Dorsal-fin spine growth of Heterodontus portusjacksoni: a general model that applies to dorsal-fin spines of chondrichthyans?

2008 ◽  
Vol 65 (1) ◽  
pp. 74-82 ◽  
Author(s):  
Javier Tovar-Ávila ◽  
Christopher Izzo ◽  
Terence I Walker ◽  
J Matias Braccini ◽  
Robert W Day
Keyword(s):  
Growth Zone ◽  
Layer Growth ◽  
Spine Length ◽  
External Edge ◽  
Dorsal Fin ◽  
Growth Increments ◽  
Second Growth ◽  
Growth Bands ◽  
Growth Zones ◽  
Prospective Model

A prospective model of dorsal-fin spine growth in chondrichthyans is devised by studying the growth of spines from captive and wild Heterodontus portusjacksoni injected with several fluorochromes. Evidence was found for only two dentine layers in the spine trunk of H. portusjacksoni, contrasting with conjectures about the presence of a third middle dentine layer in some squalids. The spines have three simultaneous growth zones. The first growth zone is along the internal edge of the inner trunk dentine layer, where growth bands are deposited towards the centre (centripetally), increasing spine length and width by pressure against the cartilage rod. The second growth zone is along the external edge of the outer trunk dentine layer at the spine base, where growth bands are deposited in an opposite direction to the centre (centrifugally), increasing spine width. A third growth zone at the base of the cap enables downward expansion over the trunk. The model of concentric cones describes correctly the inner dentine layer growth pattern, whereas the outer dentine layer growth increments appear to be related to the external bands on the surface of the trunk. Growth increments from the three growth zones of the spine are all potentially useful for age estimation.

Age structure and life cycles of the Argentine shortfin squid Illex argentinus (Cephalopoda: Ommastrephidae) in southern Brazil

2012 ◽  
Vol 93 (2) ◽  
pp. 557-565 ◽  
Author(s):  
R. Schwarz ◽  
J.A.A. Perez
Keyword(s):  
Life Cycle ◽  
Age Structure ◽  
Life Cycles ◽  
Southern Brazil ◽  
Trawl Fishery ◽  
Growth Increments ◽  
Wide Range ◽  
Growth Zones ◽  
Illex Argentinus ◽  
Post Spawning

Age structure and hatchling dates of the squid Illex argentinus collected by bottom-trawl fishery in southern Brazilian waters were assessed by the analysis of statolith growth increments. Catches occurred between 2001 and 2002, from 23° to 32°S at depths of 100–700 m. Squid from juvenile to post-spawning stages were collected year round, with age estimated from 98 to 320 days and mantle lengths ranging from 112 to 376 mm. Duration of life cycle events based on statolith growth zones revealed that squids can spend about 14% of their lifespan as paralarva (~30 days), 70% as juvenile (~130 days), leaving maturity and spawning condition to the terminal 10–20% (~30–60 days). The results suggest that, unlike estimates available for Patagonian populations, a general 0.5 year lifespan is predicted for I. argentinus off Brazil. The wide range of size-at-ages implied that catches of shortfin squid off southern Brazil probably include squid hatched throughout the year. Mature and spawning squid caught in summer months hatched in winter and spring, while winter catches revealed mature-spawning individuals hatched both in summer/autumn (~6 months of age) and winter/spring periods (~10–11 months of age). It has been argued that such groups may combine both squid resident of Brazilian outer shelf and slope (22°–34°S) with a six months' lifespan and migrating squid originated from the northern Patagonian shelf (~42°S) with 10–11 months' lifespan.

Light-dependent seedling survival and growth of four tree species in Costa Rican second-growth rain forests

2005 ◽  
Vol 21 (4) ◽  
pp. 383-395 ◽  
Author(s):  
Silvia Iriarte Vivar Balderrama ◽  
Robin L. Chazdon
Keyword(s):  
Tree Species ◽  
Seedling Survival ◽  
Light Availability ◽  
Light Transmittance ◽  
Growth Responses ◽  
Low Light ◽  
Growth Increments ◽  
Light Gradient ◽  
Second Growth ◽  
Survival And Growth

The dependence of tree seedling survival and growth on light availability was evaluated over 15 mo in three second-growth, wet forest stands (15–18 y old) in north-eastern Costa Rica. Seedlings of four canopy tree species (Dipteryx panamensis, Hyeronima alchorneoides, Virola koschnyi and Vochysia guatemalensis) were planted into four canopy treatments in three replicated stands and in a pasture site, spanning a nearly complete gradient of light availability. Survival and growth of all species increased in response to increasing light availability, but species differed in survival in shaded microsites (6–20% light transmittance) and in growth increments per light increase. Hyeronima showed the highest mortality at low light levels and the highest relative height growth increase per light increase. In contrast, Virola showed high survival at low and moderate light, but showed the lowest leaf area and above-ground biomass per light increase among all species. Dipteryx and Vochysia maintained relatively high rates of survival and growth across the entire light gradient. Hyeronima and Virola showed trade-offs between growth and survival responses to light, unlike Dipteryx and Vochysia. Differences among species in seedling survival at low light may be determined by a variety of physiological and morphological traits that may or may not be mechanistically linked to growth responses.

Geographic Variation in the Brook Stickleback, Culaea inconstans, and Notes on Nomenclature and Distribution

1969 ◽  
Vol 26 (9) ◽  
pp. 2431-2447 ◽  
Author(s):  
Joseph S. Nelson
Keyword(s):  
Geographic Variation ◽  
Northwestern Part ◽  
Clinal Variation ◽  
Body Depth ◽  
Spine Length ◽  
Culaea Inconstans ◽  
Dorsal Fin ◽  
Fin Rays ◽  
Historical Origin ◽  
Brook Stickleback

Clinal variation in dorsal and pelvic spine lengths was observed in the brook stickleback, Culaea inconstans, in an examination of 1366 specimens from 62 localities. Mean spine length was longest in the Wisconsin to Ohio area and generally decreased to the west, north, and east of this area. Shortest spines were observed in the northwestern part of the range of the species. A population in New Mexico, believed to be relict, was highly variable, but most specimens had long spines. Pelvic spines, and the supporting skeleton, were absent in most specimens from five localities in Alberta. Pelvic skeleton size and body depth were generally greatest in the area east of Wisconsin and least in the northwestern part of the range. Although C. inconstans is generally described as being naked, a series of about 30–36 small bony scutes was found along the lateral line in all populations examined. No marked geographic variation was observed in number of pectoral rays, caudal rays, soft dorsal-fin rays, soft anal-fin rays, gill rakers, scutes, or vertebrae. The nomenclature and distribution of C. inconstans are reviewed. The historical origin of clinal variation in spine length is discussed.

Assessing growth band counts from vertebrae and dorsal-fin spines for ageing sharks: comparison of four methods applied to Heterodontus portusjacksoni

2009 ◽  
Vol 60 (9) ◽  
pp. 898 ◽  
Author(s):  
Javier Tovar-Ávila ◽  
Christopher Izzo ◽  
Terence I. Walker ◽  
J. Matías Braccini ◽  
Robert W. Day
Keyword(s):  
Shark Species ◽  
Systematic Bias ◽  
Age Validation ◽  
Growth Band ◽  
Dorsal Fin ◽  
Growth Bands ◽  
Visible Growth ◽  
Port Jackson ◽  
First Time ◽  
Fin Spines

Four methods for counting growth bands using vertebrae and dorsal-fin spines of the Port Jackson shark, Heterodontus portusjacksoni, are compared. Both calcified structures presented observable growth bands, allowing cross comparison among structures for the first time in a shark species. Whole and sectioned vertebrae and dorsal fin-spines possess highly visible growth bands and intra-reader band counts resulted in similar precision indices with little systematic bias. However, inter-reader growth band count plots showed possible biases in counts from sectioned vertebrae and sectioned dorsal-fin spines. Sectioned vertebrae and whole and sectioned dorsal-fin spines produced similar growth band counts, whereas whole vertebrae produced significantly lower counts. The similar readability, precision indices, growth band counts and apparent absence of biases between counts for a single reader would indicate that sectioned vertebrae and whole and sectioned dorsal-fin spines are both potentially useful and acceptable methods for band counting. However, inter-reader comparisons are necessary to avoid acceptance of biased estimations, resulting in over- or under-estimations of age. Validation for all age classes is essential to determining accurate age estimations for this and other species.

scholarly journals Mental Resilience of Medical Practitioners in Singapore during COVID-19: Survey Results from a Webinar Course on Resilience

2021 ◽  
Vol 18 (18) ◽  
pp. 9801
Author(s):  
Cheng Hong Charity Low ◽  
Tze Jui Goh ◽  
Yiong Huak Chan ◽  
Daniel Shuen Sheng Fung ◽  
Pak Yean Cheong
Keyword(s):  
General Practitioners ◽  
Family Physicians ◽  
Growth Zone ◽  
Front Line ◽  
Effective Response ◽  
Medical Practitioners ◽  
Growth Zones ◽  
Survey Results ◽  
Risk Of Exposure ◽  
Mental Resilience

Front-line doctors are at high risk of exposure to COVID-19. The mental resilience of general practitioners and their areas of concerns and support required are important during this COVID-19 period. A total of 403 general practitioners attending a webinar on resiliency, hosted by the College of Family Physicians, Singapore, participated in the survey anonymously. Participants provided responses to questions relating to COVID-19 in the domains of Family and friends, Myself, Practice, and Community. Responses are categorized into LEARNING, FEAR, and GROWTH zones. The majority of the doctors reported to be in the GROWTH zone in relation to Family and friends (39%) and Myself (38%) as compared to Practice and Community, aOR = 4.5 (95% CI 3.4 to 5.9), p < 0.001. 34% of the participants reported being in the FEAR zone in relation to Family and friends, aOR = 8.0 (95% CI = 5.6 to 11.2), p < 0.001; at least 81% reported being in the LEARNING zone in relation to Practice and Community, aOR = 7.5 (95% CI = 5.8 to 9.6), p < 0.001, compared to other domains. Supporting and protecting the doctors is important in strategic planning and management of the current pandemic and building preparedness and an effective response towards future crises.

scholarly journals A New Record of the Pseudolaguvia nubila (Siluriformes: Erethistidae) from Baandhkhola (Stream) in Central Nepal

2017 ◽  
Vol 5 (4) ◽  
pp. 434-441
Author(s):  
Asha Rayamajhi ◽  
M. Arunachalam
Keyword(s):  
New Record ◽  
Outer Edge ◽  
Pectoral Fin ◽  
Body Depth ◽  
Spine Length ◽  
Dorsal Fin ◽  
Central Nepal ◽  
The Family ◽  
Fin Length

In this study, we describe a miniature sisorid catfish of the family Erethistidae, as a new distributional record of Pseudolaguvia nubila from the Baandhkhola (stream), a tributary of Narayani River inCentral Nepal. Pseudolaguvia nubila shows its distribution to Nepal is distinguished from its congeners by combination of characters, such as- two broad and distinct yellowish vertical bands at the origin of dorsal fin and anal fin, smooth outer edge of the dorsal fin spine, dorsal fin spine length 13.23-17.60 % SL, pectoral fin length 24.89-26.27 % SL, pectoral fin spine length 18.39-19.48 % SL and body depth at anus 17.22-18.69 % SL.Int. J. Appl. Sci. Biotechnol. Vol 5(4): 434-441

Inter-regional cluster formation based on the concept of spatial development

2020 ◽  
Vol 18 (4) ◽  
pp. 688-708
Author(s):  
L.I. Pronyaeva ◽  
A.V. Pavlova ◽  
O.A. Fedotenkova
Keyword(s):  
Economic Growth ◽  
Cluster Formation ◽  
Growth Zone ◽  
Inclusive Development ◽  
Expert Assessment ◽  
Regional Clusters ◽  
Regional Cluster ◽  
Growth Zones ◽  
Smart Specialization ◽  
Forming Methods

Subject. This article discusses the organizational and economic processes, and conditions for the formation and development of inter-regional clusters. Objectives. The article aims to clarify ideas and develop recommendations to assess the conditions and possibilities of inter-regional cluster forming. Methods. For the study, we used statistical analysis, graphical, and expert assessment methods, and a literature review. Results. The article proposes certain phases and an algorithm to form inter-regional clusters as potential economic growth zones of the regions. Conclusions and Relevance. The inter-regional cluster formation and development should be based on the economic-growth-zone theory and models based on the principles of inclusive development and smart specialization. The results of the study may be a basis to develop a strategy for inter-regional clusters operating at the level of the country's macro-regions.

Refined bomb radiocarbon dating of two iconic fishes of the Great Barrier Reef

2015 ◽  
Vol 66 (4) ◽  
pp. 305 ◽  
Author(s):  
Allen H. Andrews ◽  
John H. Choat ◽  
Richard J. Hamilton ◽  
Edward E. DeMartini
Keyword(s):  
Great Barrier Reef ◽  
Radiocarbon Dating ◽  
Growth Zone ◽  
Barrier Reef ◽  
Hermatypic Coral ◽  
Advanced Technologies ◽  
Bomb Radiocarbon ◽  
Growth Zones ◽  
Bolbometopon Muricatum ◽  
Age Estimates

Refinements to the methodology of bomb radiocarbon dating made it possible to validate age estimates of the humphead wrasse (Cheilinus undulatus) and bumphead parrotfish (Bolbometopon muricatum). Age for these species has been estimated from presumed annual growth zones in otoliths at ~30 and ~40 years respectively. The validity of these estimates was tested using bomb radiocarbon dating on the small and fragile otoliths of these species, and provided an opportunity to refine the method using advanced technologies. A regional Δ14C reference record from hermatypic coral cores from the Great Barrier Reef was assembled and Δ14C measurements from extracted otolith cores of adult otoliths were successful. Validated ages supported the accuracy of growth zone derived ages using sectioned sagittal otoliths.

Tungsten-bearing rutile from the Kori Kollo gold mine, Bolivia

1998 ◽  
Vol 62 (3) ◽  
pp. 421-429 ◽  
Author(s):  
C. M. Rice ◽  
K. E. Darke ◽  
J. W. Still ◽  
E. E. Lachowski
Keyword(s):  
Hydrothermal System ◽  
Hydrothermal Fluids ◽  
Gold Mine ◽  
Backscatter Electron ◽  
Charge Balance ◽  
Sector Zoning ◽  
Oxide Zone ◽  
Growth Bands ◽  
Growth Zones ◽  
Double Substitution

AbstractW-bearing rutile formed during alteration of jarosite by resurgent hydrothermal fluids in the oxide zone of the Kori Kollo gold deposit. The rutile shows sector zoning in basal sections and well developed multiple growth zones, both defined in backscatter electron images by variations in the W content. The maximum WO3 content is 5.3 wt.% and W substitutes for Ti with double substitution of Fe to maintain charge balance. The causes of multiple growth bands are considered to be changes in externally controlled variables occurring in a shallow hydrothermal system. Whereas Ti is probably leached from biotite in dacitic rocks, the W is introduced by hydrothermal fluids.

Observations on the formation, development, and structure of the tuber of Testudinaria elephantipes, and on the origin of the vegetative shoot

1935 ◽  
Vol 49 (332) ◽  
pp. 593-610 ◽  
Author(s):  
E. N. Sparshott
Keyword(s):  
Vascular Tissue ◽  
Developmental Stages ◽  
Adventitious Shoots ◽  
Secondary Growth ◽  
Longitudinal Section ◽  
Growth Zone ◽  
Vegetative Shoot ◽  
Growth Rings ◽  
Growth Zones ◽  
Medullary Parenchyma

Summary The young plants used for these observations were grown from seed collected in the Southern Karroo. The tuber of Testudinaria elephantipes is at first small, white, and spherical. Later it turns brown and develops a flattened or concave base and a thin continuous periderm. In the older, massive, semi-globular condition the tuber has a thick, deeply fissured, corky crust. Towards the base of the tuber the cork forms a thinner layer, broken only by the protrusion of roots. Various developmental stages are figured. There is no cork over a small area at the apex of the tuber. The growing point of the vegetative shoot is in this region, and is enclosed within a number of persistent scale leaves. The seed contains a small embryo embedded in considerable endosperm. There is no suggestion of tuberisation in the embryo. The development of the seedling is described and figured. A longitudinal section suggests that the plumular axis consists at first of little more than a stem apex and one leaf. Lack of opportunity for translocation of food synthesised is probably the cause of tuberisation. An explanation of the lack of symmetry is suggested. Tuberisation is not due to fungal infection. The anatomy of seedlings at different stages of development is described. The initial thickening of the hypocotyl results partly from cell division and partly from hypertrophy of the cortical parenchyma cells. Tuberisation is finally due to secondary growth originating in the pericycle. The early development of the cork crust and the growth zone is described. The structure of a three-year old tuber is dealt with in some detail. In general, the growth zone is hemispherical. Beneath the apex and just above the base no continuous meristem appears, though local growth zones may be found over the base. Vascular strands and medullary parenchyma are cut off towards the inside of the meristem, and secondary parenchyma towards the outside. The vascular tissue forms a small flat network under the apex and a larger network over the base, and these plates are connected by a complex system of anastomosing vascular strands running down the side of the tuber towards the inside of the growth zone. These vascular systems form growth rings. The bulk of the tissue cut off from the growth zone is parenchymatous. Fissures abutting on the medullary rays appear in the cork. The exposed parenchyma within the cork becomes suberised and a new band of cork is formed. Over the base of the tuber the original cork layer persists. An explanation is given for the origin of adventitious shoots. The sympodial origin of the seasonal vegetative shoots formed at the apex of the tuber is described and figured. The tuber is held to consist of a secondarily thickened hypocotyl and a very short epicotyl.

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