Stalk Morphology Research Articles

A Nomogram of MRI Features to Assess Muscle Invasion in VI-RADS 2 Tumors With Stalk.

Vesical Imaging-Reporting and Data System (VI-RADS) is widely used to assess the muscle-invasive status of bladder cancer. However, the current classification efficacy of VI-RASD 2 tumors of stalk is unsatisfactory. To develop a nomogram to assess muscle-invasive bladder cancer (MIBC) in VI-RADS 2 tumors with stalk. Retrospective. A total of 186 patients (age: 67.8 ± 12.7 years) with 15.1% females, divided randomly into a training cohort (N = 130) and validation cohort (N = 56). 3-T, T2-weighted imaging (turbo spin-echo), diffusion-weighted imaging (breathing-free spin-echo), and dynamic contrast-enhanced imaging (gradient-echo). Twenty-one MRI features of tumors and stalks were developed from training cohort. The mean apparent diffusion coefficient (ADC) values of the tumor, stalk, and psoas muscles were calculated from the three circular regions of interest. The normalized T . The normalized ST . Three readers assessed the morphology of tumors and stalks. The final features of nomogram were selected by univariable logistic and the least absolute shrinkage and selection operator (LASSO) regression. The performance of the nomogram was assessed by the receiver operating characteristic (ROC) curve, calibration, and decision curve analysis. In VI-RADS 2 tumors with stalk, tumor size over 3 cm, increased stalk width, stalk morphology, decreased normalized T value, and increased normalized ST value were selected as the risk factors for MIBC. The AUC, accuracy, sensitivity, and specificity of the nomogram to assess MIBC were 0.969 (95% CI: 0.941-0.997), 92.3%, 94.1%, and 92.0% in training cohort and 0.940 (95% CI: 0.859-1.000), 89.3%, 75.0%, and 91.7% in validation cohort. This study constructed a nomogram for preoperative assessment of MIBC and modifying the current VI-RADS. 3 TECHNICAL EFFICACY: Stage 2.

Pituitary Stalk Morphology as a Predictor of New-Onset Adrenocortical Insufficiency and Arginine Vasopressin Deficiency after Transsphenoidal Resections of Pituitary Macroadenomas: A Retrospective Single-Center Study with a Focus on iMRI.

A new-onset adrenocortical insufficiency (NAI) is the most critical postoperative endocrinological complication after transsphenoidal surgery for macroadenomas. Because of increased mortality risk, arginine vasopressin deficiency (AVP-D) is also a relevant postoperative complication. This study aimed to identify easy-to-acquire magnet resonance imaging (MRI) aspects of the pituitary stalk to predict these insufficiencies after transsphenoidal surgery. Pituitary stalk morphology was reviewed intraoperatively and three months postoperatively in the MRIs of 48 transsphenoidal surgeries for macroadenomas. NAI was validated in endocrinological follow-up controls 10-14 months post-surgery. Intraoperative pituitary stalk diameters were 0.5 mm larger in patients who developed NAI and AVP-D. The odds ratio was 29 for NAI and 6 for AVP-D in binary regression analysis. A value of 2.9 mm was identified as the optimal cut-off for the minimal pituitary stalk diameter regarding NAI, with a high specificity of 89%. There was no difference in pituitary stalk diameter regarding these insufficiencies three months post-surgery. We identified an increased pituitary stalk diameter in intraoperative MRIs as a predictive factor of NAI and AVP-D after transsphenoidal surgery. These findings might improve the early detection of NAI and, thus, optimal management. However, validating these retrospective findings in prospective studies is obligatory.

A novel in-situ quantitative profiling approach for visualizing changes in lignin and cellulose by stained micrographs

There is a strong need for low-cost lignocellulosic composition simultaneous localization methodologies to benefit deeper understandings of crop stalk morphology. This study developed a robust quantitative safranin O-fast green staining-based optical microscopy imaging methodology for in-situ simultaneously generating digital profiles of lignin and cellulose in stalk tissues. Foreground extraction and dye residue removal of stained images were adapted. The ratios of normalized red (R), green (G), and blue (B) channel signal intensity, R/B and G/B, were defined as quantitative indicators of lignin and cellulose, respectively. The method was validated on model rice with known bioinformatics, and the results were consistent with those of fluorescence microscopy and immunogold labeling methods. The high-definition spatial in-situ simultaneous profiles of lignin and cellulose in alkali-treated maize stalk tissues and their variations were visualized. This low-cost, cell-scale method is expected to contribute to new discoveries in many areas of biomass refining and plant science.

Maize stalk stiffness and strength are primarily determined by morphological factors

The maize (Zea mays) stem is a biological structure that must balance both biotic and structural load bearing duties. These competing requirements are particularly relevant in the design of new bioenergy crops. Although increased stem digestibility is typically associated with a lower structural strength and higher propensity for lodging, with the right balance between structural and biological activities it may be possible to design crops that are high-yielding and have digestible biomass. This study investigates the hypothesis that geometric factors are much more influential in determining structural strength than tissue properties. To study these influences, both physical and in silico experiments were used. First, maize stems were tested in three-point bending. Specimen-specific finite element models were created based on x-ray computed tomography scans. Models were validated by comparison with experimental data. Sensitivity analyses were used to assess the influence of structural parameters such as geometric and material properties. As hypothesized, geometry was found to have a much stronger influence on structural stability than material properties. This information reinforces the notion that deficiencies in tissue strength could be offset by manipulation of stalk morphology, thus allowing the creation of stalks which are both resilient and digestible.

Key indicators affecting maize stalk lodging resistance of different growth periods under different sowing dates

The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields. Here, we established five different sowing dates to create different conditions for maize growth. We evaluated the effects of the different growth conditions on lodging resistance by determining stalk morphology, moisture content, mechanical strength and dry matter, and the relationship between stalk breaking force and these indicators during the silking stage (R1), milk stage (R3), physiological maturity stage (R6), and 20 days after R6. Plant height at R1 positively affected stalk breaking force. At R3, the coefficient of ear height and the dry weight per unit length of basal internodes were key indicators of stalk lodging resistance. At R6, the key indicators were the coefficient of the center of gravity height and plant fresh weight. After R6, the key indicator was the coefficient of the center of gravity height. The crushing strength of the fourth internode correlated significantly and positively with the stalk breaking force from R1 to R6, which indicates that crushing strength is a reliable indicator of stalk mechanical strength. These results suggest that high stalk strength and low ear height benefit lodging resistance prior to R6. During and after R6, the coefficient of the center of gravity height and the mechanical strength of basal internodes can be used to evaluate plant lodging resistance and the appropriate time for harvesting in fields with a high lodging risk.

Diagnostic performance of diffusion-weighted MR imaging at 3.0T in predicting muscle invasion in urinary bladder cancer: utility of evaluating the morphology of the reactive tumor stalk.

To evaluate the diagnostic performance of stalk morphology on diffusion-weighted imaging (DWI) in comparison with conventional MRI in predicting muscle invasion in urinary bladder cancer. The study was prospective and approved by the institutional ethics committee. A written informed consent was obtained from all the patients. The study included 56 patients who presented with bladder mass between January 2014 and November 2015. After excluding 16 patients, 40 patients with 92 tumors were assessed. All the 40 patients underwent MRI at 3.0 Tesla (Achieva, Philips) inclusive of DWI (b0, 500, 1000 and 1500). Two radiologists evaluated the images independently, and disparities were resolved through consensus. For predicting muscle invasion on T2-weighted images, tumor morphology (papillary versus non-papillary), distensibility of the underlying bladder wall, and perivesical fat infiltration were evaluated. On DWI, the criterion used in a previous study (Takeuchi et al.) was used along with tumor stalk morphology. Findings were compared with histopathology using Pearson's χ2 test, and diagnostic performance indices were calculated. All the evaluated features were present with significantly higher frequency in muscle-invasive tumors (p<0.001). The finding of absent or distorted stalk on DWI had the highest sensitivity (87.5%) and specificity (97.6%). Conventional imaging features of non-papillary stalk morphology, restricted distension of underlying bladder wall, perivesical fat infiltration, as well as the previous DWI criterion were less sensitive (56.3%, 68.8%, 56.3% and 56.3%, respectively) in predicting muscle invasion. Assessment of the morphology of the reactive tumor stalk on DWI has better diagnostic performance in predicting muscle invasion than conventional MRI.

New species of the Genus Haliclona (Haplosclerida: Chalinidae) from Korea.

Two new marine sponges, Haliclona ieoensis sp. nov. and Haliclona sumenyoensis sp. nov. from the south Korea are described. Morphologically distinct from each other, both species are assigned to the genus Haliclona subgenus Haliclona. Haliclona ieoensis sp. nov. individuals are thickly encrusting to massive, beige colour and have small oscules flush on surface. Haliclona sumenyoesis sp. nov. individuals have a cylindrical tube with flexible stalk morphology, ivory colour, and large oscules. The description of these two new species brings the species of Haliclona (Haliclona) in Korea to five.

Prediction of BRAF mutation status of craniopharyngioma using magnetic resonance imaging features.

OBJECTIVE Treatment with a BRAF mutation inhibitor might shrink otherwise refractory craniopharyngiomas and is a promising preoperative treatment to facilitate tumor resection. The aim of this study was to investigate the noninvasive diagnosis of BRAF-mutated craniopharyngiomas based on MRI characteristics. METHODS Fifty-two patients with pathologically diagnosed craniopharyngioma were included in this study. Polymerase chain reaction was performed on tumor tissue specimens to detect BRAF and CTNNB1 mutations. MRI manifestations-including tumor location, size, shape, and composition; signal intensity of cysts; enhancement pattern; pituitary stalk morphology; and encasement of the internal carotid artery-were analyzed by 2 neuroradiologists blinded to patient identity and clinical characteristics, including BRAF mutation status. Results were compared between the BRAF-mutated and wild-type (WT) groups. Characteristics that were significantly more prevalent (p < 0.05) in the BRAF-mutated craniopharyngiomas were defined as diagnostic features. The minimum number of diagnostic features needed to make a diagnosis was determined by analyzing the receiver operating characteristic (ROC) curve. RESULTS Eight of the 52 patients had BRAF-mutated craniopharyngiomas, and the remaining 44 had BRAF WT tumors. The clinical characteristics did not differ significantly between the 2 groups. Interobserver agreement for MRI data analysis was relatively reliable, with values of Cohen κ ranging from 0.65 to 0.97 (p < 0.001). A comparison of findings in the 2 patient groups showed that BRAF-mutated craniopharyngiomas tended to be suprasellar (p < 0.001), spherical (p = 0.005), predominantly solid (p = 0.003), and homogeneously enhancing (p < 0.001), and that patients with these tumors tended to have a thickened pituitary stalk (p = 0.014). When at least 3 of these 5 features were present, a tumor might be identified as BRAF mutated with a sensitivity of 1.00 and a specificity of 0.91. The area under the ROC curve for the sum of all 5 diagnostic criteria was 0.989 (p < 0.001). CONCLUSIONS The BRAF mutation status of craniopharyngiomas might be predicted using certain MRI features with relatively high sensitivity and specificity, thus offering potential guidance for the preoperative administration of BRAF mutation inhibitors.

A Reanalysis of Relationships Among Calypsoinae (Orchidaceae: Epidendroideae): Floral and Vegetative Evolution and the Placement of Yoania

Calypsoinae are a small, largely temperate subtribe that are diverse with respect to trophic strategy (many species have an unusual winter leaf and several are leafless) and pollinium stalk morphology. Here we sought to re-evaluate the placement of Yoania and recently proposed genera and to examine trophic strategy, pollinium stalk type, and geographic distribution in a phylogenetic context. We analyzed ITS and matK sequences from all accepted genera using maximum likelihood and parsimony on individual and combined data sets. The only supported disagreement among trees was between the combined ML and parsimony analyses for the placement of Dactylostalix and Ephippianthus; the trees from one analysis reflected the nuclear pattern, while the other resembled the plastid pattern. A group of genera related to Calypso and a group related to Corallorhiza were resolved. Yoania is closely related to Calypso; the recently proposed Yunorchis is a species of Yoania, while Didiciea is part of Tipularia. Examining leaf morphology on the tree revealed two originations of the winter leaf morphology and four losses of leaves (and shifts to mycoheterotrophy). Pollinium stalks evolved in three directions, two of which resulted in epidermally-derived stalks (tegulae) and one that comprises the entire rostellum (a hamulus). Biogeographic analysis suggests a New World origin for the subtribe, with two major shifts to the Old World and one shift back to the New World.

Maize Stalk Lodging: Morphological Determinants of Stalk Strength

An incomplete understanding of stalk strength and stalk lodging impedes efforts to improve maize (Zea mays L.) production. To develop a more complete understanding of stalk strength, the current study examined the effect of stalk morphology on stalk bending strength. A detailed geometric analysis was conducted on five varieties of dent corn sown at five planting densities in two replicates at each of two locations near Greenville, IA, in 2013. Stalks were imaged using high‐resolution X‐ray computed tomography, and morphological features of the stalk were quantified using customized computer code. After scanning, stalks were subjected to mechanical tests to determine stalk bending strength and rind penetration resistance. The section modulus of the stalk (a morphological quantity derived from engineering beam theory) was found to be highly predictive of stalk strength, and its predictions appear to be largely unaffected by common confounding factors such as hybrid and planting density. By assuming the stalk cross section to be a hollow ellipse, the section modulus of the stalk can be estimated using measurements of stalk diameter and rind thickness (which does not require computerized tomography scanning). The elliptical section modulus is highly predictive of stalk strength, does not appear to be confounded by experimental variables, and can be obtained using a pair of calipers. Thus, it demonstrates potential as a selective breeding index to improve lodging resistance. In the current study, the elliptical section modulus predicted stalk strength with four times the accuracy of rind penetration resistance (a more common method used in breeding studies).

Selective single-stage xylan-to-xylose hydrolysis and its effect on enzymatic digestibility of energy crops giant reed and cardoon for bioethanol production

The low temperature dilute sulfuric acid hydrolysis of two potential European energy crops − giant reed and cardoon have been studied for separation and valorization of total hemicellulosic carbohydrates prior to fractionation of cellulose and lignin, viewing as entry point to integrated biorefining scheme. The combined severity factor (CSF) was used to assess, on comparative basis, the selectivity and efficiency of xylan-to-xylose conversion and its effect on enzymatic digestibility of residual cellulose. The reliable quantitative correlations have been established for the first time between the CSF and the main outputs of acid and enzymatic hydrolysis. Xylose recovery of ca. 94% and 86% (as max.) was achieved at CSF 1.90 and 1.97, respectively for giant reed and cardoon, with formation of ca. 2.4% glucose, 1.1% furfural, 0.5% HMF and 3.2% acetic acid. Under these CSF levels, the enzymatic digestibility of residual cellulose was improved only up to 0.75 and 0.80 (75% and 80% total Glc recovery, respectively for giant reed and cardoon), vs. 0.09 and 0.19 for untreated biomass. The digestibility was further improved to 0.93 and 0.98 with increase in hydrolysis severity up to CSF 2.44, while substantial loss of xylose (ca. 40%) and furans formation (ca. 5% furfural) was found. The essential effect of cardoon stalk morphology on uniformity and modeling of biorefining separation processes was noted.

Corn Stalk Lodging: A Forensic Engineering Approach Provides Insights into Failure Patterns and Mechanisms

ABSTRACTStalk lodging is essentially a structural failure. It was therefore hypothesized that application of structural and forensic engineering principles would provide novel insights into the problem of late‐season stalk lodging of maize (Zea mays L.). This study presents results from a structural engineering failure analysis of corn stalk lodging, involving detailed inspection and measurements of lodged stalks and a multidimensional imaging study to assess stalk architecture based on structural engineering principles. This work involved in‐field observation of &gt;20 varieties of lodged corn stalk in eight international locations and detailed geometric analysis of four varieties. Analysis of collected data revealed very strong, yet previously unreported, patterns in corn stalk lodging. Corn stalks predominantly fail (break) by creasing, fall in the direction of the minor diameter of the cross section, and break within 4 cm of a node. These failure patterns, across a broad sampling of varieties and environments, suggest a consistent weakness in maize stalk architecture, indicating that a common solution might be identified to strengthen maize stalks. Structural engineering analysis of stalk architecture and morphology revealed that several geometric stress concentrators (features known from engineering theory to increase local stresses) occur in the predominant failure region of corn stalk. Identified stress concentrators include surface irregularities, sharp changes in diameter, and voids occurring in the stalk pith. Each of these stalk features persist across different international locations, environmental conditions, and hybrid varieties. These findings support the use of new selective breeding approaches that focus on stalk morphology and structural engineering analysis of corn stalk architecture to develop lodging resistant varieties of maize.

Morphology of biogenic iron oxides records microbial physiology and environmental conditions: toward interpreting iron microfossils

Despite the abundance of Fe and its significance in Earth history, there are no established robust biosignatures for Fe(II)-oxidizing micro-organisms. This limits our ability to piece together the history of Fe biogeochemical cycling and, in particular, to determine whether Fe(II)-oxidizers played a role in depositing ancient iron formations. A promising candidate for Fe(II)-oxidizer biosignatures is the distinctive morphology and texture of extracellular Fe(III)-oxyhydroxide stalks produced by mat-forming microaerophilic Fe(II)-oxidizing micro-organisms. To establish the stalk morphology as a biosignature, morphologic parameters must be quantified and linked to the microaerophilic Fe(II)-oxidizing metabolism and environmental conditions. Toward this end, we studied an extant model organism, the marine stalk-forming Fe(II)-oxidizing bacterium, Mariprofundus ferrooxydans PV-1. We grew cultures in flat glass microslide chambers, with FeS substrate, creating opposing oxygen/Fe(II) concentration gradients. We used solid-state voltammetric microelectrodes to measure chemical gradients in situ while using light microscopy to image microbial growth, motility, and mineral formation. In low-oxygen (2.7-28μm) zones of redox gradients, the bacteria converge into a narrow (100μm-1mm) growth band. As cells oxidize Fe(II), they deposit Fe(III)-oxyhydroxide stalks in this band; the stalks orient directionally, elongating toward higher oxygen concentrations. M.ferrooxydans stalks display a narrow range of widths and uniquely biogenic branching patterns, which result from cell division. Together with filament composition, these features (width, branching, and directional orientation) form a physical record unique to microaerophilic Fe(II)-oxidizer physiology; therefore, stalk morphology is a biosignature, as well as an indicator of local oxygen concentration at the time of formation. Observations of filamentous Fe(III)-oxyhydroxide microfossils from a ~170Ma marine Fe-Si hydrothermal deposit show that these morphological characteristics can be preserved in the microfossil record. This study demonstrates the potential of morphological biosignatures to reveal microbiology and environmental chemistry associated with geologic iron formation depositional processes.

Biogenic iron oxyhydroxide formation at mid-ocean ridge hydrothermal vents: Juan de Fuca Ridge

Here we examine Fe speciation within Fe-encrusted biofilms formed during 2-month seafloor incubations of sulfide mineral assemblages at the Main Endeavor Segment of the Juan de Fuca Ridge. The biofilms were distributed heterogeneously across the surface of the incubated sulfide and composed primarily of particles with a twisted stalk morphology resembling those produced by some aerobic Fe-oxidizing microorganisms. Our objectives were to determine the form of biofilm-associated Fe, and identify the sulfide minerals associated with microbial growth. We used micro-focused synchrotron-radiation X-ray fluorescence mapping (μXRF), X-ray absorption spectroscopy (μΕXAFS), and X-ray diffraction (μXRD) in conjunction with focused ion beam (FIB) sectioning, and high resolution transmission electron microscopy (HRTEM). The chemical and mineralogical composition of an Fe-encrusted biofilm was queried at different spatial scales, and the spatial relationship between primary sulfide and secondary oxyhydroxide minerals was resolved. The Fe-encrusted biofilms formed preferentially at pyrrhotite-rich (Fe 1− x S, 0 ⩽ x ⩽ 0.2) regions of the incubated chimney sulfide. At the nanometer spatial scale, particles within the biofilm exhibiting lattice fringing and diffraction patterns consistent with 2-line ferrihydrite were identified infrequently. At the micron spatial scale, Fe μEXAFS spectroscopy and μXRD measurements indicate that the dominant form of biofilm Fe is a short-range ordered Fe oxyhydroxide characterized by pervasive edge-sharing Fe–O 6 octahedral linkages. Double corner-sharing Fe–O 6 linkages, which are common to Fe oxyhydroxide mineral structures of 2-line ferrihydrite, 6-line ferrihydrite, and goethite, were not detected in the biogenic iron oxyhydroxide (BIO). The suspended development of the BIO mineral structure is consistent with Fe(III) hydrolysis and polymerization in the presence of high concentrations of Fe-complexing ligands. We hypothesize that microbiologically produced Fe-complexing ligands may play critical roles in both the delivery of Fe(II) to oxidases, and the limited Fe(III) oxyhydroxide crystallinity observed within the biofilm. Our research provides insight into the structure and formation of naturally occurring, microbiologically produced Fe oxyhydroxide minerals in the deep-sea. We describe the initiation of microbial seafloor weathering, and the morphological and mineralogical signals that result from that process. Our observations provide a starting point from which progressively older and more extensively weathered seafloor sulfide minerals may be examined, with the ultimate goal of improved interpretation of ancient microbial processes and associated biological signatures.

Environmental control versus phylogenic fingerprint in ontogeny: The example of the development of the stalk in the genus Guillecrinus (stalked crinoids, Echinodermata)

The stalk morphology of the deep‐sea stalked crinoid Guillecrinus changes a lot from juvenile to adult. As a result of its unusual morphology among the extant crinoids, its taxonomic and phylogenetic affinities remain unsettled. Distinctive morphological changes characterize the various growth stages in stalked crinoids. We conduct and discuss a detailed ontogenetic analysis of the stalk of the two species (Guillecrinus neocaledonicus and G. reunionensis) of this Indo‐Pacific genus, which was observed in its environment during submersible dives off New Caledonia. Analyses examined (1) morphological changes, (2) the degree of change in morphology, (3) architectural constraints, and (4) the functional constraints related to environmental factors. The relations between three levels of integration were examined: the ossicle (columnal), the stalk, and the complete individual. The changes in level of organization were estimated. The analysis reveals that the external stalk morphology of Guillecrinus goes from a pronounced xenomorphic type in juveniles, characterized by diversified columnal articulations, which provide the proximal and distal part of the stalk with a considerable degree of flexibility, to a dominant homeomorphic type in adults, characterized by columnal articulations which allow little or no movement. This ontogenetic change through a mosaic of heterochronic developments corresponds with a change in the hydrodynamic environment, from a turbulent to a laminar water flow, and from nutritional contraints. The extensive development of deep ligament fossae in adults and in the distal stalk of juveniles corresponds to a relatively low allocation of energy to the skeleton, rather than a functional necessity. Proximal columnals in juvenile Guillecrinus display characteristics of adult Hyocrinidae. Distal columnals exhibit the typical morphology observed in Bourgueticrinina. Juveniles stages of both proximal and distal columnals show a high degree of specialization (derived characters). Well‐supported classifications have typically placed the Bourgueticrinina and the Hyocrinidae in two very dissimilar groups. Specific characteristics from the three very different families Bathycrinidae, Guillecrinidae and Hyocrinidae appear to be expressed either separately (Hyocrinus or Bathycrinus) or together (Guillecrinus). Their expression appears to depend on functional and environmental constraints. The transformation of columnals from juvenile to adult shows the important role of hypermorphic processes. However, no evidence of phylogenetic recapitulation was observed. Does the evidence presented here support or disprove current taxonomic interrelationships? How does morphology relate to ontogeny? Is heterochrony involved?

SNOW ALGAE OF THE WINDMILL ISLANDS, CONTINENTAL ANTARCTICA: DESMOTETRA AUREOSPORA, SP. NOV. AND D. ANTARCTICA, COMB. NOV. (CHLOROPHYTA)

Two cryophilic Desmotetra species, D. aureospora, sp. nov., and D. antarctica (Fritsch) Ling appear to be unique to the southern hemisphere snow ecosystem, or at least to the Windmill Island region, Antarctica. They have not been encountered in previous extensive studies of the Arctic and northern alpine regions. Also unusual are the higher pH (6.8 and 7.8) and conductivities of 279 μS·cm−1 and 426 μS·cm−1 for habitat conditions of D. antarctica that can be attributed to the influence of penguin guano. Both species are characterized by cells enveloped in individual mucilage layers, 1–3 contractile vacuoles, and a cup‐shaped chloroplast containing a diffuse pyrenoid. The cells divided in three planes to form cubical loosely aggregated green cell packages embedded in mucilage. Vegetative cells of the two species cannot be distinguished with certainty; however, their zygospores are very different. Desmotetra aureospora has spherical, smooth‐walled, golden zygospores, whereas D. antarctica has pale, yellow green, aereolate zygospores. Mucilage stalk morphology of cells in stationary‐phase cultures can also be used to separate the two species. Zygospores of D. antarctica have previously been identified as the snow alga Trochiscia antarctica Fritsch. Both species are currently maintained in culture at the Australian Antarctic Division. The cultures did not grow at temperatures above 15° C. The two species are compared with the soil alga D. stigmatica (Deason) Deason et Floyd, the only other species in the genus, and also with Chlorosarcina stigmatica Deason strain T105. Results show that the three Desmotetra species form a natural group and that the absence or presence of a wall on the zoospore is of dubious value in classifications of green algal taxa above the species level.

Ethephon Alteration of Corn Plant Morphology

AbstractReduction in lodging, and plant and ear height resulting from ethephon application to corn (Zea mays L.) has been reported, but no attempt has been made to determine the influence of ethephon on internode properties and lodging. The objective of this study was to determine the influence of time and rate of ethephon application on plant and ear height, and length, diameter, and weight length−1 of internodes of corn plants. Ethephon was applied at rates of 0.0, 0.14,0.28, and 0.56 kg ha−1 at tassel elongation (TE), 6 d after tassel elongation (TE+6), and at ear elongation (EE) to Pioneer hybrid P3183 grown on Sharpsburg silty clay loam soil (fine, montmorillonitic, mesic Typic Argiudoll). Plant and ear height were reduced more by ethephon application at EE than at TE or TE+6. Increasing ethephon application from 0.0 to 0.56 kg ha−1 at EE resulted in plant and ear height reductions from 237 to 174 cm and 132 to 93 cm, respectively. Ethephon application resulted in reduced length of internodes, whereas diameter and weight length−1 increased. When applied at TE, ethephon resulted in a maximum of 48 mm reduction in internode length, 2.5 mm increase in internode diameter, and 0.017 g mm−1 increase in weight length−1; whereas application at EE resulted in a maximum of 99 mm reduction in internode length, 2.1 mm increase in internode diameter, and 0.019 g mm−1 increase in weight length−1. Stalk lodging was positively correlated to the length of Internodes 11 through 15. Application of ethephon resulted in large changes in the stalk morphology of corn plants, many of which contribute to reduced stalk lodging. Harvestable grain yield either declined or remained constant with ethephon application. These data suggest that ethephon may prove to be a useful research tool, especially for studying stalk lodging and plant architecture.

Relationship of stalk morphology and chemical composition to lodging resistance in maize (Zea mays L.) in a rainforest zone

SummaryField and laboratory studies were carried out in 1981 and 1982 to investigate the relationship of stalk morphology and chemical composition to lodging resistance in maize in the rainforest zone of Nigeria.Morphological characters correlated with lodging were plant height, diameter and length of basal internode, thickness of rind and weight of 5 cm basal section. Lodging was negatively correlated with grain yield, and with the percentages of total nonstructural carbohydrate, protein and potassium in the stalks. Premature stalk senescence and rot were common in varieties susceptible to lodging. Lodging had no relationship with leaf area and number of days from sowing to flowering.

ABNORMAL EGG STALK MORPHOLOGY IS CORRELATED WITH CLUTCH ATTRITION IN LABORATORY-MAINTAINED LOBSTERS (HOMARUS)

Female lobsters attach fertilized eggs to ovigerous setae on the pleopods by a stalk. Often a large percentage of the clutch is lost during the 6-12 month brooding interval, especially in laboratory-maintained females. The factors responsible for egg loss during brooding are undefined. We have compared the morphological characteristics of egg stalks from wild and laboratory-spawned females and correlated these characteristics with egg retention. Our data show that the morphology of egg stalks varies among laboratory-maintained lobsters and that there is a strong positive correlation between abnormal stalk morphology and clutch attrition. We conclude that improper formation of the egg stalk is a major cause of egg loss in laboratory-maintained lobsters.

Lower Stalk Development and Staging of Corn1

AbstractHail insurance adjustors determine corn (Zea mays L.) leaf stages after leaf number one has deteriorated and prior to tassel emergence by examining the longitudinal section of the lower stalk. They assume the sheath of leaf five is attached to the node immediately above the first elongated internode and determine leaf stage by” counting the leaves above leaf five. Since the leaf area destroyed vs. grain yield loss chart is based on plants with 18 leaves, adjustors modify the leaf stage on earlymaturing hybrids which develop fewer than 18 leaves.To test these techniques of plant staging, we conducted field experiments during 1973–75 to determine the effect of hybrid maturity, planting date, plant density, and geographical location on lower stalk morphology and leaf development of hybrids adapted to the northern corn belt. Experiments were conducted at Lamberton, Minn. on a Webster clay loam (Typic Haplaquoll), St. Paul, Minn. on a Waukegan silt loam (Typic Hapludoll), and Staples, Minn. on a Sverdrup sandy loam (Udic Haplaboroll). Leaf number five (counting the leaf with the rounded tip as number one) was spot sprayed with red paint. Subsequently the 10th leaf was similarly identified before leaf number five sloughed from the plant. At tasseling, plants were dug and stalks split to identify and record the leaf number attached to the node immediately above the first elongated internode. The number of leaves developed, number of leaves on the plant at tasseling, and length of the first four elongated internodes were recorded.In 2 of the 3 years, early planted corn had 0.5 to 0.8 more unelongated internodes compared with late planted corn. The number of unelongated internodes was negatively correlated (r = −0.99) with both heat units (base 10 C) and summation of maximum soil temperature (5 cm depth) for the 2nd week after planting. Hybrid maturity, density, and geographical location had no effect on the number of unelongated internodes.Number of developed leaves and number of leaves at tasseling increased as relative maturity increased in 2 of the 3 years. Averaged over entries, the lower 6.4 leaves sloughed as the stem enlarged and aerial adventitious roots developed. Number of developed leaves was greater for early planted compared with late planted corn but was not affected by test location or plant density.Lengths of the four lowest elongated internodes were greatest for early hybrids and decreased as maturity approached full season. The first elongated internode was longer on early planted than on late planted corn in 1974.Our data indicate early planted corn could be “understaged” by approximately one leaf by using the current procedure of splitting the lower stalk and assuming leaf five is attached to the node immediately above the first elongated internode. Understaging would result in underpayment of a hail loss claim. The early maturing hybrids develop fewer than 18 leaves. Therefore, the leaf stage should be modified (as is currently done) when adjusting loss claims on hybrids which develop fewer than 18 leaves. Without stage modification, loss claims would be underpaid.