1.56 Å structure of mature truncated human fibroblast collagenase

The X-ray crystal structure of a 19 kDa active fragment of human fibroblast collagenase has been determined by the multiple isomorphous replacement method and refined at 1.56 Å resolution to an R-factor of 17.4%. The current structure includes a bound hydroxamate inhibitor, 88 waters and three metal atoms (two zincs and a calcium). The overall topology of the enzyme, comprised of a five stranded β-sheet and three α-helices, is similar to the thermolysin-like metalloproteinases. There are some important differences between the collagenase and thermolysin families of enzymes. The active site zinc ligands are all histidines (His-218, His-222, and His-228). The presence of a second zinc ion in a structural role is a unique feature of the matrix metalloproteinases. The binding properties of the active site cleft are more dependent on the main chain conformation of the enzyme (and substrate) compared with thermolysin. A mechanism of action for peptide cleavage similar to that of thermolysin is proposed for fibroblast collagenase. © 1994 Wiley-Liss, Inc.     

Mortality rates of desert vegetation during high-intensity drought at Uluru-Kata Tjuta National Park,Central Australia

Precipitation variability and heatwaves are expected to intensify over much of inland Australia under most projected climate change scenarios. This will undoubtedly have impacts on the biota of Australian dryland systems. However, accurate modelling of these impacts is presently impeded by a lack of empirical research on drought/heatwave effects on native arid flora and fauna. During the 2018–2021 Australian drought, many parts of the continent's inland experienced their hottest, driest period on record. Here, we present the results of a field survey in 2021 involving indigenous rangers, scientists and national parks staff who assessed plant dieback during this drought at Ulur u-Kata Tjut a National Park (UKTNP), central Australia. Spatially randomized quadrat sampling of eight common and culturally important plants indicated the following plant death rates across UKTNP (in order of drought susceptibility): desert myrtle (Aluta maisonneuvei subsp. maisonneuvei) (91%), yellow flame grevillea (Grevillea eriostachya) (79%), Maitland's wattle (Acacia maitlandii) (67%), waxy wattle (A. melleodora) (65%), soft spinifex grass (Triodia pungens) (53%), mulga (A. aneura) (42%), desert oak (Allocasuarina decaisneana) (22%) and quandong (Santalum acuminatum) (0%). The sampling also detected that seedling recruitment was absent or minimal for all plants except soft spinifex, while a generalized linear mixed model (GLMM) indicated two-way interactions among species, plant size and stand density as important predictors of drought survival of adult plants. A substantial loss of biodiversity has occurred at UKTNP during the recent drought, with likely drivers of widespread plant mortality being extreme multi-year rainfall deficit (2019 recorded the lowest-ever annual rainfall at UKTNP [27 mm]) and record high summer temperatures (December 2019 recorded the highest-ever temperature [47.1°C]). Our findings indicate that widespread plant death and extensive vegetation restructuring will occur across arid Australia if the severity and frequency of droughts increase under climate change.     

Effects of pre-adult and adult experience on host acceptance in choice and non-choice tests in two strains ofTrichogramma

The effect of adult learning through an oviposition experience, and pre-adult learning through development inside a host was investigated in two strains of an Australian egg parasitoid,Trichogramma nrivelae (Hymenoptera: Trichogrammatidae). Host response was measured in two types of laboratory preference tests. In single host tests, females reared on three lepidopteran hosts (Heliothis punctigera (Noctuidae),Papilio aegeus (Papilionidae), andHypolimnas bolina (Nymphalinae)) were presented host eggs individually, and allowed two ovipositions. Pre-adult experience affected host preference in only one strain, while acceptance of a host was increased in both strains when they had previously oviposited in this host species. An oviposition experience had a stronger effect on host preference than pre-adult experience. In choice tests, pairwise combinations of hosts were arranged in an alternating grid. The ratio of host acceptances to host contacts was computed for the whole test and up to the first oviposition. These indicated that effects of rearing host were weak or absent, but the host chosen initially had a strong effect on host preference. Relative size of the hosts had a strong effect on choice of the first host. The implications of learning inTrichogramma are discussed in relation to host preference testing procedures and the selection of candidate strains for mass rearing and inundative release.     

Genetics of high level penicillin resistance in clinical isolates of Streptococcus pneumoniae

Abstract Mosaic penicillin-binding proteins (PBP) 1A, 2X and 2B genes were cloned from four clinical isolates of Streptococcus pneumoniae with levels of susceptibility to penicillin ranging from 1.5 to 16 μg benzylpenicillin ml⁻¹. In each instance it was possible to transform either the penicillin-sensitive laboratory strain R6 or a sensitive clinical isolate 110K/70 to the full level of penicillin resistance with these three penicillin-binding proteins alone. Until now it has not been possible to clearly determine whether alterations to PBP1A, 2X and 2B alone were sufficient to attain high level penicillin resistance.     

Gastric cytoprotection by intracisternal interleukin-1 beta in the rat

The effects of intracisternal (ic) injection of recombinant interleukin-1 beta (IL-1) on absolute ethanol-induced gastric necrotic lesions were studied in conscious rats. IL-1 given ic inhibited ethanol-induced gastric lesions. The cytoprotective effect was dose dependent (ED175 ng/rat), long lasting with a maximal action when given 1-3 h prior to ethanol, blocked by ic injection of a IL-1 receptor antagonist protein (IRAP), and by intraperitoneal injection of indomethacin. IL-1, injected ic, was detected in the peripheral blood. However, IL-1 serum levels were lower after IL-1 injection ic than after ip at a dose giving equal gastric protection. These data show that ic IL-1 induces long lasting gastric protection mediated by interaction with IL-1 receptors and prostaglandin pathways at central and/or peripheral sites that remain to be localized.     

Linking behavioral states to landscape features for improved conservation management

1. A central theme for conservation is understanding how animals differentially use, and are affected by change in, the landscapes they inhabit. However, it has been challenging to develop conservation schemes for habitat‐specific behaviors.
2. Here we use behavioral change point analysis to identify behavioral states of golden eagles (Aquila chrysaetos) in the Sonoran and Mojave Deserts of the southwestern United States, and we identify, for each behavioral state, conservation‐relevant habitat associations.
3. We modeled behavior using 186,859 GPS points from 48 eagles and identified 2,851 distinct segments comprising four behavioral states. Altitude above ground level (AGL) best differentiated behavioral states, with two clusters of short‐distance movement behaviors characterized by low AGL (state 1 AGL = 14 m (median); state 2 AGL = 11 m) and two associated with longer‐distance movement behaviors and characterized by higher AGL (state 3 AGL = 108 m; state 4 AGL = 450 m).
4. Behaviors such as perching and low‐altitude hunting were associated with short‐distance movements in updraft‐poor environments, at higher elevations, and over steeper and more north‐facing terrain. In contrast, medium‐distance movements such as hunting and transiting were over gentle and south‐facing slopes. Long‐distance transiting occurred over the desert habitats that generate the best updraft.
5. This information can guide management of this species, and our approach provides a template for behavior‐specific habitat associations for other species of management concern.

     

Fitness consequences of redundant cues of competition in male Drosophila melanogaster

Phenotypic plasticity can allow animals to adapt their behavior, such as their mating effort, to their social and sexual environment. However, this relies on the individual receiving accurate and reliable cues of the environmental conditions. This can be achieved via the receipt of multimodal cues, which may provide redundancy and robustness. Male Drosophila melanogaster detect presence of rivals via combinations of any two or more redundant cue components (sound, smell, and touch) and respond by extending their subsequent mating duration, which is associated with higher reproductive success. Although alternative combinations of cues of rival presence have previously been found to elicit equivalent increases in mating duration and offspring production, their redundancy in securing success under sperm competition has not previously been tested. Here, we explicitly test this by exposing male D. melanogaster to alternative combinations of rival cues, and examine reproductive success in both the presence and absence of sperm competition. The results supported previous findings of redundancy of cues in terms of behavioral responses. However, there was no evidence of reproductive benefits accrued by extending mating duration in response to rivals. The lack of identifiable fitness benefits of longer mating under these conditions, both in the presence and absence of sperm competition, contrasted with some previous results, but could be explained by (a) damage sustained from aggressive interactions with rivals leading to reduced ability to increase ejaculate investment, (b) presence of features of the social environment, such as male and female mating status, that obscured the fitness benefits of longer mating, and (c) decoupling of behavioral investment with fitness benefits.     

Chemical components of ginseng,their biotransformation products and their potential as treatment of hypertension

Molecular and Cellular Biochemistry - Ginseng is an ancient perennial herb belonging to the family Araliaceae and genus Panax which has been used for medical therapeutics for thousands of years,...