analogous in many respects to 1-alkyl-2-acyl-GPE desaturation, was also found to be stimulated by catalase.     

Relationship between the chromatoid body and the acrosomal system in early spermatids of Myxine glutinosa L.

Summary A transient close relationship between the chromatoid body and the developing acrosome is demonstrated in early spermatids of Myxine glutinosa.This work was supported by the Norwegian Research Council for Science and Humanities (NAVF, Grant Nr. D 61.44) and the Austrian Fonds zur Förderung der wissenschaftlichen Forschung, Projekt 2183     

Cell surface charge and regulation of cell division of 3T3 cells and transformed derivatives.

The cell surface charge of 3T3, 3T6, SV40-3T3 cells and trypsin-, neuraminidase- and serumtreated preparations of these has been characterized by microcell electrophoresis. At 25 °C, density-inhibited 3T3 cells show a decrease in electrophoretic mobility when treated with various stimuli of cell division. This effect is not observed at 25 °C for transformed derivatives. The surface charge configuration of various cell preparations exhibits a thermal transition which is located within a temperature range characteristic of each preparation. These and other results from cell electrophoresis, taken together with those obtained in agglutination studies by other authors, are considered evidence for the occurrence in the plasma membrane of these cells of a twodimensional phase separation. The temperature range of this phase separation is shifted on treating the cells by growth stimuli. This effect might be an indication of a basic trigger mechanism in the cell cycle.     

The effect of streptococcus on the persistence of Brugia malayi and on the production of elephantiasis in cats

Cats were exposed to 200 Brugia malayi larvae on one hind foot over a 3 week period. Six weeks after the initial exposure to B. malayi, 10 of the cats were challenged on both hind legs with a Group G streptococcus. The remaining 10 cats were not exposed to the streptococcus. Following bacterial challenge, the B. malayi-infected leg of 9 of 10 cats displayed sequelae including erysipelas and abscesses. In addition, 5 of the affected legs had an elephantoid appearance, both by gross observation and as seen at necropsy 10 weeks after the initial B. malayi infection. The contralateral, uninfected leg of each cat remained normal in appearance. Histologic processing and examination of the elephantoid tissue showed it to be collagen; eosinophils and mast cells were plentiful in the collagen matrix. In the controls, only 1 animal displayed erysipelas and no abscesses were seen. Lymphedema seen in the B. malayi-infected leg of 5 control cats was less extensive than in uninfected cats challenged with streptococci and at necropsy no significant collagen matrix was evident. The location and number of worms in the lymphatics were noted. This study demonstrated that secondary microbial infections can contribute to the causation of elephantiasis under certain circumstances and that developing B. malayi were in some way adversely affected by the streptococcal involvement of the filaria-infected lymphatics.     

The antagonism by anti-inflammatory analgesics of prostaglandin F2α-induced contractions of human and rabbit myometrium

The anti-inflammatory analgesic drugs, aspirin, indomethacin, phenylbutazone, mefenamic acid, ibuprofen and flurbiprofen are shown to inhibit in a dose-dependent manner the force of contraction of isolated human pregnant myometrial strips which have been stimulated to contract by adding prostaglandin (PG) F_2α to the tissue bath. These drugs and also flufenamic acid and salicin show a similar antagonism of the action of PGF_2α with isolated rabbit non-pregnant myometrium. The ratio of the inhibitory concentration to the maximum plasma level after a normal dose suggests that phenylbutazone and possibly ibuprofen may be capable of inhibiting human uterine contractions . Patients who were treated with aspirin during induction of abortion using PGF_2α during the second trimester of pregnancy showed no significant change in the induction-abortion interval compared with patients not taking aspirin.     

Sensitivity of the S1 neuronal calcium network to insulin and Bay‐K 8644 in vivo: Relationship to gait,motivation, and aging processes

Neuronal hippocampal Ca²⁺ dysregulation is a critical component of cognitive decline in brain aging and Alzheimer''s disease and is suggested to impact communication and excitability through the activation of a larger after hyperpolarization. However, few studies have tested for the presence of Ca²⁺ dysregulation in vivo, how it manifests, and whether it impacts network function across hundreds of neurons. Here, we tested for neuronal Ca²⁺ network dysregulation in vivo in the primary somatosensory cortex (S1) of anesthetized young and aged male Fisher 344 rats using single‐cell resolution techniques. Because S1 is involved in sensory discrimination and proprioception, we tested for alterations in ambulatory performance in the aged animal and investigated two potential pathways underlying these central aging‐ and Ca²⁺‐dependent changes. Compared to young, aged animals displayed increased overall activity and connectivity of the network as well as decreased ambulatory speed. In aged animals, intranasal insulin (INI) increased network synchronicity and ambulatory speed. Importantly, in young animals, delivery of the L‐type voltage‐gated Ca²⁺ channel modifier Bay‐K 8644 altered network properties, replicating some of the changes seen in the older animal. These results suggest that hippocampal Ca²⁺ dysregulation may be generalizable to other areas, such as S1, and might engage modalities that are associated with locomotor stability and motivation to ambulate. Further, given the safety profile of INI in the clinic and the evidence presented here showing that this central dysregulation is sensitive to insulin, we suggest that these processes can be targeted to potentially increase motivation and coordination while also reducing fall frequency with age.     

Reversible bacteriophage resistance by shedding the bacterial cell wall

Phages are highly abundant in the environment and pose a major threat for bacteria. Therefore, bacteria have evolved sophisticated defence systems to withstand phage attacks. Here, we describe a previously unknown mechanism by which mono- and diderm bacteria survive infection with diverse lytic phages. Phage exposure leads to a rapid and near-complete conversion of walled cells to a cell-wall-deficient state, which remains viable in osmoprotective conditions and can revert to the walled state. While shedding the cell wall dramatically reduces the number of progeny phages produced by the host, it does not always preclude phage infection. Altogether, these results show that the formation of cell-wall-deficient cells prevents complete eradication of the bacterial population and suggest that cell wall deficiency may potentially limit the efficacy of phage therapy, especially in highly osmotic environments or when used together with antibiotics that target the cell wall.     

Demographic responses to climate‐driven variation in habitat quality across the annual cycle of a migratory bird species

The demography and dynamics of migratory bird populations depend on patterns of movement and habitat quality across the annual cycle. We leveraged archival GPS‐tagging data, climate data, remote‐sensed vegetation data, and bird‐banding data to better understand the dynamics of black‐headed grosbeak (Pheucticus melanocephalus) populations in two breeding regions, the coast and Central Valley of California (Coastal California) and the Sierra Nevada mountain range (Sierra Nevada), over 28 years (1992–2019). Drought conditions across the annual cycle and rainfall timing on the molting grounds influenced seasonal habitat characteristics, including vegetation greenness and phenology (maturity dates). We developed a novel integrated population model with population state informed by adult capture data, recruitment rates informed by age‐specific capture data and climate covariates, and survival rates informed by adult capture–mark–recapture data and climate covariates. Population size was relatively variable among years for Coastal California, where numbers of recruits and survivors were positively correlated, and years of population increase were largely driven by recruitment. In the Sierra Nevada, population size was more consistent and showed stronger evidence of population regulation (numbers of recruits and survivors negatively correlated). Neither region showed evidence of long‐term population trend. We found only weak support for most climate–demographic rate relationships. However, recruitment rates for the Coastal California region were higher when rainfall was relatively early on the molting grounds and when wintering grounds were relatively cool and wet. We suggest that our approach of integrating movement, climate, and demographic data within a novel modeling framework can provide a useful method for better understanding the dynamics of broadly distributed migratory species.