Effects of acid challenge on in vivo and in vitro rat renal ammoniagenesis.

This study compares the ability of different strengths of NH₄Cl, CaCl₂, and HCl to affect the termporal excretion of ammonium in rats. Oral NH₄Cl given in a single dose of 0.5 mmole, 1.0 mmole and 1.5 mmole/100 g BW steadily increases ammonium excretion in rats. The majority of the augmented ammonium excretion is secondary to increased renal production — not to changes in urine pH or urine volume. Acute challenges greater than 1.5 mmole/100 g BW do not increase ammonium excretion further. Results were similar when chronic acid challenge was investigated — greater NH₄Cl challenges cause greater ammonium excretion. Challenges beyond 1.5 mmole/100 g BW bid frequently cause death unless the rats are preconditioned (made mildly acidotic) prior to initiation of this dose. At the 1.5 mmole/100 g BW dose, maximal ammonium excretion is reached by day 2 or 3. Thus, maximal renal ammoniagenesis during acid stress occurs rapidly, and at different times depending on the strength of the acid challenge. CaCl₂ or HCl offer no advantages over NH₄Cl as acidifying agents. In addition to the above, there is a significant correlation between ammonium excretion $\text{in vivo}$ and the ability of rat renal slices to produce ammonia from glutamine or glutamate $\text{in vitro}$.     

LAP3, a novel plant protein required for pollen development, is essential for proper exine formation

We isolated lap3-1 and lap3-2 mutants in a screen for pollen that displays abnormal stigma binding. Unlike wild-type pollen, lap3-1 and lap3-2 pollen exine is thinner, weaker, and is missing some connections between their roof-like tectum structures. We describe the mapping and identification of LAP3 as a novel gene that contains a repetitive motif found in β-propeller enzymes. Insertion mutations in LAP3 lead to male sterility. To investigate possible roles for LAP3 in pollen development, we assayed the metabolite profile of anther tissues containing developing pollen grains and found that the lap3-2 defect leads to a broad range of metabolic changes. The largest changes were seen in levels of a straight-chain hydrocarbon nonacosane and in naringenin chalcone, an obligate compound in the flavonoid biosynthesis pathway. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Social plasticity in non-territorial male African cichlid fish <Emphasis Type="Italic">Astatotilapia burtoni</Emphasis>

The African cichlid fish Astatotilapia burtoni represents a valuable model system for studies of social decision-making due to its socially mediated phenotypic plasticity. The males reversibly transition in social status from reproductively dominant and territorial (DOM) to submissive and non-territorial (SUB). Males are traditionally categorized into these two behavioral phenotypes by observational scoring. There is evidence, however, that this dichotomous categorization might not capture the behavioral plasticity displayed by individuals transitioning between SUB and DOM status. To test this concept, we used focal observations of intrasexual conflict behavior in fish communities combined with a modified analysis of the ethogram typically used in A. burtoni. Results revealed a cluster of males close to the crossover point between SUB and DOM status as defined by the traditional dominance index. These intermediate males showed the highest frequency of intrasexual conflict behaviors, distinct behavioral responses to threats, and body pigment signaling displays that distinguish them from prototypical SUBs and DOMs. As such, our results provide a noninvasive behavioral metric to categorize A. burtoni males into three groups, thus further capturing the complex social dynamic of this model organism.     

Plant defensins and virally encoded fungal toxin KP4 inhibit plant root growth

Plant defensins are small, highly stable, cysteine-rich antimicrobial proteins that are thought to constitute an important component of plant defense against fungal pathogens. There are a number of such defensins expressed in various plant tissues with differing antifungal activity and spectrum. Relatively little is known about the modes of action and biological roles of these proteins. Our previous work on a virally encoded fungal toxin, KP4, from Ustilago maydis and subsequently with the plant defensin, MsDef1, from Medicago sativa demonstrated that some of these proteins specifically blocked calcium channels in both fungi and animals. The results presented here demonstrate that KP4 and three plant defensins, MsDef1, MtDef2, and RsAFP2, all inhibit root growth in germinating Arabidopsis seeds at low micromolar concentrations. We have previously demonstrated that a fusion protein composed of Rab GTPase (RabA4b) and enhanced yellow fluorescent protein (EYFP) is dependent upon calcium gradients for localization to the tips of the growing root hairs in Arabidopsis thaliana. Using this tip-localized fusion protein, we demonstrate that all four proteins rapidly depolarize the growing root hair and block growth in a reversible manner. This inhibitory activity on root and root hair is not directly correlated with the antifungal activity of these proteins and suggests that plants apparently express targets for these antifungal proteins. The data presented here suggest that plant defensins may have roles in regulating plant growth and development. A. Allen and A.K. Snyder contributed equally.     

Multiple pathology in a Merowingian individual of a graveyard near Insheim (Rhineland-Pfalz)

The following case report describes in detail a 57 years old (+/- 5 years) male individual from a Franconian graveyard in Insheim, Province of Rhineland-Palatinate, dating to between the 6th and 7th century A.D. The individual displays a number of unusual pathologies. The atlas shows a complete aplasia of the posterior arch, probably resulting in a torticollis. The changed static induced a massive spondylar-arthrotic degeneration of the cervical spine on the right-lateral portion. On the fronto-parietal section two fractures are visible which were caused by a sharp and violent force. The area in question measures 7 by 10 cm. It has healed in a dislocated position. The second location displays marks of a 6 cm long sword-cut which did strike the skull obtusely on the left parietal. In addition to the above the skull displays on its right side a great number of small circular hole defects which also appear on ribs, vertebrae, clavicula and the mandible. They present the typical picture of a plasmocytoma. As an expression of a secondary hyperparathyreoidism one can recognize ossifications of soft tissue on the calcaneus, tibia, fibula and patella as well as intravital loss of mandibular dentition. It is quite remarkable that the individual reached a relative old age despite of his numerous and serious physical encroachments due to the apparent and obvious intentions of his aggressive contemporaries to kill him.     

Wet wound healing

Wound treatment in a flexible transparent chamber attached to the perimeter of the wound and containing a liquid has been extensively tested in preclinical experiments in pigs and found to offer several advantages. It protects the wound; the liquid medium or saline in the chamber provides in vivo tissue culture-like conditions; and antibiotics, analgesics, and various molecules can be delivered to the wound through the chamber. The wound chamber causes no injury to the wound itself or to the surrounding intact skin. Topical delivery of, for instance, antibiotics can provide very high concentrations at the wound site and with a favorable direction of the concentration gradient. A series of 28 wounds in 20 patients were treated with a wound chamber containing saline and antibiotics. Most patients had significant comorbidity and had not responded to conservative or surgical management with débridement and delayed primary closure or skin grafts. Six wounds had foreign bodies present; four of these were joint prostheses. Seven patients were on corticosteroids for rheumatoid arthritis, lupus, or chronic obstructive pulmonary disease, and four patients had diabetes. Most patients were treated with the wound chamber in preparation for a delayed skin graft or flap procedure, but one was treated with a wound chamber until the wound healed. Twenty-five of the wounds (89 percent) healed, and five wounds (18 percent) required additional conservative management after the initial chamber treatment and grafting procedure. Of the three wounds that did not heal, one healed after additional chamber treatment, one had a skin graft that did not take, and one required reamputation at a higher level. Antibiotic delivery was less than one intravenous dose daily, which avoided the potential for systemic absorption to toxic levels. Antibiotics such as vancomycin and gentamicin could be used in concentrations of up to 10,000 times the minimal inhibitory concentration. Forty-eight hours after application, 20 percent or more of the original antibiotic concentration was present in the wound chamber fluid. In conclusion, the wound chamber provides a safe, powerful tool in the treatment of difficult infected wounds.