Obligate mating of females (queens) with multiple males has evolved only rarely in social Hymenoptera (ants, social bees, social wasps) and for reasons that are fundamentally different from those ...underlying multiple mating in other animals. The monophyletic tribe of 'attin') fungus-growing ants is known to include evolutionarily derived genera with obligate multiple mating (the Acromyrmex and Atta leafcutter ants) as well as phylogenetically basal genera with exclusively single mating (e.g. Apterostigma, Cyphomyrmex, Myrmicocrypta). All attine genera share the unique characteristic of obligate dependence on symbiotic fungus gardens for food, but the sophistication of this symbiosis differs considerably across genera. The lower attine genera generally have small, short-lived colonies and relatively non-specialized fungal symbionts (capable of living independently of their ant hosts), whereas the four evolutionarily derived higher attine genera have highly specialized, long-term clonal symbionts. In this paper, we investigate whether the transition from single to multiple mating occurred relatively recently in the evolution of the attine ants, in conjunction with the novel herbivorous 'leafcutte' niche acquired by the common ancestor of Acromyrmex and Atta, or earlier, at the transition to rearing specialized long-term clonal fungi in the common ancestor of the larger group of higher attines that also includes the genera Trachymyrmex and Sericomyrmex. We use DNA microsatellite analysis to provide unambiguous evidence for a single, late and abrupt evolutionary transition from exclusively single to obligatory multiple mating. This transition is historically correlated with other evolutionary innovations, including the extensive use of fresh vegetation as substrate for the fungus garden, a massive increase in mature colony size and morphological differentiation of the worker caste.
All known fungus-growing ants (tribe Attini) are obligately symbiotic with their cultivated fungi. The fungal cultivars of “lower” attine ants are facultative symbionts, capable of living apart from ...ants, whereas the fungal cultivars of “higher” attine ants, including leaf-cutting genera Atta and Acromyrmex, are highly specialized, obligate symbionts. Since higher attine ants and fungi are derived from lower attine ants and fungi, understanding the evolutionary transition from lower to higher attine agriculture requires understanding the historical sequence of change in both ants and fungi. The biology of the poorly known ant genus Mycetagroicus is of special interest in this regard because it occupies a phylogenetic position intermediate between lower and higher ant agriculture. Here, based on the excavations of four nests in Pará, Brazil, we report the first biological data for the recently described species Mycetagroicus inflatus, including the first descriptions of Mycetagroicus males and larvae. Like M. cerradensis, the only other species in the genus for which nesting biology is known, the garden chambers of M. inflatus are unusually deep and the garden is most likely relocated vertically in rainy and dry seasons. Due to the proximity of nests to the Araguaia River, it is likely that even the uppermost chambers and nest entrances of M. inflatus are submerged during the rainy season. Most remarkably, all three examined colonies of M. inflatus cultivate the same fungal species as their congener, M. cerradensis, over 1,000 km away, raising the possibility of long-term symbiont fidelity spanning speciation events within the genus.
Fungus-farming “attine” ant agriculture consists of five distinct agricultural systems characterized by a remarkable symbiont fidelity in which five phylogenetic groups of ants faithfully cultivate ...five phylogenetic groups of fungi. Across-system garden switching experiments result in colony decline and death, indicating that attine ant-fungus symbiont fidelity is enforced by poorly understood biological constraints. The most dramatic violation of this pattern of symbiont fidelity occurs in the relict species
Apterostigma megacephala
, the only lower-attine ant known to cultivate a higher-attine fungus.
Apterostigma megacephala
is the sole surviving representative of an ancient lineage that diverged from all other
Apterostigma
fungus-farming ants ~39 million years ago, yet it cultivates
Leucoagaricus gongylophorus
, a highly domesticated fungal species that originated in the gardens of the recently evolved leaf-cutting ants 8–11 million years ago. Understanding the biology of
A. megacephala
, therefore, may provide important clues about the biological mechanisms that constrain the otherwise seemingly obligate ant-fungus associations that characterize attine ant agriculture. Here, based on field work in the Floresta Nacional de Carajás in the state of Pará in Brazil, we report the previously unknown biology of
A. megacephala
, including nest architecture, colony demography, foraging behavior, and the morphologies of the previously undescribed gyne, male, and larva.
Background
Microdialysis is a well-established technology that can be used for continuous blood glucose monitoring. We determined point and trend accuracy, and reliability of a microdialysis-based ...continuous blood glucose-monitoring device (EIRUS
®
) in critically ill patients.
Methods
Prospective study involving patients with an expected intensive care unit stay of ≥48 h. Every 15 min, device readings were compared with blood glucose values measured in arterial blood during blocks of 8 h per day for a maximum of 3 days. The Clarke error grid, Bland–Altman plot, mean absolute relative difference and glucose prediction error analysis were used to express point accuracy and the rate error grid to express trend accuracy. Reliability testing included aspects of the device and the external sensor, and the special central venous catheter (CVC) with a semipermeable membrane for use with this device.
Results
We collected 594 paired values in 12 patients (65 26–80; 8–97 (median IQR; total range) paired values per patient). Point accuracy: 93.6 % of paired values were in zone A of the Clarke error grid, 6.4 % were in zone B; bias was 4.1 mg/dL with an upper limit of agreement of 28.6 mg/dL and a lower level of agreement of −20.5 mg/dL in the Bland–Altman analysis; 93.6 % of the values ≥75 mg/dL were within 20 % of the reference values in the glucose prediction error analysis; the mean absolute relative difference was 7.5 %. Trend accuracy: 96.4 % of the paired values were in zone A, and 3.3 and 0.3 % were in zone B and zone C of the rate error grid. Reliability: out of 16 sensors, 4 had to be replaced prematurely; out of 12 CVCs, two malfunctioned (one after unintentional flushing by unsupervised nurses of the ports connected to the internal microdialysis chamber, causing rupture of the semipermeable membrane; one for an unknown reason). Device start-up time was 58 56–67 min; availability of real-time data was 100 % of the connection time.
Conclusions
In this study in critically ill patients who had no hypoglycemic episodes and a limited number of hyperglycemic excursions, point accuracy of the device was moderate to good. Trend accuracy was very good. The device had no downtimes, but 4 out of 16 external sensors and 2 out of 12 CVCs had practical problems.
CONTEXT.— This study examined the impact of retracted articles on biomedical communication. OBJECTIVE.— To examine publications identified in the biomedical literature as having
been retracted, to ...ascertain why and by whom the publications were retracted
and to what extent citations of later-retracted articles continue to be incorporated
in subsequent work. DESIGN.— A search of MEDLINE from 1966 through August 1997 for articles that
had been retracted. MAIN OUTCOME MEASURES.— Characteristics of retractions and citations to articles after
retraction. RESULTS.— A total of 235 articles had been retracted. Error was acknowledged in
relation to 91 articles; results could not be replicated in 38; misconduct
was evident in 86; and no clear reason was given in 20. Of the 235 articles,
190 were retracted by some or all of the authors; 45 were retracted by a person
or organization other than the author(s). The 235 retracted articles were
cited 2034 times after the retraction notice. Examination of 299 of those
citations reveals that in only 19 instances was the retraction noted; the
remaining 280 citations treated the retracted article either explicitly (n=17)
or implicitly (n=263) as though it were valid research. CONCLUSION.— Retracted articles continue to be cited as valid work in the biomedical
literature after publication of the retraction; these citations signal potential
problems for biomedical science.
Synchronous bilateral breast cancer (SBBC) poses distinct challenges for radiation therapy planning. We report our proton therapy experience in treating patients with SBBC. We also provide a ...dosimetric comparison of intensity modulated proton therapy (IMPT) versus photon therapy.
Patients with SBBC who received IMPT at our institution were retrospectively analyzed. The clinical target volume (CTV) included the breast or chest wall and comprehensive regional lymph nodes, including axilla, supraclavicular fossa, and the internal mammary chain. Intensity modulated proton therapy and volumetric modulated arc therapy (VMAT) plans were generated with the goal that 90% of the CTV would recieve at least 90% of the prescription dose (D90>=90%). Comparisons between modalities were made using the Wilcoxon signed rank test. Physician-reported acute toxic effects and photography were collected at baseline, end of treatment, and each follow-up visit.
Between 2015 and 2018, 11 patients with SBBC were treated with IMPT. The prescription was 50 Gy in 25 fractions. The median CTV D90 was 99.9% for IMPT and 97.6% for VMAT (P = .001). The mean heart dose was 0.7 Gy versus 7.2 Gy (P = .001), the total lung mean dose was 7.8 Gy versus 17.3 Gy (P = .001), and the total lung volume recieving 20 Gy was 13.0% versus 27.4% (P = .001). The most common acute toxic effects were dermatitis (mostly grade 1-2 with 1 case of grade 3) and grade 1 to 2 fatigue. The most common toxic effects at the last-follow up (median, 32 months) were grade 1 skin hyperpigmentation, superficial fibrosis, and extremity lymphedema. No nondermatologic or nonfatigue adverse events of grade >1 were recorded.
Bilateral breast and/or chest wall and comprehensive nodal IMPT is technically feasible and associated with low rates of severe acute toxic effects. Treatment with IMPT offered improved target coverage and normal-tissue sparing compared with photon therapy. Long-term follow-up is ongoing to assess efficacy and toxic effects.
Angiotensin II (Ang II), a potent hypertrophic stimulus, causes significant increases in TGFb1 gene expression. However, it is not known whether there is a causal relationship between increased ...levels of TGF- beta 1 and cardiac hypertrophy. Echocardiographic analysis revealed that TGF- beta 1-deficient mice subjected to chronic subpressor doses of Ang II had no significant change in left ventricular (LV) mass and percent fractional shortening during Ang IItreatment. In contrast, Ang II-treated wild-type mice showed a >20% increase in LV mass and impaired cardiac function. Cardiomyocyte cross-sectional area was also markedly increased in Ang II-treated wild-type mice but unchanged in Ang II-treated TGF- beta 1-deficient mice. No significant levels of fibrosis, mitotic growth, or cytokine infiltration were detected in Ang II-treated mice. Atrial natriuretic factor expression was similar to 6-fold elevated in Ang II-treated wild-type, but not TGF- beta 1-deficient mice. However, the alpha - to beta -myosin heavy chain switch did not occur in Ang II-treated mice, indicating that isoform switching is not obligatorily coupled with hypertrophy or TGF- beta 1. The Ang II effect on hypertrophy was shown not to result from stimulation of the endogenous renin-angiotensis system. These results indicate that TGF- beta 1 is an important mediator of the hypertrophic growth response of the heart to Ang II.
Amenthes Rupes overlies one of the largest thrust faults on Mars, with structural topography accurately measured by MOLA. Forward mechanical models successfully predict the surface topography across ...this large contractional structure. The best‐fitting fault parameters are: fault dip angle, 25‐30°; depth of faulting, 25‐30 km; and fault offset, 1.5 km. These first‐order results are insensitive to either the offset distribution along the fault or crustal material properties. Both very shallow (e.g., ∼15 km) and very deep (∼45 km) depths of faulting can be ruled out, as can significantly different dips and offset magnitudes. Amenthes Rupes may span the ancient seismogenic lithosphere in the Martian Noachian highlands, implying maximum values at the time of faulting for heat flux of ∼54‐70 mW m−2 and paleogeothermal gradient of 15‐20 K km−1.
1 Exercise Physiology
Laboratory, School of Education, The Flinders University of South
Australia, Adelaide, South Australia 5001;
2 Department of Nuclear Medicine,
Royal Adelaide Hospital, ...Adelaide, South Australia 5000; and
3 Commonwealth Scientific and
Industrial Research Organization, Division of Water Resources, Glen
Osmond, South Australia 5064, Australia
This study compared the traditional
two-compartment (fat mass or FM; fat free mass or FFM)
hydrodensitometric method of body composition measurement, which is
based on body density, with three (FM, total body water or TBW, fat
free dry mass)- and four (FM, TBW, bone mineral mass or BMM,
residual)-compartment models in highly trained men
( n = 12), sedentary men
( n = 12), highly trained women
( n = 12), and sedentary women
( n = 12). The means and
variances for the relative body fat (%BF) differences between the two-
and three-compartment models 2.2 ± 1.6 (SD) % BF;
n = 48 were significantly
greater ( P 0.02) than those between the three- and four-compartment models (0.2 ± 0.3% BF;
n = 48) for all four groups. The
three-compartment model is more valid than the two-compartment
hydrodensitometric model because it controls for biological variability
in TBW, but additional control for interindividual variability in BMM
via the four-compartment model achieves little extra accuracy. The
combined group ( n = 48) exhibited greater ( P < 0.001) FFM densities
(1.1075 ± 0.0049 g/cm 3 ) than
the hydrodensitometric assumption of 1.1000 g/cm 3 , which is based on analyses
of three male cadavers aged 25, 35, and 46 yr. This was primarily
because their FFM hydration (72.4 ± 1.1%;
n = 48) was lower
( P 0.001) than the
hydrodensitometric assumption of 73.72%.
hydrodensitometry; total body water; dual-energy X-ray
absorptiometry; sedentary subjects; endurance athletes
Ribonuclease A Variants with Potent Cytotoxic Activity Leland, Peter A.; Schultz, L. Wayne; Kim, Byung-Moon ...
Proceedings of the National Academy of Sciences - PNAS,
09/1998, Letnik:
95, Številka:
18
Journal Article
Recenzirano
Odprti dostop
Select members of the bovine pancreatic ribonuclease A (RNase A) superfamily are potent cytotoxins. These cytotoxic ribonucleases enter the cytosol, where they degrade cellular RNA and cause cell ...death. Ribonuclease inhibitor (RI), a cytosolic protein, binds to members of the RNase A superfamily with inhibition constants that span 10 orders of magnitude. Here, we show that the affinity of a ribonuclease for RI plays an integral role in defining the potency of a cytotoxic ribonuclease. RNase A is not cytotoxic and binds RI with high affinity. Onconase, a cytotoxic RNase A homolog, binds RI with low affinity. To disrupt the RI-RNase A interaction, three RNase A residues (Asp-38, Gly-88, and Ala-109) that form multiple contacts with RI were replaced with arginine. Replacing Asp-38 and Ala-109 with an arginine residue has no effect on the RI-RNase interaction. In addition, these variants are not cytotoxic. In contrast, replacing Gly-88 with an arginine residue yields a ribonuclease (G88R RNase A) that retains catalytic activity in the presence of RI and is cytotoxic to a transformed cell line. Replacing Gly-88 with aspartate also yields a ribonuclease (G88D RNase A) with a decreased affinity for RI and cytotoxic activity. The cytotoxic potency of onconase, G88R RNase A, and G88D RNase A correlate with RI evasion. We conclude that ribonucleases that retain catalytic activity in the presence of RI are cytotoxins. This finding portends the development of a class of chemotherapeutic agents based on pancreatic ribonucleases.
PDF
