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At least 19 recordsLinked to original sources
PubMed2025

GT1 regulates maize sex determination by affecting the jasmonate pathway.

Maize (Zea mays L.) is a monoecious plant with male and female flowers physically separated on different inflorescences-the tassel and the ear. Maize sex determination is controlled by a series of complicated developmental signals. Here, we characterized an EMS-induced maize feminized tassel mutant,tasselsilk1 (tsk1), and identified GRASSY TILLERS1 (GT1) as the causative gene. Phenotypic analysis of tsk1 mutants revealed that pistils fail to abort in both the tassel and ear, resulting in long sterile silks in the tassel and the development of an extra small kernel from the lower floret in the ear. RNA-seq and CUT&Tag analysis indicated that GT1 functioned as a repressor for flower organ development by regulating the JA biosynthesis and signaling pathways, specifically by directly promoting the expression of TASSELSEED1 (TS1), ZmMYC2A, ZmMYC2B. Together, we identified a new allele of GT1 and proposed that GT1 functions through JA biosynthesis and signaling pathways to regulate sex determination in maize.

Zea mays↗
PubMed2026

The MexMAGIC population reveals the genetic architecture of traits exhibiting clinal variation in Mexican native maize.

Defining the genetic basis of local adaptation is a key goal of evolutionary biology and crop improvement. Theory predicts that when selective pressures follow differences in the environment, a cline will be established. Clines can be exploited to uncover adaptive variation by association of alleles with the environment. However, monotonic phenotypic change over a cline is not necessarily mirrored in the behavior of genetic variants and population structure can further complicate analysis. To study genetic and phenotypic variation across the environment, we developed a multi-parent advanced generation inter-cross (MAGIC) population using eight Mexican native maize (Zea mays L. ssp. mays) varieties sourced from distinct agroecological zones. We evaluated the population in a common garden in Mexico and mapped tassel branching and flowering time, two traits that exhibit clinal variation. Variation in tassel branching was dominated by a single QTL with allele effects aligning to a negative elevational cline. By contrast, allele effects associated with 11 identified flowering time QTL were not consistently correlated with any one source environmental factor. Our observations support the prediction that genotype-environment association will be strongest under simple genetic architecture, although, even then, analysis in native populations may be confounded by population structure.

MAGIC↗
PubMed1976

Formation of packaging units in circket late spermatid nuclei as visualized by spreading techniques (1).

The nuclear organization of a particular step of cricket late spermiogenesis was examined by an electron microscope study of spermatids dispersed by air-liquid surface tension. Cell spreading techniques facilitate a display of condensing spermatid nuclei sufficient to allow interpretation of chromatin packaging processes. Results indicate that nuclei of late developing cricket spermatids are integrated by multiple packaging units as the result of an orderly aggregation of individual chromatin fibers. Each packaging unit consists of a thick fasicle, formed by the alignment of smooth chromatin fibers, which frays out into tassels of looped fibers.

Animals↗
PubMed1978

Scanning electron microscope study of the developing trout pelvic fin bud.

The growth of the pelvic fin bud has been studied with the SEM along with the characteristics of the pseudoapical epidermal ridge which occupies the free margin of the bud. SEM revealed fluffy protuberances in many of the epidermal cells, distinguishing the fin bud territory from adjacent areas. When the pseudoapical ridge appears, all the cells show this feature but their relative number decreases and these cells, termed the "tassel cells," are finally restricted to the base of the fin bud. This particular surface structure of the superficial cells may be unique to the fish, since it has not been heretofore reported in SEM studies of tetrapod limb bud.

Animals↗
PubMed1975

The first optic ganglion of the bee. I. Correlation between visual cell types and their terminals in the lamina and medulla.

Each visual unit (ommatidium) of the compound eye of the honey bee contains nine retinula cells, six of which end as axons in the first synaptic ganglion, the lamina, and three in the second optic ganglion, the medulla. A technique allowing light- and electron microscopy to be performed on the same silver-impregnated sections has made it possible to follow all types of retinula axons of one ommatidium to their terminals in order to study the shape of the terminal branches with their position in the cartridge. 1. The axons of retinula cells 1-6 (numbered according to Menzel and Snyder, 1974) end as three different types of short visual fibres (svf) in the lamina; the axons of retinula cells 7-9 run through the lamina to terminate in the medulla and are known as long visual fibres (lvf). Retinula cells of each type are identified by the location of their cell bodies and by the direction of their microvilli. The retinula cells 1 and 4 (group I according to Gribakin, 1967) end as svf type 1 with three tassel-like branches in stratum B of the first synaptic region. The pair of cells 3, 6 and the pair 2, 5 (group II) end in the first synaptic region in stratum A. Cells 3 and 6 have forked endings, svf type 2, whereas cells 2 and 5 have tapered endings, svf type 3. The remaining retinula cells 7, 8 and 9 have long fibres. Nos. 7 and 8 (group III) have tapered endings and are termed lvf types 1 and 2, respectively. The 9th cell is the lvf type 3 with a highly branched ending. 2. The nine axons in the bundle from one ommatidium have relative positions which do not change from the proximal retina to the monopolar cell body layer. 3. By following silver-stained retinula cells and their corresponding axons, it is possible to describe mirror-image arrangements of fibres in the axon bundles in different parts of the eye. This correlation of numbered retinula cells with specific axon types, together with the highly organized pattern in an axon bundle, allows the correlation between histological and physiological findings on polarization and colour perception.

Animals↗
PubMedDate not supplied

Do mosquitoes breed in maiza plant axils?

One thousand five hundred and seven tasselled maize plants in Lusaka and 96 in a rural village where mosquitoes were plentiful, have been surveyed. About 28% of plants contained water mainly around developing cobs. No mosquito larvae were found. It is concluded that maize slashing as part of the programme for malaria control is unjustified.

Breeding↗
PubMed1992

Anatomy, histology, and pathology of coronary arteries: a review relevant to new interventional and imaging techniques--Part II.

In the last 15 years, intense interest has focused on various interventional, pharmacologic, and mechanical forms of therapy for the treatment of atherosclerotic coronary artery disease. Many techniques and devices (dilating balloons, perfusion catheters, thermal probes and balloons, lasers, atherectomy devices, stents, intravascular ultrasound) have been used or are under study for future use. Many of these techniques and devices require an understanding of histologic and pathologic features of the coronary arteries and diseases which affect them. This article reviews selective areas of anatomy, histology, and pathology relevant to the use of various new interventional techniques. Part II of this four-part review will focus on aging changes seen in the epicardial coronary arteries and will review selected features of atherosclerotic plaque, including fissure and topography.

Angioplasty, Balloon, Coronary↗
PubMed1992

Anatomy, histology, and pathology of coronary arteries: a review relevant to new interventional and imaging techniques--Part III.

In the last 15 years, intense interest has focused on various interventional, pharmacologic, and mechanical forms of therapy for the treatment of atherosclerotic coronary artery disease. Many techniques and devices (dilating balloons, perfusion catheters, thermal probes and balloons, lasers, atherectomy devices, stents, intravascular ultrasound) have been used or are under study for future use. Many of these techniques and devices require an understanding of histologic and pathologic features of the coronary arteries and diseases which affect them. This article reviews selective areas of anatomy, histology, and pathology relevant to the use of various new interventional techniques. Part III of this four-part review focuses on eccentric and concentric plaques, formation of coronary thrombus, and status of the "infarct artery" after mechanical and pharmacologic forms of acute reperfusion therapy.

Angioplasty, Balloon, Coronary↗
PubMed1992

Anatomy, histology, and pathology of coronary arteries: a review relevant to new interventional and imaging techniques--Part IV.

In the last 15 years, intense interest has focused on various interventional pharmacologic and mechanical forms of therapy for the treatment of atherosclerosis coronary artery disease. Many techniques and devices (dilating balloons, perfusion catheters, thermal probes and balloons, lasers, atherectomy devices, stents, intravascular ultrasound) have been used or are under study for future use. Many of these techniques and devices require an understanding of histologic and pathologic features of the coronary arteries and diseases which affect them. This article reviews selective areas of anatomy, histology, and pathology relevant to the use of various new interventional techniques. Part IV of this review will focus on congenital coronary artery anomalies, myocardial bridges, coronary aneurysm, emboli, and dissection and clinical implications regarding echocardiographic imaging techniques.

Coronary Aneurysm↗
PubMed2026

Expression dynamics of mCry3A and eCry3.1Ab transgenes in Bt corn hybrids across growth and environments.

In 2017 and 2018, studies were conducted in Iowa, US across three environments with a history of greater than expected corn rootworm injury i.e., greater than one node of injury to (US EPA 2009) and one environment without rootworm injury, and at different growth stages, to determine the expression levels of mCry3A and eCry3.1Ab transgenes in the roots of different Bt corn hybrids namely the molecular stack (MZIR098), breeding stack (MIR604 × 5307), 5307 and MIR604. ELISA results showed that expressions of both mCry3A and eCry3.1Ab transgenes, were higher in the MZIR098 molecular stack and breeding stack (MIR604 × 5307), than the MIR604 and 5307 at V3 and VT growth stages over both years. To protect the roots from feeding damage by the corn rootworm larvae, expression of the transgenes must be high at the V3 growth stage. The expression of the transgene was significantly impacted by the stage of plant growth while the environments with greater than expected corn rootworm injury did not impact expression of the transgenes. It was found that the expression of mCry3A and eCry3.1Ab transgenes were high at the V3 plant growth stage compared to the VT growth stage. Stacking two or more genes together in the same plant such as the molecular and breeding stacks have the potential to protect roots in environments with higher-than-expected damage and slow down the evolution of resistance in field populations of rootworms.

Zea mays↗
PubMed1979

Mutagens in the feces of 3 South-African populations at different levels of risk for colon cancer.

The incidence of mutagens in the feces of 3 South-African populations at different risk levels for colon cancer has been determined. Lyophilized fecal samples were extracted with ether and the mutagenicity of the extracts determined using the Salmonella/mammalian microsome mutagenicity test. 19% of the samples from urban white South-Africans, a population at a high risk for colon cancer, were mutagenic using Salmonella typhimurium strain TA100. This incidence was significantly greater (p less than 0.001) than the incidence of mutagen excretion in the low-risk populations of urban blacks (2%) and rural blacks (0%). This pattern was also obtained using Salmonella typhimurium strain TA98. The incidence of mutagen excretion for urban whites was 10%, as compared to 5% and 2% for urban and rural blacks, respectively.

Black People↗
PubMed1978

Gonadotrophin levels and ovarian development in the neonatal ewe lamb.

Ovarian weight has been shown to increase markedly in the newborn ewe lamb, and factors which might contribute to this growth were examined. Follicle development was studied in the ovaries of 28 lambs aged 0, 2, 4, 6, 8 and 10 weeks. Plasma samples, pituitaries and one ovary were assayed for gonadotrophin or steroid hormone content. No significant differences between age groups were found in pituitary LH concentration or mean plasma LH. Pituitary FSH concentration increased with age, except for a small decrease at 8 weeks, but no significant changes were seen in plasma FSH. Ovarian progesterone and oestradiol concentrations did not appear to be associated with follicular development. Growing follicles were most numerous at 2 weeks whilst total vesicular follicles reached a peak at 4 weeks. Most vesicular follicles were less than 1.4 mm in diameter. Advanced atresia in vesicular follicles became apparent by 4 weeks although early signs were present in younger lambs. Fluctuations in gonadotrophin levels do not appear to be responsible for variations in number and size of vesicular and growing follicles in the lamb ovary. Other possible explanations are discussed.

Animals↗
PubMed2026

Epigenetic age acceleration is not strongly associated with cardiorespiratory fitness in heart failure: a pilot study.

BACKGROUND: In heart failure (HF), standard measures such as left ventricular ejection fraction and cardiopulmonary exercise testing incompletely capture interindividual differences in disease status or prognosis. DNA methylation (DNAm) epigenetic clocks, which estimate biological age and epigenetic age acceleration (EAA), may provide complementary insight into cardiorespiratory fitness and systemic aging in HF. RESEARCH DESIGN AND METHODS: We analyzed peripheral blood DNAm from fourteen patients enrolled in REDHART2, a clinical trial of interleukin-1 blockade following hospitalization for acute systolic HF. Genome-wide DNAm was assayed using Illumina EPIC arrays and several clocks were applied to these data. Associations between biological age or EAA and cardiorespiratory fitness measures, inflammatory markers, and clinical parameters were evaluated. RESULTS: All epigenetic clocks demonstrated moderate to strong correlations with chronological age. Biological age was consistently associated with measures of cardiorespiratory fitness, particularly oxygen consumption normalized to fat free mass (VO2_FFM). However, chronological age showed similar associations, and biological age did not significantly improve prediction of VO2 parameters beyond chronological age alone. EAA was not significantly associated with cardiorespiratory fitness for any clock. CONCLUSIONS: In this pilot study, neither biological age nor EAA provided significant predictive value beyond chronological age for cardiorespiratory fitness in patients with HF. CLINICAL TRIAL REGISTRATION NUMBER: NCT03797001.

DNA methylation↗
PubMedDate not supplied

Bacteriophages of Bacteroides.

Sixty-eight bacteriophages specific for nine species (DNA homology groups) of Bacteroides were isolated from sewage. Four distinct morphological types were isolated, three of which had not previously been described. Attempts to use these phages to transduce Bacteroides fragilis were unsuccessful. A total of 91 phage-susceptible strains of Bacteroides were used with these phages in a study of the feasibility of developing a scheme for identification of Bacteroides species. Blind trials were performed with 10 B. fragilis-specific phages and a collection of over 200 bacterial strains, including 144 strains of B. fragilis. Of the strains of B. fragilis, 78% were identified correctly within 24 hr. A phage-carrier state, or pseudolysogeny, was observed with most of the phage-host systems, and this state was studied in detail with B. fragilis phage Bf-1. The presence of a thick capsule around some cells in a pure culture of a host strain appears to render these cells resistant to phage infection, thus perpetuating the carrier state. It is suggested that such capsules may play a role in the virulence of strains of Bacteroides.

Bacteriophages↗