scholarly journals Complex axial growth patterns in an early Cambrian trilobite from South Australia

2021 ◽  
Vol 288 (1965) ◽  
Author(s):  
James D. Holmes ◽  
John R. Paterson ◽  
Diego C. García-Bellido
Keyword(s):  
Growth Regulation ◽  
South Australia ◽  
Growth Dynamics ◽  
Growth Patterns ◽  
Abrupt Changes ◽  
Cambrian Trilobite ◽  
Body Segmentation ◽  
Two Phases ◽  
Growth Controls ◽  
Axial Growth

The exceptional fossil record of trilobites provides our best window on developmental processes in early euarthropods, but data on growth dynamics are limited. Here, we analyse post-embryonic axial growth in the Cambrian trilobite Estaingia bilobata from the Emu Bay Shale, South Australia. Using threshold models, we show that abrupt changes in growth trajectories of different body sections occurred in two phases, closely associated with the anamorphic/epimorphic and meraspid/holaspid transitions. These changes are similar to the progression to sexual maturity seen in certain extant euarthropods and suggest that the onset of maturity coincided with the commencement of the holaspid period. We also conduct hypothesis testing to reveal the likely controls of observed axial growth gradients and suggest that size may better explain growth patterns than moult stage. The two phases of allometric change in E. bilobata , as well as probable differing growth regulation in the earliest post-embryonic stages, suggest that observed body segmentation patterns in this trilobite were the result of a complex series of changing growth controls that characterized different ontogenetic intervals. This indicates that trilobite development is more complex than previously thought, even in early members of the clade.

Distinctive diel growth cycles in leaves and cladodes of CAM plants: differences from C3 plants and putative interactions with substrate availability, turgor and cytoplasmic pH

2005 ◽  
Vol 32 (5) ◽  
pp. 421 ◽  
Author(s):  
Liezel M. Gouws ◽  
C. Barry Osmond ◽  
Ulrich Schurr ◽  
Achim Walter
Keyword(s):  
Malic Acid ◽  
Growth Dynamics ◽  
Maximum Growth ◽  
Co2 Assimilation ◽  
Growth Patterns ◽  
Phase Iii ◽  
C3 Plants ◽  
Cytoplasmic Ph ◽  
Cam Plants ◽  
Cell Turgor

Distinct diel rhythms of leaf and cladode expansion growth were obtained in crassulacean acid metabolism (CAM) plants under water-limited conditions, with maxima at mid-day during phase III of CO2 assimilation. This pattern coincided with the availability of CO2 for photosynthesis and growth during the decarboxylation of malic acid, with maximum cell turgor due to the nocturnally accumulated malic acid, and with the period of low cytoplasmic pH associated with malic acid movement from vacuole to cytosol. Maximum growth rates were generally only 20% of those in C3 plants and were reached at a different time of the day compared with C3 plants. The results suggest that malic acid, as a source of carbohydrates, and a determinant of turgor and cytoplasmic pH, plays a major role in the control of diel growth dynamics in CAM plants under desert conditions. The observed plasticity in phasing of growth rhythms under situations of differing water availability suggests that a complex network of factors controls the diel growth patterns in CAM plants and needs to be investigated further.

scholarly journals Cooperation mitigates diversity loss in a spatially expanding microbial population

2019 ◽  
Vol 116 (47) ◽  
pp. 23582-23587 ◽  
Author(s):  
Saurabh R. Gandhi ◽  
Kirill S. Korolev ◽  
Jeff Gore
Keyword(s):  
Genetic Drift ◽  
Founder Effect ◽  
Microbial Population ◽  
Growth Dynamics ◽  
Low Density ◽  
Drastic Reduction ◽  
Diversity Loss ◽  
Abrupt Changes ◽  
Expanding Population ◽  
Serial Founder Effect

The evolution and potentially even the survival of a spatially expanding population depends on its genetic diversity, which can decrease rapidly due to a serial founder effect. The strength of the founder effect is predicted to depend strongly on the details of the growth dynamics. Here, we probe this dependence experimentally using a single microbial species, Saccharomyces cerevisiae, expanding in multiple environments that induce varying levels of cooperativity during growth. We observe a drastic reduction in diversity during expansions when yeast grows noncooperatively on simple sugars, but almost no loss of diversity when cooperation is required to digest complex metabolites. These results are consistent with theoretical expectations: When cells grow independently from each other, the expansion proceeds as a pulled wave driven by growth at the low-density tip of the expansion front. Such populations lose diversity rapidly because of the strong genetic drift at the expansion edge. In contrast, diversity loss is substantially reduced in pushed waves that arise due to cooperative growth. In such expansions, the low-density tip of the front grows much more slowly and is often reseeded from the genetically diverse population core. Additionally, in both pulled and pushed expansions, we observe a few instances of abrupt changes in allele fractions due to rare fluctuations of the expansion front and show how to distinguish such rapid genetic drift from selective sweeps.

scholarly journals Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guiñazui

2008 ◽  
Vol 4 (3) ◽  
pp. 282-285 ◽  
Author(s):  
A Chinsamy ◽  
L Codorniú ◽  
L Chiappe
Keyword(s):  
Growth Dynamics ◽  
Growth Patterns ◽  
Growth Strategy ◽  
Filter Feeder ◽  
Definitive Evidence ◽  
Developmental Growth ◽  
Adult Body ◽  
Body Sizes ◽  
Determinate Growth ◽  
Insight Into

Life-history parameters of pterosaurs such as growth and ontogenetic development represent an enigma. This aspect of pterosaur biology has remained perplexing because few pterosaur taxa are represented by complete ontogenetic series. Of these, Pterodaustro is unique in that besides being represented by hundreds of individuals with wing spans ranging from 0.3 to 2.5 m, it includes an embryo within an egg. Here we present a comprehensive osteohistological assessment of multiple skeletal elements of a range of ontogenetic sizes of Pterodaustro , and we provide unparalleled insight into its growth dynamics. We show that, upon hatching, Pterodaustro juveniles grew rapidly for approximately 2 years until they reached approximately 53% of their mature body size, whereupon they attained sexual maturity. Thereafter, growth continued for at least another 3–4 years at comparatively slower rates until larger adult body sizes were attained. Our analysis further provides definitive evidence that Pterodaustro had a determinate growth strategy.

Voxel based analysis of recurrence dynamics in intracranial aneurysms after coiling

2017 ◽  
Vol 10 (6) ◽  
pp. 571-576 ◽  
Author(s):  
Marielle Ernst ◽  
Anika Buchholz ◽  
Romain Bourcier ◽  
Hubert Desal ◽  
Pierre-Yves Le Floch ◽  
...  
Keyword(s):  
Observation Interval ◽  
Three Dimensional ◽  
Growth Dynamics ◽  
Volumetric Analysis ◽  
Growth Patterns ◽  
Steady Increase ◽  
Residual Flow ◽  
Tof Mra ◽  
Incomplete Occlusion

BackgroundUnderstanding aneurysm growth is critical for the appropriate follow-up of patients after coil embolization and the need for retreatment. The purpose of the study was to stratify the growth dynamics of aneurysm recurrences after coiling by volumetric analysis and to determine predictive factors for aneurysm recurrences.MethodsSource images of follow-up three-dimensional time of flight MR angiography (ToF-MRA) scans were compared with the first post-interventional ToF-MRA scan and analyzed for residual flow after co-registration using ANALYZE-software. In the event of incomplete occlusion, the residual volume was segmented and calculated. Growth dynamic was determined for each aneurysm after embolization.ResultsWe analyzed 326 patients with 345 aneurysms from two centers. Each case had at least two ToF-MRA examinations after endovascular therapy. The mean observation interval was 59 months. Volumetric analysis of 1139 follow-up MRAs revealed that 218/345 aneurysms (63.2%) showed complete occlusion on initial follow-up imaging, and of these 95.0% remained stable. A steady increase in intra-aneurysmal flow was observed in 83/345 (24.1%). Less frequent observations were a steep increase (21/345; 6.1%) and a decrease (27/345; 7.8%). Independent predictors of increasing residual flow were greatest aneurysm diameter, total coil length, and incomplete occlusion.ConclusionsVolumetric analysis of registered three-dimensional ToF-MRA follow-up datasets allows the detection of different growth patterns with high precision, avoids the low inter-rater reliability, and represents a promising approach for future studies that include analysis of more complex predictors of residual flow. In cases of aneurysm recurrence after coiling, the major pattern seems to be a steady increase in intra-aneurysmal flow over several months.

scholarly journals A mixed methods study exploring the views and experiences of internationally qualified midwives in Australia: Research Protocol (Preprint)

2019 ◽  
Author(s):  
Mitra Javanmard ◽  
Mary Steen ◽  
Rachael Vernon ◽  
Megan Cooper
Keyword(s):  
Mixed Methods ◽  
South Australia ◽  
Mixed Methods Study ◽  
Second Phase ◽  
Snowball Sampling ◽  
Structured Interviews ◽  
Human Research Ethics ◽  
Sequential Mixed Methods ◽  
Transitional Experiences ◽  
Two Phases

BACKGROUND Approximately, 13% of the total Australian midwifery workforce is internationally qualified. Although they play a significant role in the Australian midwifery system, there is limited understanding of their transitional experiences. OBJECTIVE This mixed methods study aims to explore the transitional experiences and perspectives of internationally qualified midwives practising in Australia. METHODS This study uses an explanatory sequential mixed methods design incorporating two phases. The first phase of the study includes an e-survey that will be distributed to internationally qualified midwives in Australia, via the website e-bulletins of the Australian Nursing and Midwifery Federation and Australian College of Midwives. Additionally, potential respondents will be recruited via social media (Twitter, Facebook) and associated snowball sampling. At the end of the e-survey, respondents will be asked whether they are willing to take part in an interview. Data from the e-survey will be statistically analysed. The results of the e-survey and literature review will help to develop a guide for interview questions, with these interviews taking place during the second phase. A nested sample of participants will be created using the same selection criteria as for the e-survey. Semi-structured interviews will provide a deeper insight into the transitional experiences of internationally qualified midwives. Data will then be thematically analysed. RESULTS An integration of the e-survey results and interview findings will be synthesised to explore and better understand the transitional experiences of this group of midwives. The resulting data may potentially be used to formulate recommendations for future recruitment and retention practices, and to aid the Australian midwifery workforce in valuing diversity and fostering a supportive work environment. CONCLUSIONS At the time of writing this protocol, data collection had not yet commenced, however collection was subsequently completed in late 2018 and analysis is currently underway. CLINICALTRIAL This study was approved by the University of South Australia Human Research Ethics Committee (Protocol Number: 0000036397).

scholarly journals Identification of MFRP and the secreted serine proteases PRSS56 and ADAMTS19 as part of a molecular network involved in ocular growth regulation

PLoS Genetics ◽  
2021 ◽  
Vol 17 (3) ◽  
pp. e1009458
Author(s):  
Swanand Koli ◽  
Cassandre Labelle-Dumais ◽  
Yin Zhao ◽  
Seyyedhassan Paylakhi ◽  
K. Saidas Nair
Keyword(s):  
Axial Length ◽  
Growth Regulation ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Molecular Network ◽  
Molecular Response ◽  
Loss Of Function ◽  
Critical Determinant ◽  
Ocular Growth ◽  
Axial Growth

Precise regulation of ocular size is a critical determinant of normal visual acuity. Although it is generally accepted that ocular growth relies on a cascade of signaling events transmitted from the retina to the sclera, the factors and mechanism(s) involved are poorly understood. Recent studies have highlighted the importance of the retinal secreted serine protease PRSS56 and transmembrane glycoprotein MFRP, a factor predominantly expressed in the retinal pigment epithelium (RPE), in ocular size determination. Mutations in PRSS56 and MFRP constitute a major cause of nanophthalmos, a condition characterized by severe reduction in ocular axial length/extreme hyperopia. Interestingly, common variants of these genes have been implicated in myopia, a condition associated with ocular elongation. Consistent with these findings, mice with loss of function mutation in PRSS56 or MFRP exhibit a reduction in ocular axial length. However, the molecular network and cellular processes involved in PRSS56- and MFRP-mediated ocular axial growth remain elusive. Here, we show that Adamts19 expression is significantly upregulated in the retina of mice lacking either Prss56 or Mfrp. Importantly, using genetic mouse models, we demonstrate that while ADAMTS19 is not required for ocular growth during normal development, its inactivation exacerbates ocular axial length reduction in Prss56 and Mfrp mutant mice. These results suggest that the upregulation of retinal Adamts19 is part of an adaptive molecular response to counteract impaired ocular growth. Using a complementary genetic approach, we show that loss of PRSS56 or MFRP function prevents excessive ocular axial growth in a mouse model of early-onset myopia caused by a null mutation in Irbp, thus, demonstrating that PRSS56 and MFRP are also required for pathological ocular elongation. Collectively, our findings provide new insights into the molecular network involved in ocular axial growth and support a role for molecular crosstalk between the retina and RPE involved in refractive development.

Age and growth studies of Gummy Shark, Mustelus antarcticus Gunther, and School Shark, Galeorhinus galeus (Linnaeus), from Souther Australian Waters

1992 ◽  
Vol 43 (5) ◽  
pp. 1241 ◽  
Author(s):  
PL Moulton ◽  
TI Walker ◽  
SR Saddlier
Keyword(s):  
South Australia ◽  
Growth Curves ◽  
Growth Patterns ◽  
Growth Equation ◽  
Von Bertalanffy ◽  
Fishing Mortality ◽  
Male And Female ◽  
Length Data ◽  
Von Bertalanffy Growth Equation ◽  
Galeorhinus Galeus

Age-length data were derived from counting stained bands on whole vertebral centra obtained from gummy shark, Mustelus antarcticus, captured by gill-nets during 1973-76 in Bass Strait and from gummy shark and school shark, Galeorhinus galeus, captured during 1986-87 in Bass Strait and waters off South Australia. The data were fitted to the von Bertalanffy growth equation after adopting the Francis reparametrization and correcting for sampling bias caused by the selectivity effects of the gill-nets of various mesh sizes used to capture the sharks. The von Bertalanffy growth curves of male and female gummy shark were significantly different, but the growth curves of male and female school shark were not. The growth curves suggest that growth rates of male and female gummy shark in Bass Strait were lower during 1986-87 than during 1973-76 and that the growth rates of male and female gummy shark and school shark in Bass Strait during 1986-87 were lower than those in South Australia at the same time. These apparent temporal and spatial differences in growth patterns of gummy shark are explained by the 'Phenomenon of Apparent Change in Growth Rate'. It is concluded that the growth curves determined for 1986-87 are distorted by the effects of a long history of high and length-selective fishing mortality and that actual growth patterns of gummy shark are better represented by the von Bertalanffy growth equation determined for shark caught in Bass Strait during 1973-76, when fishing mortality was much lower. Verification of age estimates was attempted by comparing von Bertalanffy growth curves derived from age-length data with those derived from tag release-recapture length-increment data, but these comparisons highlight the limitations of using tag data for this purpose. Although reasonable agreement was found between such growth curves for gummy shark, it appears that school shark older than 11 years cannot be aged accurately from stained whole or sectioned vertebrae. Sectioned vertebrae from a school shark recaptured 35.7 years after being tagged and released and calculated as having an age exceeding 45 years gave estimates of only 18-20 years of age.

scholarly journals Therapeutic approach to Class II, Division 1 malocclusion with maxillary functional orthopedics

2015 ◽  
Vol 20 (4) ◽  
pp. 99-125 ◽  
Author(s):  
Aristeu Corrêa de Bittencourt Neto ◽  
Armando Yukio Saga ◽  
Ariel Adriano Reyes Pacheco ◽  
Orlando Tanaka
Keyword(s):  
Treatment Strategies ◽  
Class Ii ◽  
Growth Patterns ◽  
Mixed Dentition ◽  
Interceptive Orthodontics ◽  
Facial Esthetics ◽  
Division 1 ◽  
Two Phases ◽  
Consequent Improvement ◽  
Class Ii Division 1

INTRODUCTION: Interceptive treatment of Class II, Division 1 malocclusion is a challenge orthodontists commonly face due to the different growth patterns they come across and the different treatment strategies they have available.OBJECTIVE: To report five cases of interceptive orthodontics performed with the aid of Klammt's elastic open activator (KEOA) to treat Class II, Division 1 malocclusion.METHODS: Treatment comprehends one or two phases; and the use of functional orthopedic appliances, whenever properly recommended, is able to minimize dentoskeletal discrepancies with consequent improvement in facial esthetics during the first stage of mixed dentition. The triad of diagnosis, correct appliance manufacture and patient's compliance is imperative to allow KEOA to contribute to Class II malocclusion treatment.RESULTS: Cases reported herein showed significant improvement in skeletal, dental and profile aspects, as evinced by cephalometric analysis and clinical photographs taken before, during and after interceptive orthodontics.

Application of a 'case-building approach' to investigate the age distributions and growth dynamics of Australian sardine (Sardinops sagax) off South Australia

2007 ◽  
Vol 58 (5) ◽  
pp. 461 ◽  
Author(s):  
P. J. Rogers ◽  
T. M. Ward
Keyword(s):  
Growth Parameters ◽  
South Australia ◽  
Growth Dynamics ◽  
Percentage Error ◽  
Commercial Catch ◽  
Average Percentage ◽  
Daily Increments ◽  
Sardinops Sagax ◽  
Age Structured ◽  
Average Percentage Error

Like many pelagic fish, sardine Sardinops sagax is difficult to age by counting structures in otoliths. Of 12968 whole otoliths analysed in the present study, <25% could be counted with accuracies of greater than ±1 zone. Estimates of average percentage error (APE) were high (11.37%). We used a ‘case building approach’ to corroborate a method for estimating age. Regressions of otolith weight–age from otoliths with high readabilities were used to estimate the age of fish with lower or unreadable otoliths. Growth rates determined from daily increments ranged from 0.36 to 0.75 mm day–1 for larvae and from 0.22 to 0.47 mm day–1 for juveniles. Estimates of von Bertalanffy growth coefficients were k = 0.32–1.07 year–1 and L∞ = 166.96–195.68 mm. Growth parameters estimated during the present study support previous assertions that levels of pelagic production in South Australian (SA) waters lie between those recorded in the predominantly oligotrophic waters off Western Australia (WA) and the productive waters off southern California and South Africa. Disparities in the age distributions of inshore and offshore samples suggest that age data from commercial catch samples may not be representative of the population. This finding has implications for the use of age-structured models to assess of stocks of S. sagax and other small pelagic fishes.

scholarly journals Persistent growth slowdowns in fast-growing middle-income economies

2017 ◽  
Vol 67 (s1) ◽  
pp. 97-111 ◽  
Author(s):  
Krisztina Sőreg
Keyword(s):  
Global Financial Crisis ◽  
Raw Materials ◽  
Commodity Prices ◽  
Growth Dynamics ◽  
Commodity Price ◽  
Growth Patterns ◽  
Growth Data ◽  
Middle Income ◽  
Fast Growing ◽  
Export Structure

From the second half of the 20th century, a set of emerging economies have undergone a remarkable developing path. During the first years of the global financial crisis of 2007–2008, Brazil, Russia, India, China, and South Africa (BRICS) were only slightly affected by its negative impacts. However, after 2013, a considerable growth slowdown period has evolved in these countries with the exception of the Indian economy. In the current study, we examine whether the growth dynamics of the BRICS economies shows significant correlation with the fluctuation of commodity prices, especially in the case of raw materials. Besides applying a cross correlation model on the quarterly commodity price indices and real GDP growth data, the research also focuses on the export structure of the selected fast-growing countries. As a closing element of our paper, a brief analysis is carried out regarding the correlations of growth patterns within the BRICS economies.

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