Cell Cutoff Research Articles

Evidence for lower CD4<sup><b>+</sup></b> T cell and higher viral load in asymptomatic HIV-1 infected individuals of India: Implications for therapy initiation

We have earlier documented that the south Indian population had lower CD4 counts. The aim of this study was to investigate a previous suggestion on a new CD4+ T cell cut off and association with HIV-1 RNA levels for decision on anti retroviral therapy in India (south). We evaluated a new methodology i.e., artus real-time PCR and CD4+ T cell count by Guava EasyCD4 system. From 146 HIV infected individuals seen at a tertiary care centre, blood was collected for CD4+ T cell and HIV-1 RNA estimation. The receiver operating characteristic curve cut off value for the CD4 counts to distinguish between CDC clinical categories A and B was 243 cells/microL, and to distinguish B and C was 153 cells/microL. The RNA level that differentiated CDC A and B was 327473 RNA copies/mL, while for CDC B and C was 688543 copies/mL. There was a significant negative correlation (r = -0.55, P + T cell counts in HIV infected individuals. A majority with CD4 counts of 201-350 cells/microL in our population had higher viral load than the treatment threshold suggested by the International AIDS society and the above two methodologies are useful in monitoring HIV infections.

How sensitive is the synovial fluid white blood cell count in diagnosing septic arthritis?

Objective This study was conducted to determine the sensitivity of the current standard for synovial fluid leukocytosis analysis in diagnosing infectious arthritis or a septic joint. How accurate is the standard synovial fluid white blood cell (WBC) cutoff of 50 000 WBC/mm 3 to rule out septic arthritis? Methods We conducted a retrospective study at an urban tertiary care medical center with 50 000 adult emergency department visits per year. The study population consisted of patients with infectious arthritis confirmed by synovial fluid culture growth of a pathogenic organism. The study period lasted from January 1996 to December 2002. Extracted data included synovial fluid leukocyte count, Gram's stain, culture, past medical history, and discharge diagnosis. Fisher exact test was used to compare proportions. Sensitivity and means were calculated with 95% confidence intervals (CI). Results There were 49 culture-positive synovial fluid aspirates in the 6-year study period. Nineteen (39%) of 49 patients (95% CI, 25%-52%) had a synovial WBC of less than 50 000/mm 3 and 30 (61%) of 49 patients (95% CI, 48%-75%) had a synovial WBC of more than 50 000/mm 3. The sensitivity of the 50 000 synovial WBC/mm 3 cutoff was 61% (95% CI, 48%-75%). Twenty-seven (55%) of 49 patients had a negative Gram's stain (95% CI, 41%-69%) and 15 (56%) of 27 patients (95% CI, 37%-74%) with negative Gram's stain had a synovial WBC of less than 50 000/mm 3. Conclusion A synovial fluid WBC cutoff of 50 000/mm 3 lacks the sensitivity required to be clinically useful in ruling out infectious arthritis.

Low-temperature study of lithium-ion cells using a Li ySn micro-reference electrode

Lithium-ion batteries are considered to be the next battery system for hybrid electric vehicles (HEVs) due to their high power density. However, their power is severely limited at −30 °C and the concern exists that lithium metal could plate on the negative electrode during regen (charge) pulses. The goal of this work is to determine the reason for this poor low-temperature performance using an in situ Li ySn micro reference electrode (RE) over a wide temperature range of 30 °C to −30 °C. A variety of negative and positive electrode materials with unique morphologies was used in this work to help elucidate the dominant low-temperature mechanism. In this work, it was observed that the potential of graphite negative electrodes does dip below lithium potentials not only during charge pulses, but also under normal charging if the cell cutoff voltage is not reduced from its room-temperature setting of 4.1 V, whereas hard carbon electrodes do not because they operate further from lithium potential. The most surprising finding from this work was that a second impedance mechanism dominates below 0 °C that affects the positive and negative electrodes almost equally. This suggests that the responsible phenomenon is independent of the active material and is most likely a pure electrolyte-interface effect.

Conspecificity of Holmesia neurymenioides with Reinboldiella warburgii (Ceramiales, Rhodophyta) from northeastern Taiwan on the basis of cystocarp development and rbcL sequence analysis

S.-M. Lin and M.H. Hommersand. 2007. Conspecificity of Holmesia neurymenioides with Reinboldiella warburgii (Ceramiales, Rhodophyta) from northeastern Taiwan on the basis of cystocarp development and rbcL sequence analysis. Phycologia 46: 247–256. DOI: 10.2216/06-48.1Holmesia neurymenioides (Okamura) Okamura was originally described from St. Tiago, northeastern Taiwan; however, this alga has not been re-collected in Taiwan since it was first described and its carposporophyte development is virtually unknown. Its growth pattern is not typical for Delesseriaceae, in which the axial cell cuts off two lateral and two transverse periaxial cells. Instead, the vegetative development corresponds to a basal type in the tribe Ceramieae (Ceramiaceae) in which the axial cell cut off two lateral and four transverse periaxial cells. The procarp consists of a three- to four-celled carpogonial branch and a single lateral sterile filament borne on either of the two lateral periaxial cells, and the carposporangia-bearing gonimoblasts are more or less naked, surrounded only by five involucral branchlets that originate from the other five periaxial cells in the fertile axial segment. We conclude that this alga does not belong in the family Delesseriaceae but that it should be placed in the genus Reinboldiella in the family Ceramiaceae. Its correct name is Reinboldiella warburgii (Heydrich) Yoshida & Mikami on the basis of cystocarp development. This taxonomic revision is highly supported by rbcL sequence analysis.

Two creeping Ceramium species (Ceramiaceae, Rhodophyta) from the Florida Keys: C. reptans sp. nov. and recircumscription of C. codii (Richards) Mazoyer

Tae Oh Cho and Suzanne Fredericq. 2006. Two creeping Ceramium species (Ceramiaceae, Rhodophyta) from the Florida Keys: C. reptans sp. nov. and recircumscription of C. codii (Richards) Mazoyer. Phycologia 45: 495–504. DOI: 10.2216/05-44.1On the basis of comparative morphology, a new creeping Ceramium species with incomplete and narrow nodal cortication, C. reptans sp. nov. is described from the Florida Keys, USA, where it co-occurs epiphytically with C. codii on the same host, Hypnea spinella. Ceramium reptans sp. nov. is recognized by a prostrate axis producing unbranched upright axes dorsally; five periaxial cells per axial cell; three cortical cells cut off per periaxial cell, with the first acropetal cortical cell becoming the pseudoperiaxial cell that extends longitudinally parallel to the level of neighboring periaxial cells, a second acropetal and third basipetal horizontal cortical cell; and cruciately divided tetrasporangia in whorls bulging from a single node appressed to the contiguous node below on upright axes, 3–6 segments below the apex. Ceramium codii, described from Bermuda, is recognized by a prostrate axis producing unbranched, upright axes dorsally, four periaxial cells per axial cell, three cortical cells cut off per periaxial cell with the basipetal cortical cell cut off horizontally on the prostrate axis, and 1–2 tetrahedrally divided tetrasporangia produced per periaxial cell. Among the described creeping Ceramium species; C. codii, C. bisporum, C. cingulatum, C. cingulum, C. dorsiventrale, C. incospicuum, C. jolyi, C. luetzelburgii, C. procumbens, C. poeppigianum, C. punctiforme, C. serpens, and C. tenerrimum var. brevizonatum f. repens, none has the characteristic pseudoperiaxial cells of C. reptans. Ceramium codii may not be a widespread species as is widely reported in the literature.

MOLECULAR SYSTEMATICS OF CERAMIUM AND CENTROCERAS (CERAMIACEAE, RHODOPHYTA) FROM BRAZIL1

Morphological investigations identified 11 Ceramium Roth species, of the 18 previously reported from Brazil. Phylogenetic analyses of sequences of the chloroplast‐encoded rbcL gene confirmed the presence of seven of these species. Three other species are reported from Brazil for the first time. Ceramium affine Setchell & Gardner and C. filicula Harvey ex Womersley were previously known only from the Pacific Ocean (Mexico and Australia, respectively). A new species, C. fujianum Barros‐Barreto et Maggs sp. nov., is described here. Its general habit is similar to that of C. strictum sensu Harvey from Europe but it has one less periaxial cell than C. strictum; its cortical filament arrangement is closest to C. deslongchampsii Chauvin ex Duby, also from Europe, but whorled tetrasporangia partially covered by cortical cells differ strikingly from the naked protruding tetrasporangia of C. deslongchampsii. Ceramium species in which each periaxial cell cuts off transversely only a single basipetal cell formed a robust clade. The genus Ceramium as represented in Brazil is not monophyletic with respect to Centroceras Kützing and Corallophila Weber‐van Bosse; Ceramium nitens, which has axial cells completely covered by rounded cortical cells formed by acropetal and basipetal filaments, did not group with any Ceramium clade but was weakly allied to a species of Corallophila. All three Brazilian Centroceras sequences were attributed to a single species, C. clavulatum.

Significance of extreme leukocytosis in the evaluation of febrile children

Background: Emergency department evaluation of young febrile children often includes a white blood cell count. Although a high white blood cell count is associated with an increased likelihood of infection, the clinical significance of extreme leukocytosis (EL), defined as a white blood cell count of 25,000/mm 3 , has not been well-studied. Objective: To determine diagnoses associated with EL in febrile children evaluated in a pediatric emergency department and to compare rates of serious bacterial infection in those with EL and in those with more modest leukocytosis (LK) (15,000‐24,999/mm 3 ). Methods: A retrospective case-control study of children 2‐24 months of age was performed. Those with EL were frequency ageand gender-matched to controls with LK. Results: Sixty-nine patients with EL and 94 patients with LK were included. The mean age was 9.9 months, and 91 (56%) patients were male. The diagnoses were similar between the 2 groups, with otitis media, viral syndrome and pneumonia being the most common. The rates of proven serious bacterial infection were similar between EL (25%; 95% confidence interval, 15‐36%) and LK (17%; 95% confidence interval, 10‐26%) patients. Using different white blood cell cutoff points did not distinguish between patients with and without serious bacterial infection. Conclusion: Young febrile children whose emergency department evaluation revealed EL had diagnoses and rates of serious bacterial infection similar to those of children with LK.

Significance of Extreme Leukocytosis in the Evaluation of Febrile Children

Emergency department evaluation of young febrile children often includes a white blood cell count. Although a high white blood cell count is associated with an increased likelihood of infection, the clinical significance of extreme leukocytosis (EL), defined as a white blood cell count of > or = 25,000/mm, has not been well-studied. To determine diagnoses associated with EL in febrile children evaluated in a pediatric emergency department and to compare rates of serious bacterial infection in those with EL and in those with more modest leukocytosis (LK) (15,000-24,999/mm). A retrospective case-control study of children 2-24 months of age was performed. Those with EL were frequency age- and gender-matched to controls with LK. Sixty-nine patients with EL and 94 patients with LK were included. The mean age was 9.9 months, and 91 (56%) patients were male. The diagnoses were similar between the 2 groups, with otitis media, viral syndrome and pneumonia being the most common. The rates of proven serious bacterial infection were similar between EL (25%; 95% confidence interval, 15-36%) and LK (17%; 95% confidence interval, 10-26%) patients. Using different white blood cell cutoff points did not distinguish between patients with and without serious bacterial infection. Young febrile children whose emergency department evaluation revealed EL had diagnoses and rates of serious bacterial infection similar to those of children with LK.

P27(Kip1) expression and grading of breast cancer diagnosed on cytological samples.

The progressive reduction in p27(Kip1) (p27) protein immunohistochemical staining with increasing histological grading is a well-established finding occurring in breast cancer, and its role as diagnostic complement and prognostic marker has been thoroughly evaluated. To clarify whether this test may be applied to breast cytopathology, we performed p27 immunostaining on fresh fine-needle cytology (FNC) samples from 10 benign and 40 malignant breast lesions. On average, p27 immunostaining was significantly lower in carcinomas than in benign lesions (P < 0.005). In particular, among carcinomas, p27 immunostaining progressively reduced from well-to poorly differentiated lesions (G1 vs. G2, P < 0.05; G1 vs. G3, P < 0.001; G2 vs. G3; P < 0.001). A similar trend was noted in a subgroup of 20 matched FNCs and histological samples of breast carcinomas, when p27 immunostaining on FNCs was stratified according to the histological grading (G1 vs. G2, P = 0.18; G1 vs. G3, P < 0.05; G2 vs. G3, P < 0.05). In addition, p27 immunostaining on FNCs showed a good positive correlation with that on histology (Spearman R = 0.58; P < 0.01), with a diagnostic concordance between samples of 85%, by using the standard 50% positive cell cutoff. Taken in concert, our data suggest that p27 immunostaining is a reliable marker of tumor cell differentiation in breast cytopathology as well as in histopathology. Accordingly, staining FNCs for p27 may be an useful complement in addition to cytological grading in the preoperative assessment of breast cancer.

Observations on reproductive morphology and new records of Rhodomelaceae (Rhodophyta) from the Canary Islands, including Veleroa complanata sp. nov.

Polysiphonia funebris and P. tenerrima are examined mainly in relation to their vegetative and reproductive features. In P. funebris the procarps and cystocarps are described for the first time, and it is confirmed that the species exhibits all the vegetative and reproductive features presently used in the delineation of the genus Polysiphonia. The mainly Mediterranean P. tenerrima is reported for the first time in the Atlantic Ocean. This epi-endophyte on Nemalion helminthoides has ecorticate axes with four pericentral cells, abundant trichoblasts spirally ananged, rhizoids cut off from pericentral cells, tetrasporangia produced in spiral series and apparently three-celled carpogonial branches, all diagnostic characters of the genus Neosiphonia. Tetrasporangial plants in the western Atlantic species Dipterosiphonia reversa are described for the first time from a collection that represents the first record of this species in the eastern Atlantic Ocean. Tetrasporangia are produced (one per segment) in short linear series in pinnate laterals, with fertile segments consisting of five pericentral cells; the fertile pericentral cell cuts off two sporangial cover cells. Veleroa complanata Afonso-Carrillo & Rojas-González sp. nov., known only from Tenerife in the Canary Islands, is unique among species of the genus Veleroa because of its progressively corticated polysiphonous axes and its two different types of spirally arranged, determinate, pigmented, persistent trichoblasts. These are unbranched in prostrate and fertile portions of erect axes, but branched, with up to eight alternate-distichous complanate laterals, in vegetative erect axes. A comparative table of the morphological attributes of the species currently accepted in Veleroa is given.

Management of Febrile Children in the Age of the Conjugate Pneumococcal Vaccine: A Cost-Effectiveness Analysis

The optimal practice management of highly febrile 3- to 36-month-old children without a focal source has been controversial. The recent release of a conjugate pneumococcal vaccine may reduce the rate of occult bacteremia and alter the utility of empiric testing and treatment. The objective of this study was to determine the cost-effectiveness of 6 different management strategies of febrile 3- to 36-month-old children at current and declining rates of occult pneumococcal bacteremia. A cost-effectiveness (CE) analysis was performed to compare the strategies of "no work-up," "clinical judgment," "blood culture," "blood culture + treatment," "complete blood count (CBC) + selective blood culture and treatment," and "CBC and blood culture + selective treatment." A hypothetical cohort of 100 000 children who were 3 to 36 months of age and had a fever of >/=39 degrees C and no source of infection was modeled for each strategy. Our main outcome measures were cases of meningitis prevented, life-years saved compared with "no work-up," total cost (1999 dollars), and incremental CE ratios. When compared with "no work-up," the strategy of "CBC + selective blood culture and treatment" using a white blood cell (WBC) cutoff of 15 x 10(9)/L prevents 48 cases of meningitis, saves 86 life-years per 100 000 patients, and is less costly at the current rate of bacteremia (1.5%). Using the strategy of "CBC + selective blood culture and treatment" with a lower WBC cutoff of 10 x 10(9)/L costs an additional $72 300 per life-year saved. If the rate of bacteremia declines to 0.5%, then the incremental CE ratio of "clinical judgment" compared with "no work-up" is $38 000 per life-year saved; however, strategies that include empiric testing or treatment result in CE ratios greater than $300 000 per life-year saved. "CBC + selective blood culture and treatment" using a WBC cutoff of 15 x 10(9)/L is cost-effective at the current rate of pneumococcal bacteremia. If the rate of occult bacteremia falls below 0.5% with widespread use of the conjugate pneumococcal vaccine, then strategies that use empiric testing and treatment should be eliminated.

VALIDATION AND REFINEMENT OF THE ACTG STAGING SYSTEM FOR AIDS-ASSOCIATED KAPOSI'S SARCOMA (KS)

Background: A KS staging classification that correlates features of the disease with prognosis would facilitate the identification of optimal therapeutic strategies. Recognition of the intimate link between KS and HIV-1 infection led, in 1988, to proposal by the ACTG Oncology Committee of a KS staging system that classified patients (pts) according to tumor extent (T), immune system status (I), and evidence for HIV-1-associated systemic illness (S). Methods: HIV seropositive pts with biopsy-proven KS were staged as either good- or poor-risk using TIS criteria prior to entering ACTG KS treatment trials and were followed for survival. Associations between survival and the TIS variables were evaluated by both univariate (logrank test) and multivariate (Cox proportional hazard regression) analyses. Results: 294 pts enrolled in 8 trials from 4/89 to 1/95. Median f/u was 11 months, and 47.3% of pts were dead at the time of analysis. The numbers of pts with good and poor risk features for each of the TIS variables were 104 and 185 for T, 84 and 210 for I (using 200 CD4 cells/ µL as a cutoff), and 53 and 240 for S. Logrank tests showed a significantly shorter estimated median survival for pts in the poor risk category for each of the TIS variables. Cox proportional hazards regression yielded a final model that included I, T and an interaction variable (IxT). Examination of crude death rates in different CD4 strata suggested that a CD4 count of 150/ µL was a better cutpoint for predicting survival than 200/ µL, and the model selected using the 150 cell cutoff included only I and T, without a significant interaction variable. Among pts with poor risk T stage, significant survival differences were not detected for pts with and without pulmonary KS. Conclusions: The ACTG TIS staging system for AIDS-associated KS is a valid predictor of survival, but a modified system, using 150 CD4 cells/µL to distinguish good- and poor-risk I stage, yields a simplified and more predictive model. Tumor stage added to CD4 counts in predicting survival in pts whose immune function was least impaired. Additional staging refinements may be possible by including other variables such as viral load, markers of immune activation, or more specific poor-risk tumor features.

(1063) Proposal to conserve Falklandiella Kylin (Rhodophyceae: Ceramiaceae)

Falklandiella was proposed by Kylin (1956) as a genus of Ceramiaceae, distinguished from other distichously branched members of the Ptiloteae in that the determinate branches remain uncorticated. Ptilota harveyi Hook. f. (in Hooker & Harvey, 1845: 271) was designated as type, while P. pellucida Harv. (in Hooker, 1854-1855: 257) was included as a second species. Papenfuss (1958: 105), noting that P. pellucida was the type of an older generic name, Dasyptilon G. Feldmann (1950: 308), adopted that name in place of Falklandiella. As emphasized by Moe & Silva (1979: 397), however, P. pellucida and P. harveyi are not congeneric. In P. pellucida the procarp is produced directly by the basal cell of a determinate branch, while in P. harveyi it is produced by a pericentral cell cut off from an axial cell near the apex of a determinate branch. In P. pellucida the supporting cell lies in the plane of thallus branching and the carpogonial branch bends upward around that cell, while in P. harveyi the supporting cell is perpendicular to the plane of thallus branching and the carpogonial branch bends horizontally around the axis bearing the supporting cell. Moreover, the tetrasporangia in P. pellucida are cruciately divided and are adaxial and sessile on branchlets of a determinate branch, while in P. harveyi they are tetrahedrally divided and terminal on the axis and on numerous branchlets of a determinate branch. Kylin's inclusion of the type of Dasyptilon in his initial circumscription of Falklandiella renders the latter name superfluous and illegitimate in accordance with Art. 63.1 of the Code (Greuter & al., 1988). Falklandiella was proposed for conservation by Silva (1980: 131), but this proposal (494) was rejected by the Committee for Algae (Christensen, 1987: 68) under the mistaken assumption that changes in Art. 7 and 63 made during the Thirteenth International Botanical Congress at Sydney in August 1981 allowed for the correct use of the name provided that the offending type was excluded. The alleged change involved Art. 63.3, which specifies which nomenclaturally superfluous names are not illegitimate. To the preexisting category of names based on legitimate basionyms was added a second category, suprageneric names based on the stem of a legitimate generic name. However, provision for the purification of nomenclaturally superfluous generic names is not to be found in

Pollen development in orchids 4. Cytoskeleton and ultrastructure of the unequal pollen mitosis inPhalaenopsis

The unequal first mitosis in pollen ofPhalaenopsis results in a small generative cell cut off at the distal surface of the microspore and a large vegetative cell. No preprophase band of microtubules is present, but polarization of the microspore prior to this critical division is well marked. A generative pole microtubule system (GPMS) marks the path of nuclear migration to the distal surface, and the organelles become unequally distributed. Mitochondria, plastids and dictyosomes are concentrated around the vegetative pole in the center of the microspore and are almost totally excluded from the generative pole. The prophase spindle is multipolar with a dominant convergence center at the GPMS site. The metaphase spindle is disc-shaped with numerous “minipoles” terminating in broad polar regions. In anaphase, the spindle becomes cone-shaped as the spindle elongates and the vegetative pole narrows. These changes in spindle architecture are reflected in the initial shaping of the telophase chromosome groups. F-actin is coaligned with microtubules in the spindle and is also seen as a network in the cytoplasm. An outstanding feature of orchid pollen mitosis is the abundance of endoplasmic reticulum (ER) associated with the spindle. ER extends along the kinetochore fibers, and the numerous foci of spindle fibers at the broad poles terminate in a complex of ER.

A Method for Calculating Electric And Magnetic Fields in TEM Cells at ELF

A method is presented whereby the electric and magnetic field distributions within rectangular-strip transmission lines (TEM cells) can be calculated. Quasi-static approximations are employed, thereby restricting the validity of the results to operational frequencies well below the cell cutoff frequency. The method is illustrated by calculating the fields within an existing structure used in biological experimentation. Where possible, calculations are compared with measured data.

Velocity selectivity in the cat visual system. III. Contribution of temporal factors.

In 149 units from area 17 and 48 units from area 18 the responses to stationary stimulation of different durations were compared with the responses to the same stimulus (a 0.3 degrees-wide light or dark bar) moving at different velocities. The aim was to test the hypothesis that the range of effective velocities depends on the time needed for the bar to cross the receptive field. Forty-two percent of the area 17 cells and 8% of the area 18 cells responded poorly or not at all to briefly presented stationary stimulation. These cells were unable to respond at high velocities, and for these "duration-sensitive" cells the velocity characteristics are well predicted on the basis of responses to stationary stimulation of different durations. Cells that responded equally well to periods of stationary stimulation ranging from 12.5 to 3,200 ms ("duration-insensitive cells") were found to be able to respond at all equivalent velocities, but their preference for either high, low, or intermediate velocities was not reflected in differences in responsiveness to the different durations tested. Duration-sensitive cells in area 17 tended to have a receptive field near the area centralis, and 73% of them were classified as S-family cells, one third being end-stopped S-cells. In contrast only 18% of the duration-insensitive cells were of the S family, and these S-family cells were rarely end-stopped (1/12) or rarely had receptive fields within 5 degrees of the fovea (3/12). Duration-sensitive cells had very long latencies (median 285 ms) in response to a stationary flashed light bar of 1 s duration but much shorter latencies (median 91 ms) when tested with a slowly moving light bar. This difference was not seen in duration-insensitive cells (median latencies = 61 and 59 ms). The ability to respond at high velocity was contrast dependent. At a low contrast level all cells failed to respond to brief stimulation, whether moving or stationary. At high contrast levels only the duration-insensitive cells showed an increased responsivity to brief stimuli. The absence of responses in duration-sensitive cells to brief stimuli of high contrast may depend upon suppressive influences reaching these cells before the excitatory influences. We conclude that the velocity upper cutoff of most S-family cells with a central receptive field can be predicted from a knowledge of the minimum duration of stationary presentation required for their activation (median ON duration threshold, 200 ms).(ABSTRACT TRUNCATED AT 400 WORDS)

Morphological studies of members of the tribe Agardhielleae (Solieriaceae, Rhodophyta)

Abstract Sarcodiotheca furcata and S. dichotoma grow multiaxially with a single periaxial cell cut off from each succeeding axial cell in an orthostichous file. Branching of primary apices is dichotomous, apparently resulting from division of the apical cells into two equal initials, whereas lateral branches are formed adventitiously from surface cortical cells. The auxiliary cell complex, consisting of the auxiliary cell and surrounding darkly-staining inner cortical cells, is recognizable prior to diploidization. Typically, two unbranched and non-septate connecting filaments are formed from each fertilized carpogonium. Fusion of a connecting filament with an auxiliary cell stimulates development of the involucre. A gonimoblast initial is cut off from the auxiliary cell and divides forming a compact cluster of gonimoblast cells. In the first phase of carposporophyte development the gonimoblast radiates out and fusions occur between gonimoblast and vegetative cells producing a central placenta. In the sec...

Cell repair through cell fusion in the red alga Griffithsia pacifica.

When an intercalary shoot cell of the red algaGriffithsia pacifica is killed, the cell may be replaced through the wound-healing process of cell repair. During cell repair the cells on either side of the dead cell cut off new cells towards the dead cell. The superjacent cell produces a rhizoid; the subjacent cell produces an atypical shoot cell. The two new cells grow towards each other through the lumen of the dead cell. When they meet, they fuse; the resulting cell expands laterally to fill the cavity of the dead cell and is transformed into a typical intercalary shoot cell, morphologically and physiologically indistinguishable from the killed cell it replaces. The entire cell repair process takes 24–30 hours. Three aspects of cell repair suggest that intercellular communication occurs across the dead cell; these are a precocious division of the cell below the dead cell, a reversible change in the morphology and growth of the shoot cell which participates in repair, and a definite attraction between the two cells which fuse. Thus during cell repair we find evidence not only for cellular redifferentiation through cell fusion, but also for extracellular substances which change pathways of morphogenesis.

紅藻ベニフクロノリとカタベニフクロノリ

The antheridium formation of Halosaccion saccatum Kütz. and Halosaccion firmum (Post. et Rupr.) Rupr. is reported in this paper. The materials used for the observations were collected from Akkeshi and Cape Erimo, the Pacific coast of Hokkaido, Japan during 1966-1967. The male plant of H. saccatum was found through all the seasons of the year, while that of H. firmum was collected from October to April.The developmental processes of the antheridium in both species are essentially similar each other, and these are also similar to that of Rhodymenia palmata (L.) Grev. reported by previous workers.The antheridium originates from the epidermal cell. In H. saccatum, the epidermal cell elongates and cuts off three to four cells from the upper corners obliquely, and these cells cut off again two antheridial mother cells each. In H. firmum, however, the epidermal cell cuts off directly two antheridial mother cells from the upper corners obliquely. In both the species, the antheridial mother cells protrude two primary antheridia each. The secondary antheridia protruded within the empty sheath of primary ones are usually seen, while the tertiary antheridia are rarely distinguished. There are some differences between these species in size and shape of the antheridial mother cells, antheridia and spermatia.

THE PHYLOGENY OF MONOCOTYLEDONS*

SummaryA large number of positive correlations exist among the following characters, which have been shown to be primitive for the Monocotyledons: Perianth present Perianth segments more than 5 Perianth homoiochlamydeous Perianth actinomorphic Perianth free Hermaphrodite Stamens 6 or more Carpels 3 or more Ovary inferior Ovules many Endosperm helobial or cellular Ripe pollen binucleate Ovules anatropous Parietal cell cut off from archesporial cell Embryo‐sac monosporic Pollen development simultaneous Leaves linear (uncertain) The antitheses of these characters (perianth absent, segments fewer than 6, hetero‐chlamydeous, etc.) represent advanced conditions.Four lists of taxa were used: Engler's families, Hutchinson's families, Engler's subfamilies and Hutchinson's tribes. In general the more taxa in the list the greater the proportion of significant results. Although Hutchinson's families are fewer in number than Engler's sub‐families, they give more significant results, suggesting that Hutchinson's system is the more ‘natural’.The ‘advancement indices’of the taxa comprising the two systems are compared. Hutchinson's scheme is found to be much more uniform than Engler's regarding the range of advancement within orders and families, further indicating that Hutchinson's is more ‘natural’.The trends of evolution in the Monocotyledons show a number of similarities with those found by Sporne in the Dicotyledons. For some characters evolution in the Monocotyledons appears to have taken a course similar to the more recent of the two Dicotyledonous trends. It is suggested that this indicates the derivation of the Monocotyledons from the Dicotyledons.The taxa have been arranged according to their relative advancement (Tables 10–13). This is a contribution towards our understanding of the phylogeny of the Monocotyledons. The interconnections of the taxa, backwards through time, can however be elucidated only by increased knowledge of the fossil record.